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How is air pollution produced? What things are responsible for it?

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How is air pollution produced? What things are responsible for it?

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According to IQair, air pollution has cost about 3300 deaths, and also cost approximately $11,763,502,500 HKD in hong kong in just 2023. Over 50% of air pollution is responsible for cars. There are about 275 vehicles per km on Hong Kong's roads, which are known for having the highest vehicle density in the world. the two biggest producers of electricity in hong kong, HK Electric Holdings and CLP (China Light and Power), produce more than 75,000 tonnes of carbon dioxide (CO2).

air pollution on human health has been widely recognized. According to the World Health Organization, outdoor air pollution ranked 14 across the globe in terms of mortality risk in 2004

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People with balconies could try to plant more plants and to encourage them, the government can give them free seeds, preferably edible ones. Each house has at least one potted plant that has leaves, for photosynthesis.

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Place solar panels on the top of cars, you can still use gas on rainy days, try to use more electric cars. Solar panels are 30,000 HKD −50,000 HKD, which might be too expensive.

Apply some sustainable methods to public transport, because they are used very often

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https://www.iqair.com/hong-kong

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How bad is the air quality in Hong Kong?

The quality of air in Hong Kong is considered a serious matter. For over 30 per cent of the year, visibility is less than 8 kilometres. Haze is often seen hanging over the city which can last for several days, depending on the direction of the prevailing winds. Because of this reduction in air quality, cases of bronchial infections and asthma has risen sharply. The average air quality index for 2019 was 96 US AQI with a PM2.5 of 33.5 µg/m³ together with significant amounts of PM10, O ₃, NO ₂, SO ₂ and CO, according to data published on the IQAir website. The World Health Organisation (WHO) recommend PM2.5 levels to be no higher than 10 µg/m3. The quality of air is monitored by 11 stations and 3 roadside ones. Readings are taken on an hourly basis to measure the suspended fine particulate matter which is proven to be most hazardous to health.

Ground-level ozone (O ₃) is formed when VOCs (Volatile Organic Compounds) and oxides of nitrogen (NO x) react with ultraviolet light. The main source of these pollutants comes from vehicle emissions of which there is plenty throughout the city. Ground-level ozone is at its height during the afternoon when the sun's rays are the strongest and even more so during the summer months. It is reported that the ozone level has increased by 21 per cent when compared to figures from 2019. Annual figures released by the monitoring network show ozone concentrations of 58 µg/m³ which is the same as it was in 2017 but the worst recorded since 2011. Data is collected from 23 monitors situated in Hong Kong, Macau and Guangdong as part of a joint initiative to significantly improve the quality of air within the region.

On 3rd September 2020, air pollution was recorded as being at the "serious" level in parts of Hong Kong. This is partly due to the hottest summer ever recorded since records began in 1884

Why is Hong Kong air quality so bad?

Over 50 per cent of the polluted air in Hong Kong comes from local sources. Vehicles on the city's streets with their idling engines and the fumes emitted by marine vessels. There are an estimated 275 vehicles per kilometre congesting the roads in Hong Kong which are known as having the highest density of vehicles anywhere in the world. Another contributing factor is the emissions from the coal-fired power stations. External factors also come into play with the substantial amount of polluted air which drifts down from neighbouring China. Emissions from the heart of China's manufacturing industries in the Pearl River Delta caused by thousands of factories are carried by the prevailing winds in the direction of Hong Kong. Two other major contributors are the two largest producers of electricity, namely H K Electric holdings and China Light and Power, between them they emit more than 75,000 tonnes of Carbon Dioxide (CO ₂) into the atmosphere.

PM2.5 particulate matter is a complex mixture of many dangerous pollutants such as black carbon (BC), smoke, nitrates, dust, sulphates and even rubber. These microscopic particles bypass the body's defence mechanism and become deeply lodged in the alveoli at the base of the bronchial tubes. Because of their size, they can easily pass through body tissue and eventually enter the heart. Once inside the heart they can lead to irregular heartbeats, nonfatal heart attacks and premature death of those suffering from pre-existing conditions.

Most of the sulphur dioxide (SO ₂) comes from vehicle emissions and the burning of fossil fuels. As well as aggravating health problems it also mixes with air and rain to produce sulphuric acid or acid rain. This can be damaging to all buildings and statues that it falls on as well as having a bad effect on any plants or trees. Crops suffer due to the effects of acid rain.

Even young healthy adults can be affected by poor quality air. The eyes, nose and throat can become irritated which then leads to coughing, tightness of the chest and often shortness of breath.

Figures have been taken from 3 roadside monitoring station and a pattern has been found that reveals very high concentrations of traffic-derived pollutants, namely nitrogen dioxide (NO ₂). The patterns follow both daily and weekly cycles. Seasonal changes are also noted duethe direction of the prevailing winds.

Container ships are the largest source of air pollution in and around Hong Kong. They produce most of the sulphur dioxide (SO ₂) nitrous oxides and PM2.5 particulates that are released daily into the environment.

How can Hong Kong improve the quality of its air?

The Environmental Protection Department (EDP) was established to help find a solution to the poor air quality and to assist in the provision of long-term acceptable levels of clean air.

A charitable organisation known as "Clean the Air "has been established with a goal of improving the air quality in Hong Kong. Voluntary phasing out of older diesel-fuelled vehicles has not been successful and further steps are needed to make this happen through new rules and regulations. Out of the 80,000 government operated diesel vehicles, 76,000 have already been taken out of service and the remaining 4,000 are expected to be retired within the next year. The emissions of PM2.5 particulates from power stations need to be reduced. Within the coming year, it is hoped that the coal-fired power stations will convert to the use of natural gas. The use of energy in both public and private buildings needs to be addressed with energy saving and efficient use of power. When cars are stopped at junctions, it is now required that the engines are turned off and not left idling. An idling engine produces large amounts of pollutant which discharge into the immediate area. This mandate was introduced in late 2007 which gave the patrols the power to impose a fixed penalty of HK$320 for the violation of the idling rule. It is now illegal for any driver to get out of their vehicle whilst the engines is still running. The law now prohibits the loitering of taxis and minibuses and they are not encouraged to loiter whilst waiting for clients. Mobile monitoring stations near busy junctions record this huge increase in pollution. Engine Idling Patrols have been established to remind motorists to switch their engines off whilst waiting. Marine vehicles are not exempt from scrutiny either, but more still needs to be done to establish a Clean Port Policy scheme. However, all vessels must use compliant fuel whilst docked. The local government has been asked to license all tobacco retailers and to increase the tax by way of discouraging people to smoke. Their aim is to educate the public in the fact that smoking costs the Hong Kong economy in excess of $70 billion per annum.

The promotion and use of electric vehicles would greatly increase the quality of air in Hong Kong. Already, the electrification of public transport is being encouraged and charging stations available for public use are being installed in strategic places around the city.

There is an app downloadable to mobile phones (PRAISE-HK) which aims to inform the user as to the quality of air in their immediate vicinity. This information will allow then to make a choice as to whether to venture outdoors or not. This app also predicts the quality of air for the next 48 hours by using data modelling and weather forecasts. It only uses data that has been verified by government officials and not merely extracted from sensors.

What are the effects on health due to poor air quality in Hong Kong?

As a result of comprehensive studies in The Netherlands, it has been noted that mortality rates are notably higher near heavily used roads. The comparison was made between residential properties 50 metres and 100 metres away from the main road. This is of great significance to residents of Hong Kong as the majority live within close proximity of major highways. It has been stated that air pollution exacerbates asthma, raises the risks of cardio-respiratory deaths and greatly impairs the function of the lungs. These risks are increased by2 to 3 per cent for every rise of 10 µg/m³ of pollutants. These roadside levels of pollution in Hong Kong are blamed for the 90,000 admissions to hospitals and the premature deaths of almost 3,000 people.

Even healthy people experience health impacts due to breathing in polluted air. Simple activities such as outdoor activities and exercise are greatly affected. It is recommended that good quality masks are worn when outside, and if living in close proximity to a road, it may be worth considering the installation of an air purifier in the home. High levels of air pollution can cause such problems as aggravated cardiovascular and respiratory illnesses. The heart and lungs become increasingly stressed as they need to work so much harder to keep an adequate supply of oxygen to the blood. Cells in the respiratory system easily become permanently damaged through breathing in these micro fine pollutants.

Over a longer period of time of exposure, the lungs prematurely age and thus lose capacity and suffer from a decrease in function. Diseases such as emphysema, asthma, bronchitis and even lung cancer are capable of developing under such circumstances. This, in turn, can lead to a shorter life-span.

Those most susceptible to severe health problems are those with existing problems which could include congestive heart failure or coronary artery disease. Pregnant women, the elderly and outdoor workers are particularly vulnerable as are children under 14 years and those who engage in vigorous outdoor exercise.

It has been estimated that 8,500 people have already lost their lives in 2020 due to air pollution. It has also been responsible for an estimated 6.8 million home visits from the doctor and 64,000 hospital-days.

On days when the air quality is classed as moderate (51-100 US AQI) residents are encouraged to make use of indoor facilities, where possible. Even taking a walk through a large shopping mall as part of your exercise regime is encouraged.

Does Hong Kong's poor air quality affect its economy?

As early as 2000 the recorded negative impact to the economy was in excess of HK$11.1 billion. It is estimated that 1,600 deaths can be avoided if the quality of the air in Hong Kong is improved. Having been made aware of these statistics it is said that pollution is driving away business and is detrimental to Hong Kong's global competitiveness. Amongst other things, it is being called a business issue and a political issue.

One large American investment and wealth management company have downgraded Hong Kong property companies because they are concerned about the quality of the air. The head of the Hong Kong Stock Exchange has been warned by several large foreign investment companies that local air pollution is scaring investors away. Because of the long periods of poor air quality and the threat that poses to health, many investors are looking at alternatives, such as Singapore.

It has been proven that the air pollution is not only harmful to the health of its citizens but it is a major factor when foreign workers think about relocating to Hong Kong. The Danish Chamber of Commerce in Hong Kong stated that several of its potential new employees have declined an offer of work in the city because of the health risks associated with working in such a polluted environment. Several years ago, new recruits did not consider Hong Kong to be an unhealthy city, on the contrary, it was thought of as a modern metropolis with clean air. However, it has been recommended by a London-based HR company that in order to attract new employees from abroad, local companies should offer a further 10 per cent salary increase by way of a "hardship" allowance because of the poor air quality. It has also been noted that almost one fifth of the population has at some time considered leaving the city, citing poor air quality as the main reason.

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Hong Kong SAR Air Quality Index (AQI) and Hong Kong SAR Air Pollution | IQAir

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The quality of air in Hong Kong is considered a serious matter. For over 30 per cent of the year, visibility is less than 8 kilometres. Haze is often seen hanging over the city which can last for several days, depending on the direction of the prevailing winds.

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地球之友 Friends of the Earth. (2023). Foe.org.hk. https://www.foe.org.hk/‌

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地球之友 Friends of the Earth. (2023). Foe.org.hk. https://www.foe.org.hk/‌

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We need a solution because, in 2000, the negative impact on the economy was about $11 billion HKD. it is approximated that 1600 deaths could be avoided if we improve air pollution in hong kong. Around 8,500 people in hong kong lost their lives in 2020 because of air pollution.

high levels of air pollution, increase the chance of cardiovascular and respiratory illnesses. As blood and oxygen levels decrease, the heart and lungs become more stressed. Cells in the respiratory system easily become damaged permanently through breathing in pollutants.

these leads to diseases such as emphysema, asthma, bronchitis, which can also decrease your lifespan.

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Our Work - Clean Air Network. (2023, May 13). Clean Air Network. https://hongkongcan.org/our-work/‌

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Our Work - Clean Air Network. (2023, May 13). Clean Air Network. https://hongkongcan.org/our-work/‌

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Planting more trees can really help with the air quality, and a solution is to plant some plants on buildings, because there isn't much space anywhere else. K11 is an excellent example, because they have the exterior of the mall covered in greenary.

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A rule that was established in Paris was that if the distance between you and your destination is under 15 minutes, you should walk or use vehicles that do not produce gas, such as bikes, or even walking, instead of driving to get there.

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In Seoul, Korea, diesel cars are banned, as diesel cars produce large amounts of green house gas

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During the Pandemic COVID-19, the French city officials recorded a large drop of nitrogen dioxide - a particle emitted by vehicles.To solidify these improvements, the mayor, Anne Hidalgo, wants to transform Paris into “a walkable city”, where the needs of residents can be met within a 15-minute stroll.

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Living, E. (2017, August 21). Environmental groups in Hong Kong: How you can help. Expat Living Hong Kong. https://expatliving.hk/environmental-groups-hong-kong/‌

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Living, E. (2017, August 21). Environmental groups in Hong Kong: How you can help. Expat Living Hong Kong. https://expatliving.hk/environmental-groups-hong-kong/‌

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Ark Eden Foundation helps the environment by holding eco-education in Lantau Island about pollution and what they can do themselves to keep HK more sustainable. They are a charity that have many restoration centres to help keep the environment/air as clean as possible.

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Friends of the Earth helps the environment by creating public policies and rules to keep the environment sustainable and also creating new business practices and community lifestyles that will support sustainability in environment.

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WWF is a company that helps keep track of HK's natural environment. They use this information to find scientific solutions to improve the environment or make it more sustainable.

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Clean Air Network helps keep good air quality by gaining support and help from public. In Nov 2022, Clean Air Network launched a project called "ON AIR", which is a public project on getting the public involved in helping the environment and take notice of air pollution.

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- Clean Air Network
- WWF Hong Kong
- Friends of the Earth
- Ark Eden Foundation

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Air pollution in Hong Kong is considered a serious problem. Visibility is less than eight kilometres for 30 per cent of the year. Cases of asthma and bronchial infections have soared in recent years due to reduced air quality.

Declining regional air quality means visibility has also decreased dramatically. In 2004, low visibility occurred 18 per cent of the time, the highest on record, according to the Hong Kong Observatory. Hong Kong is approaching the record of being the darkest city in the world with the least amount of sunlight hours, just after Edinburgh, Scotland.[citation needed ]

The mortality rate from vehicular pollution can be twice as high near heavily travelled roads, based on a study conducted in the Netherlands at residences 50 metres from a main road and 100 metres from a freeway. Since millions of people in Hong Kong live and work in close proximity to busy roads, this presents a major health risk to city residents. The Hong Kong Medical Association estimates that air pollution can exacerbate asthma, impair lung function and raise the risk of cardio-respiratory death by 2 to 3 per cent for every increase of 10 micrograms per cubic metre of pollutants. Studies by local public health experts have found that these roadside pollution levels are responsible for 90,000 hospital admissions and 2,800 premature deaths every year. In 2009 the Australian government highlighted that air pollution in Hong Kong could exacerbate some medical conditions.

Former Chief Executive Donald Tsang declared that the high life-expectancy of Hong Kong demonstrates that concerns over air quality were not justified.

The life expectancy in Hong Kong is among the highest in the world ... you can come to only one conclusion: we have the most environmental-friendly place for people, for executives, for Hong Kong people to live.

Professor Anthony Hedley, chair of community medicine at Hong Kong University, said: "Tsang is badly advised on current public health issues." Hedley added that air pollution levels in Hong Kong were extremely high, and could affect the lungs, blood vessels and heart. James Tien, former Chairman of the Liberal Party of Hong Kong, retorted, "Can [Tsang] really be confident that, if pollution continues to worsen, will he be able to promise the same life expectancy for our children and for our grandchildren?"

Even as early as 2000, the total negative impact to the Hong Kong Economy, including cardiorespiratory disease was in excess of HK$11.1 billion. About 1,600 deaths a year might be avoided if air quality improves.

Made aware of fresh statistical and anecdotal evidence that pollution is driving away business and hurting Hong Kong's global competitiveness, James Tien called air pollution "a health issue, a lifestyle issue, a tourism issue, a business issue, and increasingly a political issue."

Merrill Lynch downgraded several Hong Kong property companies because of air quality concerns, and there have been warnings from the head of the Stock Exchange that pollution was scaring investors away. It said that the air quality in Hong Kong is now regularly so poor that its "long-term competitiveness is in some doubt", and advised clients to switch into developers in Singapore instead.

Pollution is dramatically harming not only the health of citizens of Hong Kong but also its economy, particularly relating to the ability to attract skilled foreign labour.

The chairman of the Danish Chamber of Commerce in Hong Kong said each year at least two or three people decline offers to work in the Hong Kong offices of member companies because of pollution: "It's going to cost us in the future if we don't clean up here".

"Five years ago, air quality wasn't a concern when people considered whether to relocate to Hong Kong", said Jardine Engineering Corp. Chief Executive James Graham. "In the past, one of the advantages was clean air. We can no longer say that". A London-based human resources consultant recommends that companies pay a 10 per cent hardship allowance to lure expatriates, partly because of air quality.

As per the Clean Air Network, 53% of Hong Kong's pollution comes from local sources - power stations, idling engines of cars, trucks and buses and marine emissions. Hong Kong has only 5% of the land of the Pearl River Delta, but it creates 20% of its pollution, far more than its neighbouring cities of Shenzhen and Guangzhou.

A large portion of this pollution comes from coal-fired power stations in Hong Kong and vehicular traffic. A significant contribution wafts down from the tens of thousands of factories in China's neighboring manufacturing heartland of the Pearl River Delta. The two major electricity companies of Hong Kong, namely China Light and Power and HK Electric Holdings emit more than 75,000 tonnes of carbon dioxide into Hong Kong's air daily. At 275 vehicles per kilometer, Hong Kong also has among the highest density of vehicles in the world.

The Environmental Protection Department (EPD) in Hong Kong was established to solve problems and provide for a long lasting acceptable level of air quality.

In June 1995, instead of adopting internationally accepted benchmark index for pollution[vague ], it set up the Air Pollution Index as an indicator to pollution levels, both "General" and "Roadside".

Air Quality Objectives (AQOs) for seven widespread air pollutants were established in 1987 under the Air Pollution Control Ordinance (APCO), and have not been reviewed since it was set up. It is not clear how the levels are determined.

In October 2005, Task Force on Air Pollution criticised the Government for deluding itself with a pollution index that is a "meaningless" indicator of health risks. Professor Wong Tze-wai, at the Chinese University of Hong Kong commented that the current air pollution index "gives a false sense of security". Gary Wong, a professor at the Chinese University of Hong Kong's Department of Paediatrics and School of Public Health, said that under the current index, "some harmful pollution components aren't even recorded." In addition, he pointed out that there is no strategic plan or a timetable to tackle the problem, unlike in other countries

Street-level air quality regularly falls short of the government's Air Quality Objectives (AQOs), and even further short of the World Health Organization (WHO) Air Quality Guidelines, revised in October.

Academics called for Hong Kong Government to immediately update its air quality objectives set almost twenty years ago. For example, on 19 and 20 November 2006, roadside levels of respirable suspended particulates (RSPs - equivalent to PM ₁₀) exceeded the WHO guidelines by at least 300 per cent. Prof Anthony Hedley of the University of Hong Kong said in September 2007 that if Hong Kong's Air Pollution Index was based on WHO recommended levels, our readings would be "absolutely sky high" for most of the year. Secretary for Environment, Transport and Works Sarah Liao Sau-tung said the WHO targets were too stringent.

Air quality monitoring by the Department are carried out by 11 general stations and three roadside stations. On 8 March 2012, the Department started reporting data on fine suspended particulates in the air on an hourly basis, that are a leading component of smog. It began regular monitoring of PM 2.5 levels, which measure particles 2.5 micrometres (µm) in diameter or less, at three stations since 2005, but the data were never publicized.

In September 2008, Greenpeace East Asia's Hong Kong office launched its "Real Air Pollution Index" as part of a campaign to get the government to update the Air Pollution Index to match WHO guidelines. The Real Air Pollution Index reports hourly pollution levels from 15 monitoring stations across the region and compares them to WHO standards.

All HK taxis and PLBs now run on LPG.

In 2014, an ex gratia payment scheme was introduced to encourage vehicle-owners to scrap about 82,000 pre-Euro VI vehicles. This included a Citybus AEC Routemaster, which attracted controversy for its resulting loss of transport heritage.

Clear the Air is a charity organisation committed to improving air quality in Hong Kong. Current projects include:

Diesel - Recent government policies centred on voluntary schemes to phase out old polluting diesel vehicles (pre Euro 3) have proven ineffective. Further campaigns have to mandate a compulsory and scheduled phasing out of old polluting vehicles.

Energy - Aim to reduce harmful pollutants (PM2.5) from power station emissions through more stringent Air Quality Objectives (AQO). Work to improve energy savings and efficiency in all public and private buildings across Hong Kong.

Events & Education - Participating in and/or driving various territory wide environmental events and educational programs on clean air.

Idling Engines - Successful idling engine patrols have highlighted awareness among the public and the government of increased road side pollution leading to a ban on idling engines across Hong Kong to be tabled at Legco.

Indoor Air Quality (IAQ) - Free IAQ assessments for schools to be extended; the first campaign started April 2008.

Marine - Research conducted to implement a "smoky vessel spotter" scheme. More needs to be done to establish a Clean Port Policy scheme.

Tobacco - Clear The Air is advocating the Government to license all tobacco retailers, pressing the Financial Secretary to increase tobacco tax, pressing Legco to rescind the flawed qualified establishment exemptions and educating the public that the true cost of smoking to Hong Kong society is in excess of $73.32 billion per year.

Town Planning - Clear The Air defends the benchmark of "canyon effect" and Electronic Road Pricing (ERP) to auto-regulate urban traffic density.

The Action Blue Sky Campaign was an environmental campaign organised by the Environmental Protection Department, and launched by Chief Executive Donald Tsang in July 2006. Its campaign slogan in Chinese was "全城投入　為藍天打氣" (" Let all of the city join in to fight for a blue sky"), while its campaign slogan in English is "Clean Air for a Cool Hong Kong!" The campaign hoped to win support from the public as well as the business community, including those businesses investing in the Pearl River Delta Region.

In November 2007, the government launched a public consultation on the proposal which would impose a fixed penalty of HK$320 on drivers who would violate a ban on idling, with taxi and minibus drivers likely to bear the brunt of the ban. The government said its action is due to the failure of motorists to heed many past campaigns switch off engines while waiting. Taxi and minibus drivers were opposed to the proposal.

It is illegal for any driver to leave their engine running if they get out of their vehicle. The courts have been awarding fines of HK$700. It is also illegal for taxis to loiter and minibuses to stop longer than necessary to pick up or put down passengers. It is also illegal to park anywhere except in a designated parking place. This means that the vast majority of drivers who idle their engines are already in violation of at least one existing traffic safety law.

However, traffic wardens are under strict policy guidelines not to give out any tickets unless there has already developed a "serious" obstruction of the roadway or there have been multiple complaints made by the public; this is the "Selective Traffic Enforcement Policy" (STEP).

Traffic safety policing of idling vehicles, therefore, falls to private organisations like "mini spotters" who act as volunteer traffic wardens, making statements to police that can be prosecuted without traffic wardens having to issue tickets directly to the transport trade.

2008-09 Budget measures

In the 2008-09 Budget, Financial Secretary John Tsang proposed a 100 per cent profit tax deduction for capital expenditure on environmentally friendly machinery and equipment in the first year of purchase, to encourage the business community to go green. He also suggested shortening the depreciation period of this equipment from the usual 25 years to 5 years. Neither proposal was actually passed.

In January 2014, Secretary for the Environment Edward Yau Tang-wah announced that the HK government would update its air quality objectives, put in place in 1990, bringing them closer to WHO guidelines. According to the proposals, which will be set through legislation but have yet to be approved, seven types of emissions will be monitored. Respirable and fine particulates will also be monitored, but less stringently due to their more pronounced health impact. Targets set for three of the seven environmental pollutants are to be based on the WHO's loosest interim targets. Sulphur dioxide, nitrogen dioxide, carbon monoxide and lead would be subject to monitoring. Monitoring of particulates smaller than 2.5 µm (PM 2.5) would be introduced under the proposals, but will be loosest of the three WHO interim targets. Yau asserted some local pollution had roots in mainland China, but did not mention any ongoing dialogue to address the issue with mainland authorities. Yau also did not address roadside pollution in Hong Kong. In total, 22 measures in all were suggested to contribute towards meeting the new objectives. Such measures would include phasing out heavily polluting vehicles, promoting hybrid or electric vehicles, and increasing the use of natural gas, but no actions have yet to be taken. Environmental impact assessments of projects such as the Hong Kong-Zhuhai-Macau bridge were conducted and approved under the old air-quality guidelines. Mike Kilburn from Civic Exchange and Professor Hedley of the University of Hong Kong expressed their disappointment, saying that it too little, and too long overdue. Kilburn said: " It is a move that we have been waiting years for years but we are extremely disappointed as the objectives are not strict enough to make any positive impact on air quality." Other environmental activists shared little hope in government efforts to reduce pollution and lamented the half-hearted implementation of measures, and the elusiveness of timetable for meeting the most stringent objectives.

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Air pollution in Hong Kong is considered a serious problem. Visibility is less than eight kilometres for 30 per cent of the year. Cases of asthma and bronchial infections have soared in recent years due to reduced air quality. Declining regional air quality means visibility has also decreased dramatically.

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National Institute of Environmental Health Sciences

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Introduction

Air pollution is a familiar environmental health hazard. We know what we're looking at when brown haze settles over a city, exhaust billows across a busy highway, or a plume rises from a smokestack. Some air pollution is not seen, but its pungent smell alerts you.

It is a major threat to global health and prosperity. Air pollution, in all forms, is responsible for more than 6.5 million deaths each year globally, a number that has increased over the past two decades.

What Is Air Pollution?

Air pollution is a mix of hazardous substances from both human-made and natural sources.

Vehicle emissions, fuel oils and natural gas to heat homes, by-products of manufacturing and power generation, particularly coal-fueled power plants, and fumes from chemical production are the primary sources of human-made air pollution.

Nature releases hazardous substances into the air, such as smoke from wildfires, which are often caused by people; ash and gases from volcanic eruptions; and gases, like methane, which are emitted from decomposing organic matter in soils.

Traffic-Related Air Pollution (TRAP), a mixture of gasses and particles, has most of the elements of human-made air pollution: ground-level ozone, various forms of carbon, nitrogen oxides, sulfur oxides, volatile organic compounds, polycyclic aromatic hydrocarbons, and fine particulate matter.

Ozone, an atmospheric gas, is often called smog when at ground level. It is created when pollutants emitted by cars, power plants, industrial boilers, refineries, and other sources chemically react in the presence of sunlight.

Noxious gases, which include carbon dioxide, carbon monoxide, nitrogen oxides (NOx), and sulfur oxides (SOx), are components of motor vehicle emissions and byproducts of industrial processes.

Particulate matter (PM) is composed of chemicals such as sulfates, nitrates, carbon, or mineral dusts. Vehicle and industrial emissions from fossil fuel combustion, cigarette smoke, and burning organic matter, such as wildfires, all contain PM.

A subset of PM, fine particulate matter (PM 2.5) is 30 times thinner than a human hair. It can be inhaled deeply into lung tissue and contribute to serious health problems. PM 2.5 accounts for most health effects due to air pollution in the U.S.

Volatile organic compounds (VOC) vaporize at or near room temperature-hence, the designation volatile. They are called organic because they contain carbon. VOCs are given off by paints, cleaning supplies, pesticides, some furnishings, and even craft materials like glue. Gasoline and natural gas are major sources of VOCs, which are released during combustion.

Polycyclic aromatic hydrocarbons (PAH) are organic compounds containing carbon and hydrogen. Of more than 100 PAHs known to be widespread in the environment, 15 are listed in the Report on Carcinogens. In addition to combustion, many industrial processes, such as iron, steel, and rubber product manufacturing, as well as power generation, also produce PAHs as a by-product. PAHs are also found in particulate matter.

Air Pollution and Climate Change

Air pollution and climate change affect each other through complex interactions in the atmosphere. Air pollution is intricately linked with climate change because both problems come largely from the same sources, such as emissions from burning fossil fuels. Both are threats to people's health and the environment worldwide. Read more: Health Impacts of Air Quality.

What Is NIEHS Doing?

Over its 50-plus year history, NIEHS has been a leader in air pollution research. The institute continues to fund and conduct research into how air pollution affects health and the population groups who are most affected.

How does air pollution affect our health?

When the National Ambient Air Quality Standards were established in 1970, air pollution was regarded primarily as a threat to respiratory health. In 1993, NIEHS researchers published the landmark Six Cities Study, which established an association between fine particulate matter and mortality.

Air pollution exposure is associated with oxidative stress and inflammation in human cells, which may lay a foundation for chronic diseases and cancer. In 2013, the International Agency for Research on Cancer of the World Health Organization (WHO) classified air pollution as a human carcinogen.

Mortality rates related to air pollution are a concern. Exposure to the air pollutant PM2.5 is associated with an increased risk of death.

A team of researchers, partially funded by NIEHS, found that deaths decreased after air pollution regulations were implemented and coal-powered plants were retired. The study data covered 21 years. More specifically, they found exposure to PM2.5 from coal was associated with a mortality risk that was twice as high as the risk from exposure to PM2.5 from all sources. PM2.5 from coal is high in sulfur dioxide, black carbon, and metals.

Public health concerns include cancer, cardiovascular disease, respiratory diseases, diabetes mellitus, obesity, and reproductive, neurological, and immune system disorders.

Research on air pollution and health effects continually advances.

Cancer

A large study of more than 57,000 women found living near major roadways may increase a woman's risk for breast cancer.

The NIEHS Sister Study found other airborne toxic substances, especially methylene chloride, which is used in aerosol products and paint removers, are also associated with increased risk of breast cancer.

Occupational exposure to benzene, an industrial chemical and component of gasoline, can cause leukemia and is associated with non-Hodgkin's Lymphoma.

A long-term study, 2000-2016, found an association between lung cancer incidence and increased reliance on coal for energy generation.

Cardiovascular Disease

Fine particulate matter can impair blood vessel function and speed up calcification in arteries.

NIEHS researchers established links between short-term daily exposure by post-menopausal women to nitrogen oxides and increased risk of hemorrhagic stroke.

For some older Americans, exposure to TRAP can result in lowered levels of high-density lipoprotein, sometimes called good cholesterol, increasing their risk for cardiovascular disease.

According to a National Toxicology Program (NTP) , TRAP exposure also increases a pregnant woman's risk for dangerous changes in blood pressure, known as hypertensive disorders, which are a leading cause of pre-term birth, low birth weight, and maternal and fetal illness and death.

Respiratory Disease

Air pollution can affect lung development and is implicated in the development of , asthma, and other respiratory diseases, such as chronic obstructive pulmonary disease (COPD).

Increases in asthma prevalence and severity are linked to urbanization and outdoor air pollution. Children living in low-income urban areas tend to have more asthma cases than others. Research published in 2023 tied two air pollutants, ozone and PM2.5, to asthma-related changes in children's airways.

PM and nitrogen oxide are linked to chronic bronchitis.

In 2020, a major public health challenge was confluence of the COVID-19 pandemic and wildfires across the western U.S. Building on a well-established connection between air pollution and respiratory-tract infections, a study linked wildfire smoke with additional COVID-19 cases and deaths.

Whom does air pollution affect the most?

Air pollution affects everyone's health, but certain groups may be harmed more.
Almost 9 out of 10 people who live in urban areas worldwide are affected by air pollution.
Children
The NIEHS-funded Children's Health Study at the University of Southern California is one of the largest studies of the long-term effects of air pollution on children's respiratory health. Among its findings:

Higher air pollution levels increase short-term respiratory infections, which lead to more school absences.

Children who play several outdoor sports and live in high ozone communities are more likely to develop asthma.

Children living near busy roads are at increased risk for asthma.

Children with asthma who were exposed to high levels of air pollutants were more likely to develop bronchitis symptoms.

Living in communities with higher pollution levels can cause lung damage.

Other studies on women and children

NIEHS-funded researchers from the University of California, Davis, Environmental Health Sciences Center are conducting the Bio-Specimen and Fire Effects (B-SAFE) Study. This ongoing project seeks to discover if and how recent wildfires and their smoke affected pregnant women and their babies. Begun in 2017, study participants are pregnant women who were living in Northern California when the 2018, 2019, or 2020 wildfires occurred there.

Breathing PM 2.5, even at relatively low levels, may alter the size of a child's developing brain, which may ultimately increase the risk for cognitive and emotional problems later in adolescence.

Prenatal exposure to PAHs was associated with brain development effects, slower processing speed, attention-deficit and hyperactivity disorder (ADHD) symptoms, and other neurobehavioral problems in urban youth.

In New York City, prenatal exposure to air pollution may play a role in childhood ADHD-related behavior problems.

Prenatal exposure to particulate matter was associated with low birth weight.

Women exposed to high levels of fine particulate matter during pregnancy, particularly in the third trimester, may have up to twice the risk of having a child with autism.

Second and third trimester exposure to PM 2.5 might increase the chance of those children having high blood pressure in early life.

In California's agricultural San Joaquin Valley, women who were exposed to high levels of carbon monoxide, nitrogen oxide, or nitrogen dioxide during their first 8 weeks of pregnancy were more likely to have a baby with neural tube defects.

In Marietta, Ohio, home to a ferromanganese refinery, manganese concentrations in blood and hair, a biomarker of air pollution exposure, were associated with lower child IQ scores.

Older adults

Alzheimer's disease and related dementias are a public health challenge for aging populations. NIEHS-funded researchers at the University of Washington identified a link between air pollution and dementias. This well-conducted study adds considerable evidence that ambient air fine particles increase risk of dementias. Conversely, a multi-year study published in 2022 shows improved air quality is associated with lower risk of dementia in older women. The researchers also stated this decline in dementia risk was equivalent to taking nearly 2 1/2 years off the age of the women studied.

Air pollution was linked to a greater chance of developing several neurological disorders, including Parkinson's disease, Alzheimer's disease, and other dementias. Hospital admissions data from 63 million older adults in the U.S., obtained over 17 years (2000-2016), was analyzed along with estimated PM 2.5 concentrations by zip code to conduct the study.

In older adults, long-term exposure to TRAP may significantly hasten physical disabilities. The risk is more pronounced among racial minorities and lower-income people.

Osteoporosis affects women more than men. A large study associated high levels of air pollutants with bone damage, particularly in the lumbar spine, among postmenopausal women. This study expands previous findings linking air pollution and bone damage.

Nutrients may counter some harmful effects from air pollution. A 2020 study found omega-3 fatty acids, obtained by eating certain fish, may protect against PM 2.5-associated brain shrinkage in older women.

Rural dwellers

An NIEHS-funded study found that concentrations of PM 2.5 in rural Washington State were comparable to urban Seattle. In this study, as regional PM 2.5 increased, there were increased asthma symptoms, such as limitation of activities, more wheezing, and more nighttime waking, in rural children.

NIEHS supported a translational research project, Addressing Air Pollution and Asthma (1MB) , that may lead to improved health for children suffering from asthma. They found that certain agricultural practices contribute to poor air quality and asthma among children. The team combined high-efficiency particulate air (HEPA) cleaners and a home-based education program to reduce children's exposure to pollutants in the home.

In the rural U.S., large-scale animal feeding operations might compromise regional air quality through emission of pollutants, such as ammonia gas. A study found acute lung function problems in children with asthma in such areas.

Different genes
Your genes play a role in respiratory health. NIEHS-funded research discovered that people with specific gene variants, which made them more likely to have lung inflammation, had a greater chance of suffering from asthma if they lived close to major roadways.

NIEHS and community involvement

NIEHS supports community participation in the research process and encourages collaborative approaches that build capacity in communities to address environmental health concerns. Community-engaged research and citizen science are two types of collaborative research approaches.

For example, NIEHS helps residents of Imperial County, California track air pollution through a network of 40 community-run monitors. In this county, long-term improvements in air quality were associated with significant lung-function improvement in children.

In another example, NIEHS grant recipients developed community-level tactics and public policies for reducing exposure to TRAP:

Using high-efficiency particulate air (HEPA) filtration.

Building land-use buffers and vegetation barriers.

Improving urban design with gardens, parks, and street-side trees.

Creating active-travel options, such as bicycling and walking paths.

THE (Trade, Health, Environment) Impact Project brings together researchers and community groups to find solutions for communities affected by trade-related pollution, such as ports and roadways with trucking.

Join an asthma study!

The goal of the Natural History of Asthma with Longitudinal Environmental Sampling (NHALES) study is to help scientists understand how bacteria and other factors in the environment affect people who have moderate to severe asthma.

Who can participate?

Moderate to severe asthmatics.

Males and females, aged 18-60.

Females should not be pregnant or breastfeeding at the start of the study, but may still participate if they become pregnant during the study.

Nonsmokers who are also not around significant amounts of secondhand smoke.

No history of chronic obstructive pulmonary disease, emphysema, cystic fibrosis (CF), pulmonary fibrosis, non-CF bronchiectasis, sarcoidosis, unstable angina, or pulmonary hypertension.

Not allergic to methacholine.

Able to provide your own transportation to clinic visits on the NIEHS campus in North Carolina.

For more information about this study:

NHALES: Asthma Study

Tel 855-MYNIEHS (855-696-4347)
nhales@mail.nih.gov

Why improving air quality matters

Air pollution and birth outcomes are linked as global public health concerns. Researchers analyzed indoor and outdoor air pollution data from all inhabited continents along with key pregnancy outcomes. Their findings indicate efforts to reduce PM2.5 exposure could lead to significant reductions in the number of low-birth weight and pre-term birth infants worldwide. Air pollution reduction would be especially beneficial for children born in low- and middle-income countries.

Among children in Southern California, decreases in ambient nitrogen dioxide and PM 2.5 were associated with fewer cases of asthma.

An NIEHS-funded study found that a mixture of several B vitamins may protect DNA from changes attributable to PM 2.5 air pollution.

Bronchitis symptoms declined as pollution levels dropped in the Los Angeles region.

Improving air quality may improve cognitive function and reduce dementia risk, according to supported in part by NIH and the Alzheimer's Association.

When fossil-fuel power plants close, nearby air pollution is reduced. A study found the incidence of preterm births went down within 5 kilometers of retired coal and oil-powered plant locations.

Further Reading

Stories from the Environmental Factor (NIEHS newsletter)

Printable Fact Sheets

Podcasts

Additional Resources

Air Pollution Linked to Dementia Cases (September 2023) - In this edition of NIH Research Matters, read about findings from the Health and Retirement Study, funded by the National Institute on Aging, that showed higher air pollution exposure was linked to an increased risk of dementia. After consideration of all sources, fine particulate matter, or PM2.5, from agriculture and wildfires were specifically associated with an increased risk of dementia. Reducing such exposures might help lower the incidence of dementia. The study was published in JAMA Internal Medicine.

, a tool developed in partnership by several government agencies, allows you to monitor air quality in real time anywhere in the U.S. Simply enter your zip code as indicated on the website.

EPA's Air Sensor Toolbox provides information on the operation and use of air-sensor monitoring systems for technology developers, air-quality managers, citizen scientists, and the public.

NIH Climate Change and Health Initiative - This solutions-focused research initiative aims to reduce the health consequences associated with extreme weather events and evolving climate conditions. NIH has a strong history of creating innovative tools, technologies, and data-driven solutions to address global environmental problems.

Smoke-ready Toolbox for Wildfires is a compendium of resources from the EPA to help educate you about the risks of smoke exposure and actions that protect your health.

Wildfire Smoke Collection - The journal Environmental Health Perspectives has published high-impact papers and reviews exploring exposure and resulting health effects related to wildfires.

Related Health Topics

This content is available to use on your website.

Please visit NIEHS Syndication to get started.

Introduction

Air pollution is a familiar environmental health hazard. We know what we're looking at when brown haze settles over a city, exhaust billows across a busy highway, or a plume rises from a smokestack. Some air pollution is not seen, but its pungent smell alerts you.

It is a major threat to global health and prosperity. Air pollution, in all forms, is responsible for more than 6.5 million deaths each year globally, a number that has increased over the past two decades.

What Is Air Pollution?

Air pollution is a mix of hazardous substances from both human-made and natural sources.

Vehicle emissions, fuel oils and natural gas to heat homes, by-products of manufacturing and power generation, particularly coal-fueled power plants, and fumes from chemical production are the primary sources of human-made air pollution.

Nature releases hazardous substances into the air, such as smoke from wildfires, which are often caused by people; ash and gases from volcanic eruptions; and gases, like methane, which are emitted from decomposing organic matter in soils.

Traffic-Related Air Pollution (TRAP), a mixture of gasses and particles, has most of the elements of human-made air pollution: ground-level ozone, various forms of carbon, nitrogen oxides, sulfur oxides, volatile organic compounds, polycyclic aromatic hydrocarbons, and fine particulate matter.

Ozone, an atmospheric gas, is often called smog when at ground level. It is created when pollutants emitted by cars, power plants, industrial boilers, refineries, and other sources chemically react in the presence of sunlight.

Noxious gases, which include carbon dioxide, carbon monoxide, nitrogen oxides (NOx), and sulfur oxides (SOx), are components of motor vehicle emissions and byproducts of industrial processes.

Particulate matter (PM) is composed of chemicals such as sulfates, nitrates, carbon, or mineral dusts. Vehicle and industrial emissions from fossil fuel combustion, cigarette smoke, and burning organic matter, such as wildfires, all contain PM.

A subset of PM, fine particulate matter (PM 2.5) is 30 times thinner than a human hair. It can be inhaled deeply into lung tissue and contribute to serious health problems. PM 2.5 accounts for most health effects due to air pollution in the U.S.

Volatile organic compounds (VOC) vaporize at or near room temperature-hence, the designation volatile. They are called organic because they contain carbon. VOCs are given off by paints, cleaning supplies, pesticides, some furnishings, and even craft materials like glue. Gasoline and natural gas are major sources of VOCs, which are released during combustion.

Polycyclic aromatic hydrocarbons (PAH) are organic compounds containing carbon and hydrogen. Of more than 100 PAHs known to be widespread in the environment, 15 are listed in the Report on Carcinogens. In addition to combustion, many industrial processes, such as iron, steel, and rubber product manufacturing, as well as power generation, also produce PAHs as a by-product. PAHs are also found in particulate matter.

Air Pollution and Climate Change

Air pollution and climate change affect each other through complex interactions in the atmosphere. Air pollution is intricately linked with climate change because both problems come largely from the same sources, such as emissions from burning fossil fuels. Both are threats to people's health and the environment worldwide. Read more: Health Impacts of Air Quality.

What Is NIEHS Doing?

Over its 50-plus year history, NIEHS has been a leader in air pollution research. The institute continues to fund and conduct research into how air pollution affects health and the population groups who are most affected.

How does air pollution affect our health?

When the National Ambient Air Quality Standards were established in 1970, air pollution was regarded primarily as a threat to respiratory health. In 1993, NIEHS researchers published the landmark Six Cities Study, which established an association between fine particulate matter and mortality.

Air pollution exposure is associated with oxidative stress and inflammation in human cells, which may lay a foundation for chronic diseases and cancer. In 2013, the International Agency for Research on Cancer of the World Health Organization (WHO) classified air pollution as a human carcinogen.

Mortality rates related to air pollution are a concern. Exposure to the air pollutant PM2.5 is associated with an increased risk of death.

A team of researchers, partially funded by NIEHS, found that deaths decreased after air pollution regulations were implemented and coal-powered plants were retired. The study data covered 21 years. More specifically, they found exposure to PM2.5 from coal was associated with a mortality risk that was twice as high as the risk from exposure to PM2.5 from all sources. PM2.5 from coal is high in sulfur dioxide, black carbon, and metals.

Public health concerns include cancer, cardiovascular disease, respiratory diseases, diabetes mellitus, obesity, and reproductive, neurological, and immune system disorders.

Research on air pollution and health effects continually advances.

Cancer

A large study of more than 57,000 women found living near major roadways may increase a woman's risk for breast cancer.

The NIEHS Sister Study found other airborne toxic substances, especially methylene chloride, which is used in aerosol products and paint removers, are also associated with increased risk of breast cancer.

Occupational exposure to benzene, an industrial chemical and component of gasoline, can cause leukemia and is associated with non-Hodgkin's Lymphoma.

A long-term study, 2000-2016, found an association between lung cancer incidence and increased reliance on coal for energy generation.

Cardiovascular Disease

Fine particulate matter can impair blood vessel function and speed up calcification in arteries.

NIEHS researchers established links between short-term daily exposure by post-menopausal women to nitrogen oxides and increased risk of hemorrhagic stroke.

For some older Americans, exposure to TRAP can result in lowered levels of high-density lipoprotein, sometimes called good cholesterol, increasing their risk for cardiovascular disease.

According to a National Toxicology Program (NTP) , TRAP exposure also increases a pregnant woman's risk for dangerous changes in blood pressure, known as hypertensive disorders, which are a leading cause of pre-term birth, low birth weight, and maternal and fetal illness and death.

Respiratory Disease

Air pollution can affect lung development and is implicated in the development of , asthma, and other respiratory diseases, such as chronic obstructive pulmonary disease (COPD).

Increases in asthma prevalence and severity are linked to urbanization and outdoor air pollution. Children living in low-income urban areas tend to have more asthma cases than others. Research published in 2023 tied two air pollutants, ozone and PM2.5, to asthma-related changes in children's airways.

PM and nitrogen oxide are linked to chronic bronchitis.

In 2020, a major public health challenge was confluence of the COVID-19 pandemic and wildfires across the western U.S. Building on a well-established connection between air pollution and respiratory-tract infections, a study linked wildfire smoke with additional COVID-19 cases and deaths.

Whom does air pollution affect the most?

Air pollution affects everyone's health, but certain groups may be harmed more.
Almost 9 out of 10 people who live in urban areas worldwide are affected by air pollution.
Children
The NIEHS-funded Children's Health Study at the University of Southern California is one of the largest studies of the long-term effects of air pollution on children's respiratory health. Among its findings:

Higher air pollution levels increase short-term respiratory infections, which lead to more school absences.

Children who play several outdoor sports and live in high ozone communities are more likely to develop asthma.

Children living near busy roads are at increased risk for asthma.

Children with asthma who were exposed to high levels of air pollutants were more likely to develop bronchitis symptoms.

Living in communities with higher pollution levels can cause lung damage.

Other studies on women and children

NIEHS-funded researchers from the University of California, Davis, Environmental Health Sciences Center are conducting the Bio-Specimen and Fire Effects (B-SAFE) Study. This ongoing project seeks to discover if and how recent wildfires and their smoke affected pregnant women and their babies. Begun in 2017, study participants are pregnant women who were living in Northern California when the 2018, 2019, or 2020 wildfires occurred there.

Breathing PM 2.5, even at relatively low levels, may alter the size of a child's developing brain, which may ultimately increase the risk for cognitive and emotional problems later in adolescence.

Prenatal exposure to PAHs was associated with brain development effects, slower processing speed, attention-deficit and hyperactivity disorder (ADHD) symptoms, and other neurobehavioral problems in urban youth.

In New York City, prenatal exposure to air pollution may play a role in childhood ADHD-related behavior problems.

Prenatal exposure to particulate matter was associated with low birth weight.

Women exposed to high levels of fine particulate matter during pregnancy, particularly in the third trimester, may have up to twice the risk of having a child with autism.

Second and third trimester exposure to PM 2.5 might increase the chance of those children having high blood pressure in early life.

In California's agricultural San Joaquin Valley, women who were exposed to high levels of carbon monoxide, nitrogen oxide, or nitrogen dioxide during their first 8 weeks of pregnancy were more likely to have a baby with neural tube defects.

In Marietta, Ohio, home to a ferromanganese refinery, manganese concentrations in blood and hair, a biomarker of air pollution exposure, were associated with lower child IQ scores.

Older adults

Alzheimer's disease and related dementias are a public health challenge for aging populations. NIEHS-funded researchers at the University of Washington identified a link between air pollution and dementias. This well-conducted study adds considerable evidence that ambient air fine particles increase risk of dementias. Conversely, a multi-year study published in 2022 shows improved air quality is associated with lower risk of dementia in older women. The researchers also stated this decline in dementia risk was equivalent to taking nearly 2 1/2 years off the age of the women studied.

Air pollution was linked to a greater chance of developing several neurological disorders, including Parkinson's disease, Alzheimer's disease, and other dementias. Hospital admissions data from 63 million older adults in the U.S., obtained over 17 years (2000-2016), was analyzed along with estimated PM 2.5 concentrations by zip code to conduct the study.

In older adults, long-term exposure to TRAP may significantly hasten physical disabilities. The risk is more pronounced among racial minorities and lower-income people.

Osteoporosis affects women more than men. A large study associated high levels of air pollutants with bone damage, particularly in the lumbar spine, among postmenopausal women. This study expands previous findings linking air pollution and bone damage.

Nutrients may counter some harmful effects from air pollution. A 2020 study found omega-3 fatty acids, obtained by eating certain fish, may protect against PM 2.5-associated brain shrinkage in older women.

Rural dwellers

An NIEHS-funded study found that concentrations of PM 2.5 in rural Washington State were comparable to urban Seattle. In this study, as regional PM 2.5 increased, there were increased asthma symptoms, such as limitation of activities, more wheezing, and more nighttime waking, in rural children.

NIEHS supported a translational research project, Addressing Air Pollution and Asthma (1MB) , that may lead to improved health for children suffering from asthma. They found that certain agricultural practices contribute to poor air quality and asthma among children. The team combined high-efficiency particulate air (HEPA) cleaners and a home-based education program to reduce children's exposure to pollutants in the home.

In the rural U.S., large-scale animal feeding operations might compromise regional air quality through emission of pollutants, such as ammonia gas. A study found acute lung function problems in children with asthma in such areas.

Different genes
Your genes play a role in respiratory health. NIEHS-funded research discovered that people with specific gene variants, which made them more likely to have lung inflammation, had a greater chance of suffering from asthma if they lived close to major roadways.

NIEHS and community involvement

NIEHS supports community participation in the research process and encourages collaborative approaches that build capacity in communities to address environmental health concerns. Community-engaged research and citizen science are two types of collaborative research approaches.

For example, NIEHS helps residents of Imperial County, California track air pollution through a network of 40 community-run monitors. In this county, long-term improvements in air quality were associated with significant lung-function improvement in children.

In another example, NIEHS grant recipients developed community-level tactics and public policies for reducing exposure to TRAP:

Using high-efficiency particulate air (HEPA) filtration.

Building land-use buffers and vegetation barriers.

Improving urban design with gardens, parks, and street-side trees.

Creating active-travel options, such as bicycling and walking paths.

THE (Trade, Health, Environment) Impact Project brings together researchers and community groups to find solutions for communities affected by trade-related pollution, such as ports and roadways with trucking.

Join an asthma study!

The goal of the Natural History of Asthma with Longitudinal Environmental Sampling (NHALES) study is to help scientists understand how bacteria and other factors in the environment affect people who have moderate to severe asthma.

Who can participate?

Moderate to severe asthmatics.

Males and females, aged 18-60.

Females should not be pregnant or breastfeeding at the start of the study, but may still participate if they become pregnant during the study.

Nonsmokers who are also not around significant amounts of secondhand smoke.

No history of chronic obstructive pulmonary disease, emphysema, cystic fibrosis (CF), pulmonary fibrosis, non-CF bronchiectasis, sarcoidosis, unstable angina, or pulmonary hypertension.

Not allergic to methacholine.

Able to provide your own transportation to clinic visits on the NIEHS campus in North Carolina.

For more information about this study:

NHALES: Asthma Study

Tel 855-MYNIEHS (855-696-4347)
nhales@mail.nih.gov

Why improving air quality matters

Air pollution and birth outcomes are linked as global public health concerns. Researchers analyzed indoor and outdoor air pollution data from all inhabited continents along with key pregnancy outcomes. Their findings indicate efforts to reduce PM2.5 exposure could lead to significant reductions in the number of low-birth weight and pre-term birth infants worldwide. Air pollution reduction would be especially beneficial for children born in low- and middle-income countries.

Among children in Southern California, decreases in ambient nitrogen dioxide and PM 2.5 were associated with fewer cases of asthma.

An NIEHS-funded study found that a mixture of several B vitamins may protect DNA from changes attributable to PM 2.5 air pollution.

Bronchitis symptoms declined as pollution levels dropped in the Los Angeles region.

Improving air quality may improve cognitive function and reduce dementia risk, according to supported in part by NIH and the Alzheimer's Association.

When fossil-fuel power plants close, nearby air pollution is reduced. A study found the incidence of preterm births went down within 5 kilometers of retired coal and oil-powered plant locations.

Further Reading

Stories from the Environmental Factor (NIEHS newsletter)

Printable Fact Sheets

Podcasts

Additional Resources

Air Pollution Linked to Dementia Cases (September 2023) - In this edition of NIH Research Matters, read about findings from the Health and Retirement Study, funded by the National Institute on Aging, that showed higher air pollution exposure was linked to an increased risk of dementia. After consideration of all sources, fine particulate matter, or PM2.5, from agriculture and wildfires were specifically associated with an increased risk of dementia. Reducing such exposures might help lower the incidence of dementia. The study was published in JAMA Internal Medicine.

, a tool developed in partnership by several government agencies, allows you to monitor air quality in real time anywhere in the U.S. Simply enter your zip code as indicated on the website.

EPA's Air Sensor Toolbox provides information on the operation and use of air-sensor monitoring systems for technology developers, air-quality managers, citizen scientists, and the public.

NIH Climate Change and Health Initiative - This solutions-focused research initiative aims to reduce the health consequences associated with extreme weather events and evolving climate conditions. NIH has a strong history of creating innovative tools, technologies, and data-driven solutions to address global environmental problems.

Smoke-ready Toolbox for Wildfires is a compendium of resources from the EPA to help educate you about the risks of smoke exposure and actions that protect your health.

Wildfire Smoke Collection - The journal Environmental Health Perspectives has published high-impact papers and reviews exploring exposure and resulting health effects related to wildfires.

Related Health Topics

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Air pollution is a familiar environmental health hazard. We know what we're looking at when brown haze settles over a city, exhaust billows across a busy highway, or a plume rises from a smokestack. Some air pollution is not seen, but its pungent smell alerts you.

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Turning Hong Kong into a smart city has long been on the government's agenda. With smart mobility being the first hands-on experience for the public, experts told Wang Yuke that private cars are the first hurdle in this transformation.
We have come to the dying days of the private automobile, experts tell us, and Hong Kong is joining a global movement to stem the spread of what has become an urban nightmare.

Electronic road pricing (ERP) seems apt for a city experiencing excessive gas pedal and dyspepsia from a glut of urban traffic. It's a system Hong Kong plans to implement next year. Its objective is to levy fees against motorized vehicles which insist on driving on the city's most congested roads during peak commuting hours.

We can steer people from buying private vehicles by providing even better public transport
Evan Auyang , chairman of Civic Exchange

Introduction of ERP will reduce the reliance on private vehicles, says Charles So, chairman of Smart Mobility Committee of the Smart City Consortium. The feasibility of ERP has been under study since 1997. The Transport Department released its study of the proposal last year. The study recommended that charges be levied at peak traffic hours throughout the day, especially 8 am to 9 am and 5:30 pm to 7 pm. The study also recommended lower chargers during inter-peak hours and went on to predict that the reduced traffic would mean that travel times through the city's torrid zones could be cut by up to 25 percent.

Singapore was the first city to introduce ERP in 1998. Wireless technology has been adapted to link an overhead system registering the passing traffic with wireless units inside vehicles on the road. The traffic levy is deducted from a smart card inside the in-vehicle-unit.

So envisioned in-vehicle units factoring into the Hong Kong ERP. He noted that apart from ERP charging, the in-vehicle-unit system will collect traffic data for analysis.

An autonomous vehicle is under trial in the city. (PHOTO PROVIDED TO CHINA DAILY)

There are roughly 600,000 private cars in Hong Kong. That's not bad given the city's 2.51 million households. What is alarming, however, is that the number of private cars grew by 48.7 percent between 2006 and 2016. That's 3 to 4 percent a year. The population has grown only 0.4 percent annually over the past 15 years.

Private cars are huge contributors to the traffic problem in Hong Kong, said Evan Auyang, chairman of the independent public policy think tank Civic Exchange. He points out that the addition of traffic lanes cannot accommodate the excess traffic for the past 10 years. It's predicted that the annual growth rate of road length would slow down to around 0.4 percent - lower than the annual increase in the growth rate of private vehicles. The findings came from a study, released in 2014, by the Transport Advisory Committee.
What does it all mean?
The direct consequence of more and more private cars on the road is, "it takes longer to get there". The average speed of vehicles on the road dropped from 25.6 km/h in 2003 to 22.7 km/h in 2013.

Regular commuters are faced almost daily with the congestion nightmare. Take Grace Mak, manager of the famous high jumper Cecilia Yeung Man-wai. Mak likes to be on time but that can be a challenge in Hong Kong. "I was late by half an hour for a scheduled shooting session with Cecilia. I felt very sorry about that," recalled Mak. "The photo shoot was scheduled at around noon. I expected traffic would be heavy, so I left an hour and a half early. I ended up being trapped in a taxi in the Cross-Harbour Tunnel." Mak's frustration stems from the fact that celebrities are often on tight schedules. It's Mak's job to make sure they get to where they're going on time. She lamented the fact that traffic is getting worse but there're still no restrictions on the growing number of private cars.

"We can't stop people from buying cars, but we can steer people from buying private vehicles by providing even better public transport, by making private cars more expensive to buy via raising first registration tax, and making private cars more costly to use by enforcing congestion pricing," opined Auyang.

Future road users - pedestrians and vehicular users - and street furniture, such as signs, can communicate with each other. (PHOTO PROVIDED TO CHINA DAILY)

Future road users - pedestrians and vehicular users - and street furniture, such as signs, can communicate with each other. (PHOTO PROVIDED TO CHINA DAILY)
Private car, a thing of the past

The prevalence of shared transportation will likely lessen the demand for private cars and abate people's desire for buying private cars.

Conventional wisdom holds that private car ownership will become obsolete, which is based on the idea that the next model of transport will be shared mobility, with fleets of cars on call for private users, says Civic Exchange Fellow Jain Alok.

Mobility as a Service (MaaS) will contribute to a decline in private cars, effectively making them obsolete, remarked Alok. People will commute by shared, autonomous cars, instead of driving their own cars. The new form of mobility service is based on a common platform through a single mobile app. The platform allows users to choose their preferred mode of transportation, including autonomous vehicle providers planning your journey and settling payment automatically in one go," Alok explained.

John Zimmer, the president of Lyft, an on-demand transportation company based in San Francisco, made the bold statement two years ago that private automobile ownership will "all but end" in major US cities by 2025. It is a global trend, and true to Hong Kong as well, Alok considered.

The MaaS concept derived from Finland has been accepted and practiced in many cities phase by phase, such as Stockholm, London and Dubai. For example, UbiGo's mobility app was launched in Stockholm in April. The app offers services for car-sharing and ride-riding, rental car services, taxis and shared bikes in one on-demand service. The system is scheduled for a full rollout by the end of this year. Another MaaS pioneer is Germany-based moovel Group, which has provided a MaaS platform since 2015 and attracted 5 million users. Everything connected with users' journey may be managed directly from the platform.

3-D road map generated by a mobile mapping system helps develop smart mobility. (PHOTO PROVIDED TO CHINA DAILY)

App developers in Hong Kong are working feverishly to improve autonomous driving. A mobile mapping system (MMS) developed by Ambit Geospatial Solution can capture road features data in great detail. Eric Yau, a senior manager from Ambit with rich experience in the geospatial discipline, said that "the more data you provide to the navigation system and the more elaborate the data are, the more accurate decisions will the system make". Decisions involve, for example, navigating barriers on road surfaces, detecting lane markings and changing lanes, estimating the position and direction of a moving vehicle, decelerating in the presence of a gradient, and driving at the safest speed on a rainy or snowy day.

The MMS is configured to encompass lidar (light detection and ranging), cameras, sensors and GPS antenna to detect data of objects on the road. Mounted on a car's roof, it cruises on roads to capture traffic data. Then the data are stored in the automatic navigation system so that the system can make more accurate descriptions. Traffic data is complex - a muddled flurry of cars, buses, trucks, pedestrians, lanes and all kinds of road features. Some are predictable and some are not. "With multiple sensors embedded, the MMS is getting more sophisticated and can generate data in finer detail." The technology is crucial to improving the safety of self-driving vehicles, paving the way for self-driving vehicles used as a shared service.

An autonomous vehicle pilot was initiated jointly by Hong Kong Science and Technology Park and the Chinese University of Hong Kong. An autonomous car route between Science Park and University railway station is projected to go into operation within two to three years.
Combat congestion
Evan Auyang (left), chairman of Civic Exchange; Eric Yau, senior GIS manager of Ambit Geospatial Solution. (PHOTO PROVIDED TO CHINA DAILY)

Before private cars disappear from the road, the city has to think hard about methods to keep congestions at bay. Smart technologies are innovated for drivers using heavily congested areas. Appus Technology Ltd, a startup founded in 2014 in Cyberport, specializes in developing smart phone applications for drivers, who can exchange real-time traffic information on the platform with other users within a radius of 500 meters to 5 kilometers, "so that they can change routes, if there are alternatives, in the event of traffic jam ahead of the road". Their OmyCar is one of the most popular apps in the city, downloaded 150,000 times with 85 percent of users being private vehicle drivers.

From a traffic and transport perspective, private vehicles contribute to 50 percent of road traffic in some major roads, but cover only around 10 percent of commuter trips, and are thus considered inefficient passenger carriers, according to the 2030+ Transport Infrastructure and Traffic Review conducted by the Planning Department in 2016.

"Carry capacity" and "flexibility" are key components when it comes to determining whether a means of transport is reliable or not, said Tsang Wing-hang, president of the Chartered Institute of Logistics and Transport Railway. "The railway is the most reliable and efficient transportation system in the city, given that each train can carry up to 3,000 passengers and that trains run as frequently as every two minutes." Besides, the railway network allows alternative lines when emergencies arise, so there's great flexibility, Tsang said. He believes railways will remain the mainstay of the city's transport.

Jain Alok (left), Civic Exchange fellow; Charles So, chairman of Smart Mobility Committee, Smart City Consortium. (PHOTO PROVIDED TO CHINA DAILY)

"With six railway lines due for completion by 2031, the railway network is expected to serve areas inhabited by 75 percent of the local population and about 85 percent of job opportunities within the 500 meters of a railway catchment," said Tsang. Currently, 59 percent of the population lives in metropolitan areas, accounting for 76 percent of the total employment in the city, which suggests that many have to travel long distances to the New Territories to work. "The mismatch between residence and employment will be drastically reduced," he anticipated.

Despite the rosy picture painted by the experts, there're a few regulatory issues that need to be resolved before all private cars are replaced by autonomous vehicles used as shared services. Car-sharing and ride-hailing services are yet to be legalized in the city. The current system of transport requires every passenger-carrying commercial vehicle to carry a license. The vast majority of licenses are given to taxis. As car-sharing and ride-hailing services, such as Uber, come in as a form of "new supply", it takes business away from existing operators and license holders.

Legalization itself is simple, reckoned Auyang of the Civic Exchange, because if the Transport Department really sees that high-quality on-demand private car hires are undersupplied, it may naturally introduce the service via a licensing system. Nevertheless, the issue is not about legalization, it is about managing conflicting interests of different parties, he argued. "It all depends on whether the Transport Department wants to focus on the interests of the traveling public or the interests of operators and owners.
Contact the writer at jenny@chinadailyhk.com

"If new supply like Uber is introduced, there is no way existing stakeholders can be happy. But it's a matter of engagement and consultation to inform them that public interests are at stake, and that they have carefully studied the issue," said Auyang.

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Turning Hong Kong into a smart city has long been on the government's agenda. With smart mobility being the first hands-on experience for the public, experts told Wang Yuke that private cars are the first hurdle in this transformation.

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Charcoal is a lightweight black carbon residue produced by strongly heating wood (or other animal and plant materials) in minimal oxygen to remove all water and volatile constituents. In the traditional version of this pyrolysis process, called charcoal burning, often by forming a charcoal kiln, the heat is supplied by burning part of the starting material itself, with a limited supply of oxygen. The material can also be heated in a closed retort. Modern "charcoal" briquettes used for outdoor cooking may contain many other additives, e.g. coal.

This process happens naturally when combustion is incomplete, and is sometimes used in radiocarbon dating. It also happens inadvertently while burning wood, as in a fireplace or wood stove. The visible flame in these is due to combustion of the volatile gases exuded as the wood turns into charcoal. The soot and smoke commonly given off by wood fires result from incomplete combustion of those volatiles. Charcoal burns at a higher temperature than wood, with hardly a visible flame, and releases almost nothing except heat and carbon dioxide.

The production of wood charcoal in locations where there is an abundance of wood dates back to ancient times. It generally begins with piling billets of wood on their ends to form a conical pile. Openings are left at the bottom to admit air, with a central shaft serving as a flue. The whole pile is covered with turf or moistened clay. The firing is begun at the bottom of the flue, and gradually spreads outward and upward. The success of the operation depends upon the rate of the combustion. Under average conditions wood yields about 60% charcoal by volume, or 25% by weight; small-scale production methods often yield only about 50% by volume, while large-scale methods enabled higher yields of about 90% by the 17th century. The operation is so delicate that it was generally left to colliers (professional charcoal burners). They often lived alone in small huts to tend their wood piles. For example, in the Harz Mountains of Germany, charcoal burners lived in conical huts called which are extant today.

The massive production of charcoal (at its height employing hundreds of thousands, mainly in Alpine and neighbouring forests) was a major cause of deforestation, especially in Central Europe. In England, many woods were managed as coppices, which were cut and regrown cyclically, so that a steady supply of charcoal was available. Complaints (as early as the Stuart period) about shortages may relate to the results of temporary over-exploitation or the impossibility of increasing production to match growing demand. The increasing scarcity of easily harvested wood was a major factor behind the switch to fossil fuel equivalents, mainly coal and brown coal for industrial use.

The modern process of carbonizing wood, either in small pieces or as sawdust in cast iron retorts, is extensively practiced where wood is scarce, and also for the recovery of valuable byproducts ( wood spirit, pyroligneous acid, wood tar), which the process permits. The question of the temperature of the carbonization is important; according to J. Percy, wood becomes brown at 220 °C (430 °F), a deep brown-black after some time at 280 °C (540 °F), and an easily powdered mass at 310 °C (590 °F). Charcoal made at 300 °C (570 °F) is brown, soft and friable, and readily inflames at 380 °C (720 °F); made at higher temperatures it is hard and brittle, and does not fire until heated to about 700 °C (1,300 °F).

In Finland and Scandinavia, the charcoal was considered the by-product of wood tar production. The best tar came from pine, thus pinewoods were cut down for tar pyrolysis. The residual charcoal was widely used as substitute for metallurgical coke in blast furnaces for smelting. Tar production led to rapid local deforestation. The end of tar production at the end of the 19th century resulted in rapid re-forestation of affected areas.

The American form of the charcoal briquette was first invented and patented by Ellsworth B. A. Zwoyer of Pennsylvania in 1897 and was produced by the Zwoyer Fuel Company. The process was further popularized by Henry Ford, who used wood and sawdust byproducts from automobile fabrication as a feedstock. Ford Charcoal went on to become the Kingsford Company.

Charcoal has been made by various methods. The traditional method in Britain used a clamp. This is essentially a pile of wooden logs (e.g. seasoned oak) leaning in a circle against a chimney. The chimney consists of 4 wooden stakes held up by some rope. The logs are completely covered with soil and straw allowing no air to enter. It must be lit by introducing some burning fuel into the chimney; the logs burn very slowly and transform into charcoal over a period of 5 days. If the soil covering gets torn or cracked by the fire, additional soil is placed on the cracks. Once the burn is complete, the chimney is plugged to prevent air from entering. The true art of this production method is in managing the sufficient generation of heat, by combusting part of the wood material, and its transfer to wood parts in the process of being carbonised. A strong disadvantage of this production method is the huge amount of emissions that are harmful to human health and the environment (emissions of unburnt methane). As a result of the partial combustion of wood material, the efficiency of the traditional method is low.

Modern methods employ retorting technology, in which process heat is recovered from, and solely provided by, the combustion of gas released during carbonisation. Yields of retorting are considerably higher than those of kilning, and may reach 35%-40%.

The properties of the charcoal produced depend on the material charred. The charring temperature is also important. Charcoal contains varying amounts of hydrogen and oxygen as well as ash and other impurities that, together with the structure, determine the properties. The approximate composition of charcoal for gunpowders is sometimes empirically described as C ₇H ₄ O. To obtain a coal with high purity, source material should be free of non-volatile compounds.

Wood charcoal is obtained as the residue by destructive distillation of wood such that the products are:

Liquid products - pyroligneous acid and wood tar

Gaseous products - wood gas

Residual product - wood charcoal

Common charcoal is made from peat, coal, wood, coconut shell, or petroleum.

Sugar charcoal is obtained from the carbonization of sugar and is particularly pure. It is purified by boiling with acids to remove any mineral matter and is then burned for a long time in a current of chlorine to remove the last traces of hydrogen. It was used by Henri Moissan in his early attempt to create synthetic diamonds.[citation needed ]

Activated charcoal is similar to common charcoal but is manufactured especially for medical use. To produce activated charcoal, common charcoal is heated to about 900 °C (1,700 °F) in the presence of a gas (usually steam), causing the charcoal to develop many internal spaces, or "pores", which help the activated charcoal to trap chemicals. Impurities on the surface of the charcoal are also removed during this process, greatly increasing its adsorption capacity.

Lump charcoal is a traditional charcoal made directly from hardwood material. It usually produces far less ash than briquettes.

Japanese charcoal has had pyroligneous acid removed during the charcoal making; it therefore produces almost no smell or smoke when burned. The traditional charcoal of Japan is classified into three types:

Pillow shaped briquettes are made by compressing charcoal, typically made from sawdust and other wood by-products, with a binder and other additives. The binder is usually starch. Briquettes may also include brown coal (heat source), mineral carbon (heat source), borax, sodium nitrate (ignition aid), limestone (ash-whitening agent), raw sawdust (ignition aid), and other additives.

Sawdust briquette charcoal is made by compressing sawdust without binders or additives. It is the preferred charcoal in Taiwan, Korea, Greece, and the Middle East. It has a round hole through the center, with a hexagonal intersection. It is used primarily for barbecue as it produces no odour, no smoke, little ash, high heat, and long burning hours (exceeding 4 hours).

Extruded charcoal is made by extruding either raw ground wood or carbonized wood into logs without the use of a binder. The heat and pressure of the extruding process hold the charcoal together. If the extrusion is made from raw wood material, the extruded logs are subsequently carbonized.

Charcoal has been used since earliest times for a large range of purposes including art and medicine, but by far its most important use has been as a metallurgical fuel. Charcoal is the traditional fuel of a blacksmith's forge and other applications where an intense heat is required. Charcoal was also used historically as a source of black pigment by grinding it up. In this form charcoal was important to early chemists and was a constituent of formulas for mixtures such as black powder. Due to its high surface area charcoal can be used as a filter, and as a catalyst or as an adsorbent.

Charcoal burns at temperatures exceeding 1,100 degrees Celsius (2,010 degrees Fahrenheit). By comparison, the melting point of iron is approximately 1,200 to 1,550 °C (2,190 to 2,820 °F). Due to its porosity, it is sensitive to the flow of air and the heat generated can be moderated by controlling the air flow to the fire. For this reason charcoal is still widely used by blacksmiths. Charcoal has been used for the production of iron since Roman times and steel in modern times where it also provided the necessary carbon. Charcoal briquettes can burn up to approximately 1,260 °C (2,300 °F) with a forced air blower forge.

In the 16th century, England had to pass laws to prevent the country from becoming completely denuded of trees due to production of iron. In the 19th century charcoal was largely replaced by coke in steel production due to cost, even though coke usually adds sulphur and sometimes other deleterious contaminants to the pig iron. Wooded metallurgical regions devoid of coal like Sweden, the Urals, or Siberia transitioned from charcoal in the early 20th century.

Historically, charcoal was used in great quantities for smelting iron in bloomeries and later blast furnaces and finery forges. This use was replaced by coal in the 19th Century as part of the Industrial Revolution.

Prior to the Industrial Revolution, charcoal was occasionally used as a cooking fuel. It is counted as a smokeless fuel; that is, the carbon is sufficiently pure that burning it causes substantially less air pollution than burning the original uncarbonized organic material would. In the 20th century, clean-air legislation mandated smokeless fuels (mostly coke or charcoal) in many areas of Europe. In the 21st century, charcoal has been advocated as a way to improve the health of people burning raw biomass for cooking and/or heating. Modern "charcoal" briquettes, widely used for outdoor cooking, are made with charcoal but may also include coal as an energy source as well as accelerants, binders and filler.

To contain the charcoal and use it for cooking purposes, a barbecue grill may be used. A small Japanese charcoal grill is known as a . A brazier is a container used to burn charcoal or other solid fuel.

To start the charcoal burning is harder than starting a wood fire and charcoal lighter fluid may be employed. A chimney starter or electric charcoal starter are tools to help with starting to light charcoal.

Approximately 75% of fuel burned in Haiti is charcoal.

Certain types of charcoal, such as wood charcoal, are used for reducing heated metallic oxides to their respective metals:

Charcoal can also be used to reduce super heated steam to hydrogen (along with the formation of carbon monoxide):

Syngas production, automotive fuel

Like many other sources of carbon, charcoal can be used for the production of various syngas compositions; i.e., various CO + H ₂ + CO ₂ + N ₂ mixtures. The syngas is typically used as fuel, including automotive propulsion, or as a chemical feedstock.

In times of scarce petroleum, automobiles and even buses have been converted to burn wood gas: a gas mixture consisting primarily of diluting atmospheric nitrogen, but also containing combustible gasses (mostly carbon monoxide) released by burning charcoal or wood in a wood gas generator. In 1931, Tang Zhongming developed an automobile powered by charcoal, and these cars were popular in China until the 1950s, and in occupied France during World War II, where they were called .

Charcoal is used in the production of black powder, which is used extensively in the production of fireworks. It is usually ground into a fine powder, with airfloat grade being the finest particle size available commercially. When used in black powder compositions, it is often ball-milled with other ingredients so that they are intimately mixed together. Certain charcoals perform better when used to make black powder, these include spruce, willow, paulownia and grapevine among others. Charcoal produces fine dark orange/golden sparks. Usually, powder with a mesh size from 10 to 325 is used to obtain showers of golden sparks in pyrotechnic compositions.

Charcoal is also incorporated in multiple cosmetic products. It can be produced from regular bamboo cut into small pieces and boiled in water to remove soluble compounds. Raw bamboo charcoal is obtained after drying and carbonization in an oven at elevated temperature. The role of charcoal in cosmetics is based on its highly effective absorbing properties at a microscopic scale.

Charcoal may be used as a source of carbon in chemical reactions. One example of this is the production of carbon disulphide through the reaction of sulfur vapors with hot charcoal. In that case, the wood should be charred at high temperature to reduce the residual amounts of hydrogen and oxygen that lead to side reactions.

Charcoal may be activated to increase its effectiveness as a filter. Activated charcoal readily adsorbs a wide range of organic compounds dissolved or suspended in gases and liquids. In certain industrial processes, such as the purification of sucrose from cane sugar, impurities cause an undesirable color, which can be removed with activated charcoal. It is also used to absorb odors and toxins in gaseous solutions, as in home air purifiers and some types of gas mask. The medical use of activated charcoal is mainly the absorption of poisons. Activated charcoal is available without a prescription, so it is used for a variety of health-related applications. For example, it is often used to reduce discomfort and embarrassment due to excessive gas ( flatulence) in the digestive tract.

Animal charcoal or bone black is the carbonaceous residue obtained by the dry distillation of bones. It contains only about 10% carbon, the remaining being calcium and magnesium phosphates (80%) and other inorganic material originally present in the bones. It is generally manufactured from the residues obtained in the glue and gelatin industries. Its bleaching power was applied in 1812 by Derosne for clarifying sugar syrup, but its use in this direction has now greatly diminished. Today it is seldom used for this purpose due to the introduction of more active and easily managed reagents, but it is still employed to some extent in laboratory practice. The bleaching action of the charcoal in solution diminishes as it adsorbs colored contaminants and it must be reactivated periodically by separate washing and reheating. While wood charcoal effectively removes some pigments and contaminants from solutions, bone charcoal is generally more effective as an adsorption filter due to its increased porosity and surface area.

Charcoal is used for drawing, making rough sketches in painting, and is one of the possible media used for making a parsemage. It usually must be preserved by the application of a fixative. Artists generally utilize charcoal in four forms:

Vine charcoal is created by burning grape vines.

Willow charcoal is created by burning sticks.

Powdered charcoal is often used to "tone" or cover large sections of a drawing surface. Drawing over the toned areas darkens it further, but the artist can also lighten (or completely erase) within the toned area to create lighter tones.

Compressed charcoal is charcoal powder mixed with gum binder and compressed into sticks. The amount of binder determines the hardness of the stick. Compressed charcoal is used in charcoal pencils.

One additional use of charcoal was rediscovered recently for horticulture. Although American gardeners have used charcoal for a short time, research on Terra preta soils in Amazonia has discovered the widespread use of biochar by pre-Columbian natives to ameliorate unproductive soil into soil rich in carbon. The technique may find modern application, both to improve soils and as a means of carbon sequestration.

Charcoal is mixed with feed, added to litter, or used in the treatment of manure. Poultry benefits from using charcoal in this manner.

A concern that activated charcoal might be used unscrupulously to allow livestock to tolerate low quality feed contaminated with aflatoxins resulted in the Association of American Feed Control Officials banning it in 2012 from use in commercial livestock feeds.

Charcoal in the form of charcoal biscuits was consumed in the past for gastric problems. Now it can be consumed in tablet, capsule, or powder form for digestive effects. Research regarding its effectiveness is controversial.

Charcoal has been used in combination with saccharin in research to measure mucociliary transport time.

Charcoal has also been incorporated into toothpaste formulas; however, there is no evidence to determine its safety and effectiveness.

Red colobus monkeys in Africa have been observed eating charcoal for self-medication. Because their leafy diets contain high levels of cyanide, which may lead to indigestion, they learned to consume charcoal, which absorbs the cyanide and relieves discomfort. This knowledge is transmitted from mother to infant.

Production and utilisation of charcoal, like any use of woody biomass as fuel, typically results in emissions and can contribute to deforestation.

The use of charcoal as a smelting fuel has been experiencing a resurgence in South America resulting in severe environmental, social and medical problems. Charcoal production at a sub-industrial level is one of the causes of deforestation. Charcoal production is now usually illegal and nearly always unregulated, as in Brazil, where charcoal production is a large illegal industry for making pig iron.

Massive forest destruction has been documented in areas such as Virunga National Park in the Democratic Republic of Congo, where it is considered a primary threat to the survival of the mountain gorillas. Similar threats are found in Zambia. In Malawi, illegal charcoal trade employs 92,800 workers and is the main source of heat and cooking fuel for 90 percent of the nation's population. Some experts, such as Duncan MacQueen, Principal Researcher-Forest Team, International Institute for Environment and Development (IIED), argue that while illegal charcoal production causes deforestation, a regulated charcoal industry that required replanting and sustainable use of the forests "would give their people clean efficient energy - and their energy industries a strong competitive advantage".

Recent assessments of charcoal imported to Europe have shown that many charcoal products are produced from tropical wood, often of undeclared origin. In an analysis of barbecue charcoal marketed in Germany, the World Wildlife Fund found that most products contain tropical wood. As a notable exception, reference is made to barbecue charcoal imports from Namibia, where charcoal is typically produced from surplus biomass resulting from bush encroachment. Charcoal trafficking in Somalia is an economic and environmental issue with significant regional-security implications.

The last section of the film Le Quattro Volte (2010) gives a good and long, if poetic, documentation of the traditional method of making charcoal. The Arthur Ransome children's series Swallows and Amazons (particularly the second book, Swallowdale) features carefully drawn vignettes of the lives and the techniques of charcoal burners at the start of the 20th century, in the Lake District of the UK. Antonín Dvořák's opera King and Charcoal Burner is based on a Czech legend about a king who gets lost in a forest and is rescued by a charcoal burner.

1. ^ One or more of the preceding sentences incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "Charcoal". Encyclopædia Britannica. Vol. 5 (11th ed.). Cambridge University Press. p. 856.

2. ^ Ray, G.F. (July 1979). "Energy economics - a random walk in history". Energy Economics. 1 (3): 139-143. doi:10.1016/0140-9883(79)90044-6.

3. ^ "Geoarch". Geoarch. 31 May 1999. Archived from the original on 15 March 2004.

4. ^ "Roland.V. Siemons, Loek Baaijens, An Innovative Carbonisation Retort: Technology and Environmental Impact, TERMOTEHNIKA, 2012, XXXVIII, 2, 131‡138 131" (PDF).

5. ^ "Kilning vs. Retorting: the cause of emissions of unburnt gases".

6. ^ Cheng, Zhilong; Yang, Jian; Zhou, Lang; Liu, Yan; Wang, Qiuwang (1 January 2016). "Characteristics of charcoal combustion and its effects on iron-ore sintering performance". Applied Energy. 161: 364-374. doi:10.1016/j.apenergy.2015.09.095. ISSN 0306-2619.

7. ^ Kenneth L. Kosanke; Bonnie J. Kosanke (1999), "Pyrotechnic Spark Generation", Journal of Pyrotechnics: 49-62, ISBN 978-1-889526-12-6, archived from the original on 16 December 2017

8. ^ Ahmad, N; Isa, S.S.M.; Ramli, M.M.; Hambali, N.A.M.A.; Kasjoo, S.R.; Isa, M.M.; Nor, N.I.M.; Khalid, N. (2016). "Adsorption properties and potential applications of bamboo charcoal: A Review" (PDF). MATEC Web of Conferences. 78: 1-7. Archived from the original (PDF) on 24 July 2018 - via edp sciences.

9. ^ Dawson, Andrew (1997). "Activated charcoal: a spoonful of sugar". Australian Prescriber. 20: 14-16. doi:10.18773/austprescr.1997.008.

10. ^ "Treating flatulence". NHS. NHS UK.

11. ^ Johannes Lehmann, ed. (2009). Biochar for Environmental Management: Science and Technology. Stephen Joseph. Earthscan. ISBN 978-1-84407-658-1.

12. ^ Gerlach, Achim; Schmidt, Hans-Peter (2014), "The use of biochar in cattle farming", The Biochar Journal, Arbaz, Switzerland, ISSN 2297-1114

13. ^ Yarrow, David (March 2015). "Biochar: Helping Everything from Soil Fertility to Odor Reduction". Acres U.S.A. Archived from the original on 9 June 2019.

14. ^ Schupska Site=CAES News, Stephanie (10 March 2011). "Charcoal supplemented diet reduces ammonia in chickens' litter".

15. ^ Damerow, Gail (2015). The Chicken Health Handbook, 2nd Edition: A Complete Guide to Maximizing Flock Health and Dealing with Disease. p. 391. ISBN 978-1612120133.

16. ^ Stearn, Margaret (2007). Warts and all: straight talking advice on life's embarrassing problems. London: Murdoch Books. p. 333. ISBN 978-1-921259-84-5.

17. ^ Am J Gastroenterology 2005 Feb 100(2)397-400 and 1999 Jan 94(1) 208-12

18. ^ Passali, Desiderio (1984). "Experiences in the determination of nasal mucociliary transport time". Acta Otolaryngol. 97 (3-4): 319-23. doi:10.3109/00016488409130995. PMID 6539042.

19. ^ Brooks, John K.; Bashirelahi, Nasir; Reynolds, Mark A. (7 June 2017). "Charcoal and charcoal-based dentifrices: A literature review". Journal of the American Dental Association. 148 (9): 661-670. doi:10.1016/j.adaj.2017.05.001. ISSN 1943-4723. PMID 28599961.

20. ^ M. Kato1, D. M. DeMarini, A. B. Carvalho, M. A. V. Rego, A. V. Andrade1, A. S. V. Bonfim and D. Loomis (2004). "World at work: Charcoal producing industries in northeastern Brazil". Occupational and Environmental Medicine. 62 (2): 128-132. doi:10.1136/oem.2004.015172. PMC 1740946. PMID 15657196. Archived from the original on 22 November 2012.

21. ^ "Driving Destruction in the Amazon: How steel production is throwing the forest into the furnace". Greenpeace. 11 May 2012. Archived from the original on 20 May 2012.

22. The documentary film ^ The Charcoal People (2000) [1] shows in detail the deforestation in Brazil, the poverty of the laborers and their families, and the method of constructing and using a clamp for burning the wood.

23. ^ "Virunga National Park". Gorilla.cd. Archived from the original on 3 October 2008.

24. ^

25. ^ Zahnen, Johannes. "Market Analysis Barbecue Charcoal 2018 - The Dirty Business of Barbecue Charcoal" (PDF). WWF.

26. ^ "From Bush to Charcoal: the Greenest Charcoal Comes from Namibia". Forest Stewardship Council. 17 March 2020.

27. ^ Gridneff, Ilya (2018). "Burning Somalia's Future: The Illegal Charcoal Trade Between the Horn of Africa and the Gulf". In Verhoeven, Harry (ed.). Environmental Politics in the Middle East. Oxford: Oxford University Press. pp. 121-148. ISBN 9780190916688.

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Charcoal is a lightweight black carbon residue produced by strongly heating wood (or other animal and plant materials) in minimal oxygen to remove all water and volatile constituents. In the traditional version of this pyrolysis process, called charcoal burning, often by forming a charcoal kiln, the heat is supplied by burning part of the starting material itself, with a limited supply of oxygen.

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The ESG Challenges for Transition Metals

An accelerated energy transition is needed to respond to climate change.

According to the Paris Agreement, 196 countries have already committed to limiting global warming to below 2°C, preferably 1.5°C. However, changing the energy system after over a century of burning fossil fuels comes with challenges.

In the above graphic from our sponsor Wood Mackenzie, we discuss the challenges that come with the increasing demand for transition metals.

Building Blocks of a Decarbonized World

Mined commodities like lithium, cobalt, graphite and rare earths are critical to producing electric vehicles (EVs), wind turbines, and other technologies necessary to burn fewer fossil fuels and reduce overall carbon emissions.

EVs, for example, can have up to six times more minerals than a combustion vehicle.

As a result, the extraction and refining of these metals will need to be expedited to limit the rise of global temperatures.

Here's the outlook for different metals under Wood Mackenzie's Accelerated Energy Transition (AET) scenario, in which the world is on course to limit the rise in global temperatures since pre-industrial times to 1.5°C by the end of this century.

Graphite demand is expected to soar 1,100% by 2040, as demand for lithium is expected to jump 940% over this time.

A Challenge to Satisfy the Demand for Lithium

Lithium-ion batteries are indispensable for transport electrification and are also commonly used in cell phones, laptop computers, cordless power tools, and other devices.

Lithium demand in an AET scenario is estimated to reach 6.7 million tons by 2050, nine times more than 2022 levels.

In the same scenario, EV sales will double by 2030, making the demand for Li-ion batteries quadruple by 2050.

The ESG Challenge with Cobalt

Another metal in high demand is cobalt, used in rechargeable batteries in smartphones and laptops and also in lithium-ion batteries for vehicles.

Increasing production comes with significant environmental and social risks, as cobalt reserves and mine production are concentrated in regions and countries with substantial ESG problems.

Currently, 70% of mined cobalt comes from the Democratic Republic of Congo, where nearly three-quarters of the population lives in extreme poverty.

Around one-fifth of cobalt mined in the DRC comes from small-scale artisanal mines, many of which rely on child labor.

Considering other obstacles like rising costs due to reserve depletion and surging resource nationalism, a shortfall in the cobalt market can emerge as early as 2024, according to Wood Mackenzie. Battery recycling, if fully utilised, can ease the upcoming supply shortage, but it cannot fill the entire gap.

Rare Earths: Winners and Losers

Rare earths are used in EVs and wind turbines but also in petroleum refining and gas vehicles. Therefore, an accelerated energy transition presents a mixed bag.

Using permanent magnets in applications like electric motors, sensors, and magnetic recording and storage media is expected to boost demand for materials like neodymium (Nd) and praseodymium (Pr) oxide.

On the contrary, as the world shifts from gas vehicles to EVs, declining demand from catalytic converters in fossil fuel-powered vehicles will impact lanthanum (La) and cerium (Ce).

Taking all into consideration, the demand for rare earths in an accelerated energy transition is forecasted to increase by 233% between 2020 and 2050. In this scenario, existing producers would be impacted by a short- to medium-term supply deficit.

The ESG dilemma

There is a clear dilemma for energy transition metals in an era of unprecedented demand. Can vital energy transition metals markets ramp up production fast enough to satisfy demand, while also revolutionising supply chains to meet ever-more stringent ESG requirements?

Understanding the challenges and how to capitalise on this investment opportunity has become more important than ever.

Sign up to to learn more about the impact of an accelerated energy transition on mining and metals.

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Visualizing the Scale of Global Fossil Fuel Production

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An accelerated energy transition is needed to respond to climate change. According to the Paris Agreement, 196 countries have already committed to limiting global warming to below 2°C, preferably 1.5°C. However, changing the energy system after over a century of burning fossil fuels comes with challenges.

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- The human population increases violently. By the end of the 21st century, most of the urbanisation on our planet is likely to be completed.
How are some cities successful:
- population growth
- economic performance
- a functional organisation

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How does air pollution harm the human population?

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How does air pollution harm the human population?

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Air pollution is a familiar environmental health hazard. We know what we’re looking at when brown haze settles over a city, exhaust billows across a busy highway or a plume rise from a smokestack. Some air pollution is not seen, but its pungent smell alerts you.

It is a major threat to global health and prosperity. Air pollution caused 6.5 million deaths each year globally, a number that has increased over the past two decades.

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National Institute of Environmental Health Sciences

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Introduction

Air pollution is a familiar environmental health hazard. We know what we're looking at when brown haze settles over a city, exhaust billows across a busy highway, or a plume rises from a smokestack. Some air pollution is not seen, but its pungent smell alerts you.

It is a major threat to global health and prosperity. Air pollution, in all forms, is responsible for more than 6.5 million deaths each year globally, a number that has increased over the past two decades.

What Is Air Pollution?

Air pollution is a mix of hazardous substances from both human-made and natural sources.

Vehicle emissions, fuel oils and natural gas to heat homes, by-products of manufacturing and power generation, particularly coal-fueled power plants, and fumes from chemical production are the primary sources of human-made air pollution.

Nature releases hazardous substances into the air, such as smoke from wildfires, which are often caused by people; ash and gases from volcanic eruptions; and gases, like methane, which are emitted from decomposing organic matter in soils.

Traffic-Related Air Pollution (TRAP), a mixture of gasses and particles, has most of the elements of human-made air pollution: ground-level ozone, various forms of carbon, nitrogen oxides, sulfur oxides, volatile organic compounds, polycyclic aromatic hydrocarbons, and fine particulate matter.

Ozone, an atmospheric gas, is often called smog when at ground level. It is created when pollutants emitted by cars, power plants, industrial boilers, refineries, and other sources chemically react in the presence of sunlight.

Noxious gases, which include carbon dioxide, carbon monoxide, nitrogen oxides (NOx), and sulfur oxides (SOx), are components of motor vehicle emissions and byproducts of industrial processes.

Particulate matter (PM) is composed of chemicals such as sulfates, nitrates, carbon, or mineral dusts. Vehicle and industrial emissions from fossil fuel combustion, cigarette smoke, and burning organic matter, such as wildfires, all contain PM.

A subset of PM, fine particulate matter (PM 2.5) is 30 times thinner than a human hair. It can be inhaled deeply into lung tissue and contribute to serious health problems. PM 2.5 accounts for most health effects due to air pollution in the U.S.

Volatile organic compounds (VOC) vaporize at or near room temperature-hence, the designation volatile. They are called organic because they contain carbon. VOCs are given off by paints, cleaning supplies, pesticides, some furnishings, and even craft materials like glue. Gasoline and natural gas are major sources of VOCs, which are released during combustion.

Polycyclic aromatic hydrocarbons (PAH) are organic compounds containing carbon and hydrogen. Of more than 100 PAHs known to be widespread in the environment, 15 are listed in the Report on Carcinogens. In addition to combustion, many industrial processes, such as iron, steel, and rubber product manufacturing, as well as power generation, also produce PAHs as a by-product. PAHs are also found in particulate matter.

Air Pollution and Climate Change

Air pollution and climate change affect each other through complex interactions in the atmosphere. Air pollution is intricately linked with climate change because both problems come largely from the same sources, such as emissions from burning fossil fuels. Both are threats to people's health and the environment worldwide. Read more: Health Impacts of Air Quality.

What Is NIEHS Doing?

Over its 50-plus year history, NIEHS has been a leader in air pollution research. The institute continues to fund and conduct research into how air pollution affects health and the population groups who are most affected.

How does air pollution affect our health?

When the National Ambient Air Quality Standards were established in 1970, air pollution was regarded primarily as a threat to respiratory health. In 1993, NIEHS researchers published the landmark Six Cities Study, which established an association between fine particulate matter and mortality.

Air pollution exposure is associated with oxidative stress and inflammation in human cells, which may lay a foundation for chronic diseases and cancer. In 2013, the International Agency for Research on Cancer of the World Health Organization (WHO) classified air pollution as a human carcinogen.

Mortality rates related to air pollution are a concern. Exposure to the air pollutant PM2.5 is associated with an increased risk of death.

A team of researchers, partially funded by NIEHS, found that deaths decreased after air pollution regulations were implemented and coal-powered plants were retired. The study data covered 21 years. More specifically, they found exposure to PM2.5 from coal was associated with a mortality risk that was twice as high as the risk from exposure to PM2.5 from all sources. PM2.5 from coal is high in sulfur dioxide, black carbon, and metals.

Public health concerns include cancer, cardiovascular disease, respiratory diseases, diabetes mellitus, obesity, and reproductive, neurological, and immune system disorders.

Research on air pollution and health effects continually advances.

Cancer

A large study of more than 57,000 women found living near major roadways may increase a woman's risk for breast cancer.

The NIEHS Sister Study found other airborne toxic substances, especially methylene chloride, which is used in aerosol products and paint removers, are also associated with increased risk of breast cancer.

Occupational exposure to benzene, an industrial chemical and component of gasoline, can cause leukemia and is associated with non-Hodgkin's Lymphoma.

A long-term study, 2000-2016, found an association between lung cancer incidence and increased reliance on coal for energy generation.

Cardiovascular Disease

Fine particulate matter can impair blood vessel function and speed up calcification in arteries.

NIEHS researchers established links between short-term daily exposure by post-menopausal women to nitrogen oxides and increased risk of hemorrhagic stroke.

For some older Americans, exposure to TRAP can result in lowered levels of high-density lipoprotein, sometimes called good cholesterol, increasing their risk for cardiovascular disease.

According to a National Toxicology Program (NTP) , TRAP exposure also increases a pregnant woman's risk for dangerous changes in blood pressure, known as hypertensive disorders, which are a leading cause of pre-term birth, low birth weight, and maternal and fetal illness and death.

Respiratory Disease

Air pollution can affect lung development and is implicated in the development of , asthma, and other respiratory diseases, such as chronic obstructive pulmonary disease (COPD).

Increases in asthma prevalence and severity are linked to urbanization and outdoor air pollution. Children living in low-income urban areas tend to have more asthma cases than others. Research published in 2023 tied two air pollutants, ozone and PM2.5, to asthma-related changes in children's airways.

PM and nitrogen oxide are linked to chronic bronchitis.

In 2020, a major public health challenge was confluence of the COVID-19 pandemic and wildfires across the western U.S. Building on a well-established connection between air pollution and respiratory-tract infections, a study linked wildfire smoke with additional COVID-19 cases and deaths.

Whom does air pollution affect the most?

Air pollution affects everyone's health, but certain groups may be harmed more.
Almost 9 out of 10 people who live in urban areas worldwide are affected by air pollution.
Children
The NIEHS-funded Children's Health Study at the University of Southern California is one of the largest studies of the long-term effects of air pollution on children's respiratory health. Among its findings:

Higher air pollution levels increase short-term respiratory infections, which lead to more school absences.

Children who play several outdoor sports and live in high ozone communities are more likely to develop asthma.

Children living near busy roads are at increased risk for asthma.

Children with asthma who were exposed to high levels of air pollutants were more likely to develop bronchitis symptoms.

Living in communities with higher pollution levels can cause lung damage.

Other studies on women and children

NIEHS-funded researchers from the University of California, Davis, Environmental Health Sciences Center are conducting the Bio-Specimen and Fire Effects (B-SAFE) Study. This ongoing project seeks to discover if and how recent wildfires and their smoke affected pregnant women and their babies. Begun in 2017, study participants are pregnant women who were living in Northern California when the 2018, 2019, or 2020 wildfires occurred there.

Breathing PM 2.5, even at relatively low levels, may alter the size of a child's developing brain, which may ultimately increase the risk for cognitive and emotional problems later in adolescence.

Prenatal exposure to PAHs was associated with brain development effects, slower processing speed, attention-deficit and hyperactivity disorder (ADHD) symptoms, and other neurobehavioral problems in urban youth.

In New York City, prenatal exposure to air pollution may play a role in childhood ADHD-related behavior problems.

Prenatal exposure to particulate matter was associated with low birth weight.

Women exposed to high levels of fine particulate matter during pregnancy, particularly in the third trimester, may have up to twice the risk of having a child with autism.

Second and third trimester exposure to PM 2.5 might increase the chance of those children having high blood pressure in early life.

In California's agricultural San Joaquin Valley, women who were exposed to high levels of carbon monoxide, nitrogen oxide, or nitrogen dioxide during their first 8 weeks of pregnancy were more likely to have a baby with neural tube defects.

In Marietta, Ohio, home to a ferromanganese refinery, manganese concentrations in blood and hair, a biomarker of air pollution exposure, were associated with lower child IQ scores.

Older adults

Alzheimer's disease and related dementias are a public health challenge for aging populations. NIEHS-funded researchers at the University of Washington identified a link between air pollution and dementias. This well-conducted study adds considerable evidence that ambient air fine particles increase risk of dementias. Conversely, a multi-year study published in 2022 shows improved air quality is associated with lower risk of dementia in older women. The researchers also stated this decline in dementia risk was equivalent to taking nearly 2 1/2 years off the age of the women studied.

Air pollution was linked to a greater chance of developing several neurological disorders, including Parkinson's disease, Alzheimer's disease, and other dementias. Hospital admissions data from 63 million older adults in the U.S., obtained over 17 years (2000-2016), was analyzed along with estimated PM 2.5 concentrations by zip code to conduct the study.

In older adults, long-term exposure to TRAP may significantly hasten physical disabilities. The risk is more pronounced among racial minorities and lower-income people.

Osteoporosis affects women more than men. A large study associated high levels of air pollutants with bone damage, particularly in the lumbar spine, among postmenopausal women. This study expands previous findings linking air pollution and bone damage.

Nutrients may counter some harmful effects from air pollution. A 2020 study found omega-3 fatty acids, obtained by eating certain fish, may protect against PM 2.5-associated brain shrinkage in older women.

Rural dwellers

An NIEHS-funded study found that concentrations of PM 2.5 in rural Washington State were comparable to urban Seattle. In this study, as regional PM 2.5 increased, there were increased asthma symptoms, such as limitation of activities, more wheezing, and more nighttime waking, in rural children.

NIEHS supported a translational research project, Addressing Air Pollution and Asthma (1MB) , that may lead to improved health for children suffering from asthma. They found that certain agricultural practices contribute to poor air quality and asthma among children. The team combined high-efficiency particulate air (HEPA) cleaners and a home-based education program to reduce children's exposure to pollutants in the home.

In the rural U.S., large-scale animal feeding operations might compromise regional air quality through emission of pollutants, such as ammonia gas. A study found acute lung function problems in children with asthma in such areas.

Different genes
Your genes play a role in respiratory health. NIEHS-funded research discovered that people with specific gene variants, which made them more likely to have lung inflammation, had a greater chance of suffering from asthma if they lived close to major roadways.

NIEHS and community involvement

NIEHS supports community participation in the research process and encourages collaborative approaches that build capacity in communities to address environmental health concerns. Community-engaged research and citizen science are two types of collaborative research approaches.

For example, NIEHS helps residents of Imperial County, California track air pollution through a network of 40 community-run monitors. In this county, long-term improvements in air quality were associated with significant lung-function improvement in children.

In another example, NIEHS grant recipients developed community-level tactics and public policies for reducing exposure to TRAP:

Using high-efficiency particulate air (HEPA) filtration.

Building land-use buffers and vegetation barriers.

Improving urban design with gardens, parks, and street-side trees.

Creating active-travel options, such as bicycling and walking paths.

THE (Trade, Health, Environment) Impact Project brings together researchers and community groups to find solutions for communities affected by trade-related pollution, such as ports and roadways with trucking.

Join an asthma study!

The goal of the Natural History of Asthma with Longitudinal Environmental Sampling (NHALES) study is to help scientists understand how bacteria and other factors in the environment affect people who have moderate to severe asthma.

Who can participate?

Moderate to severe asthmatics.

Males and females, aged 18-60.

Females should not be pregnant or breastfeeding at the start of the study, but may still participate if they become pregnant during the study.

Nonsmokers who are also not around significant amounts of secondhand smoke.

No history of chronic obstructive pulmonary disease, emphysema, cystic fibrosis (CF), pulmonary fibrosis, non-CF bronchiectasis, sarcoidosis, unstable angina, or pulmonary hypertension.

Not allergic to methacholine.

Able to provide your own transportation to clinic visits on the NIEHS campus in North Carolina.

For more information about this study:

NHALES: Asthma Study

Tel 855-MYNIEHS (855-696-4347)
nhales@mail.nih.gov

Why improving air quality matters

Air pollution and birth outcomes are linked as global public health concerns. Researchers analyzed indoor and outdoor air pollution data from all inhabited continents along with key pregnancy outcomes. Their findings indicate efforts to reduce PM2.5 exposure could lead to significant reductions in the number of low-birth weight and pre-term birth infants worldwide. Air pollution reduction would be especially beneficial for children born in low- and middle-income countries.

Among children in Southern California, decreases in ambient nitrogen dioxide and PM 2.5 were associated with fewer cases of asthma.

An NIEHS-funded study found that a mixture of several B vitamins may protect DNA from changes attributable to PM 2.5 air pollution.

Bronchitis symptoms declined as pollution levels dropped in the Los Angeles region.

Improving air quality may improve cognitive function and reduce dementia risk, according to supported in part by NIH and the Alzheimer's Association.

When fossil-fuel power plants close, nearby air pollution is reduced. A study found the incidence of preterm births went down within 5 kilometers of retired coal and oil-powered plant locations.

Further Reading

Stories from the Environmental Factor (NIEHS newsletter)

Printable Fact Sheets

Podcasts

Additional Resources

Air Pollution Linked to Dementia Cases (September 2023) - In this edition of NIH Research Matters, read about findings from the Health and Retirement Study, funded by the National Institute on Aging, that showed higher air pollution exposure was linked to an increased risk of dementia. After consideration of all sources, fine particulate matter, or PM2.5, from agriculture and wildfires were specifically associated with an increased risk of dementia. Reducing such exposures might help lower the incidence of dementia. The study was published in JAMA Internal Medicine.

, a tool developed in partnership by several government agencies, allows you to monitor air quality in real time anywhere in the U.S. Simply enter your zip code as indicated on the website.

EPA's Air Sensor Toolbox provides information on the operation and use of air-sensor monitoring systems for technology developers, air-quality managers, citizen scientists, and the public.

NIH Climate Change and Health Initiative - This solutions-focused research initiative aims to reduce the health consequences associated with extreme weather events and evolving climate conditions. NIH has a strong history of creating innovative tools, technologies, and data-driven solutions to address global environmental problems.

Smoke-ready Toolbox for Wildfires is a compendium of resources from the EPA to help educate you about the risks of smoke exposure and actions that protect your health.

Wildfire Smoke Collection - The journal Environmental Health Perspectives has published high-impact papers and reviews exploring exposure and resulting health effects related to wildfires.

Related Health Topics

This content is available to use on your website.

Please visit NIEHS Syndication to get started.

Introduction

Air pollution is a familiar environmental health hazard. We know what we're looking at when brown haze settles over a city, exhaust billows across a busy highway, or a plume rises from a smokestack. Some air pollution is not seen, but its pungent smell alerts you.

It is a major threat to global health and prosperity. Air pollution, in all forms, is responsible for more than 6.5 million deaths each year globally, a number that has increased over the past two decades.

What Is Air Pollution?

Air pollution is a mix of hazardous substances from both human-made and natural sources.

Vehicle emissions, fuel oils and natural gas to heat homes, by-products of manufacturing and power generation, particularly coal-fueled power plants, and fumes from chemical production are the primary sources of human-made air pollution.

Nature releases hazardous substances into the air, such as smoke from wildfires, which are often caused by people; ash and gases from volcanic eruptions; and gases, like methane, which are emitted from decomposing organic matter in soils.

Traffic-Related Air Pollution (TRAP), a mixture of gasses and particles, has most of the elements of human-made air pollution: ground-level ozone, various forms of carbon, nitrogen oxides, sulfur oxides, volatile organic compounds, polycyclic aromatic hydrocarbons, and fine particulate matter.

Ozone, an atmospheric gas, is often called smog when at ground level. It is created when pollutants emitted by cars, power plants, industrial boilers, refineries, and other sources chemically react in the presence of sunlight.

Noxious gases, which include carbon dioxide, carbon monoxide, nitrogen oxides (NOx), and sulfur oxides (SOx), are components of motor vehicle emissions and byproducts of industrial processes.

Particulate matter (PM) is composed of chemicals such as sulfates, nitrates, carbon, or mineral dusts. Vehicle and industrial emissions from fossil fuel combustion, cigarette smoke, and burning organic matter, such as wildfires, all contain PM.

A subset of PM, fine particulate matter (PM 2.5) is 30 times thinner than a human hair. It can be inhaled deeply into lung tissue and contribute to serious health problems. PM 2.5 accounts for most health effects due to air pollution in the U.S.

Volatile organic compounds (VOC) vaporize at or near room temperature-hence, the designation volatile. They are called organic because they contain carbon. VOCs are given off by paints, cleaning supplies, pesticides, some furnishings, and even craft materials like glue. Gasoline and natural gas are major sources of VOCs, which are released during combustion.

Polycyclic aromatic hydrocarbons (PAH) are organic compounds containing carbon and hydrogen. Of more than 100 PAHs known to be widespread in the environment, 15 are listed in the Report on Carcinogens. In addition to combustion, many industrial processes, such as iron, steel, and rubber product manufacturing, as well as power generation, also produce PAHs as a by-product. PAHs are also found in particulate matter.

Air Pollution and Climate Change

Air pollution and climate change affect each other through complex interactions in the atmosphere. Air pollution is intricately linked with climate change because both problems come largely from the same sources, such as emissions from burning fossil fuels. Both are threats to people's health and the environment worldwide. Read more: Health Impacts of Air Quality.

What Is NIEHS Doing?

Over its 50-plus year history, NIEHS has been a leader in air pollution research. The institute continues to fund and conduct research into how air pollution affects health and the population groups who are most affected.

How does air pollution affect our health?

When the National Ambient Air Quality Standards were established in 1970, air pollution was regarded primarily as a threat to respiratory health. In 1993, NIEHS researchers published the landmark Six Cities Study, which established an association between fine particulate matter and mortality.

Air pollution exposure is associated with oxidative stress and inflammation in human cells, which may lay a foundation for chronic diseases and cancer. In 2013, the International Agency for Research on Cancer of the World Health Organization (WHO) classified air pollution as a human carcinogen.

Mortality rates related to air pollution are a concern. Exposure to the air pollutant PM2.5 is associated with an increased risk of death.

A team of researchers, partially funded by NIEHS, found that deaths decreased after air pollution regulations were implemented and coal-powered plants were retired. The study data covered 21 years. More specifically, they found exposure to PM2.5 from coal was associated with a mortality risk that was twice as high as the risk from exposure to PM2.5 from all sources. PM2.5 from coal is high in sulfur dioxide, black carbon, and metals.

Public health concerns include cancer, cardiovascular disease, respiratory diseases, diabetes mellitus, obesity, and reproductive, neurological, and immune system disorders.

Research on air pollution and health effects continually advances.

Cancer

A large study of more than 57,000 women found living near major roadways may increase a woman's risk for breast cancer.

The NIEHS Sister Study found other airborne toxic substances, especially methylene chloride, which is used in aerosol products and paint removers, are also associated with increased risk of breast cancer.

Occupational exposure to benzene, an industrial chemical and component of gasoline, can cause leukemia and is associated with non-Hodgkin's Lymphoma.

A long-term study, 2000-2016, found an association between lung cancer incidence and increased reliance on coal for energy generation.

Cardiovascular Disease

Fine particulate matter can impair blood vessel function and speed up calcification in arteries.

NIEHS researchers established links between short-term daily exposure by post-menopausal women to nitrogen oxides and increased risk of hemorrhagic stroke.

For some older Americans, exposure to TRAP can result in lowered levels of high-density lipoprotein, sometimes called good cholesterol, increasing their risk for cardiovascular disease.

According to a National Toxicology Program (NTP) , TRAP exposure also increases a pregnant woman's risk for dangerous changes in blood pressure, known as hypertensive disorders, which are a leading cause of pre-term birth, low birth weight, and maternal and fetal illness and death.

Respiratory Disease

Air pollution can affect lung development and is implicated in the development of , asthma, and other respiratory diseases, such as chronic obstructive pulmonary disease (COPD).

Increases in asthma prevalence and severity are linked to urbanization and outdoor air pollution. Children living in low-income urban areas tend to have more asthma cases than others. Research published in 2023 tied two air pollutants, ozone and PM2.5, to asthma-related changes in children's airways.

PM and nitrogen oxide are linked to chronic bronchitis.

In 2020, a major public health challenge was confluence of the COVID-19 pandemic and wildfires across the western U.S. Building on a well-established connection between air pollution and respiratory-tract infections, a study linked wildfire smoke with additional COVID-19 cases and deaths.

Whom does air pollution affect the most?

Air pollution affects everyone's health, but certain groups may be harmed more.
Almost 9 out of 10 people who live in urban areas worldwide are affected by air pollution.
Children
The NIEHS-funded Children's Health Study at the University of Southern California is one of the largest studies of the long-term effects of air pollution on children's respiratory health. Among its findings:

Higher air pollution levels increase short-term respiratory infections, which lead to more school absences.

Children who play several outdoor sports and live in high ozone communities are more likely to develop asthma.

Children living near busy roads are at increased risk for asthma.

Children with asthma who were exposed to high levels of air pollutants were more likely to develop bronchitis symptoms.

Living in communities with higher pollution levels can cause lung damage.

Other studies on women and children

NIEHS-funded researchers from the University of California, Davis, Environmental Health Sciences Center are conducting the Bio-Specimen and Fire Effects (B-SAFE) Study. This ongoing project seeks to discover if and how recent wildfires and their smoke affected pregnant women and their babies. Begun in 2017, study participants are pregnant women who were living in Northern California when the 2018, 2019, or 2020 wildfires occurred there.

Breathing PM 2.5, even at relatively low levels, may alter the size of a child's developing brain, which may ultimately increase the risk for cognitive and emotional problems later in adolescence.

Prenatal exposure to PAHs was associated with brain development effects, slower processing speed, attention-deficit and hyperactivity disorder (ADHD) symptoms, and other neurobehavioral problems in urban youth.

In New York City, prenatal exposure to air pollution may play a role in childhood ADHD-related behavior problems.

Prenatal exposure to particulate matter was associated with low birth weight.

Women exposed to high levels of fine particulate matter during pregnancy, particularly in the third trimester, may have up to twice the risk of having a child with autism.

Second and third trimester exposure to PM 2.5 might increase the chance of those children having high blood pressure in early life.

In California's agricultural San Joaquin Valley, women who were exposed to high levels of carbon monoxide, nitrogen oxide, or nitrogen dioxide during their first 8 weeks of pregnancy were more likely to have a baby with neural tube defects.

In Marietta, Ohio, home to a ferromanganese refinery, manganese concentrations in blood and hair, a biomarker of air pollution exposure, were associated with lower child IQ scores.

Older adults

Alzheimer's disease and related dementias are a public health challenge for aging populations. NIEHS-funded researchers at the University of Washington identified a link between air pollution and dementias. This well-conducted study adds considerable evidence that ambient air fine particles increase risk of dementias. Conversely, a multi-year study published in 2022 shows improved air quality is associated with lower risk of dementia in older women. The researchers also stated this decline in dementia risk was equivalent to taking nearly 2 1/2 years off the age of the women studied.

Air pollution was linked to a greater chance of developing several neurological disorders, including Parkinson's disease, Alzheimer's disease, and other dementias. Hospital admissions data from 63 million older adults in the U.S., obtained over 17 years (2000-2016), was analyzed along with estimated PM 2.5 concentrations by zip code to conduct the study.

In older adults, long-term exposure to TRAP may significantly hasten physical disabilities. The risk is more pronounced among racial minorities and lower-income people.

Osteoporosis affects women more than men. A large study associated high levels of air pollutants with bone damage, particularly in the lumbar spine, among postmenopausal women. This study expands previous findings linking air pollution and bone damage.

Nutrients may counter some harmful effects from air pollution. A 2020 study found omega-3 fatty acids, obtained by eating certain fish, may protect against PM 2.5-associated brain shrinkage in older women.

Rural dwellers

An NIEHS-funded study found that concentrations of PM 2.5 in rural Washington State were comparable to urban Seattle. In this study, as regional PM 2.5 increased, there were increased asthma symptoms, such as limitation of activities, more wheezing, and more nighttime waking, in rural children.

NIEHS supported a translational research project, Addressing Air Pollution and Asthma (1MB) , that may lead to improved health for children suffering from asthma. They found that certain agricultural practices contribute to poor air quality and asthma among children. The team combined high-efficiency particulate air (HEPA) cleaners and a home-based education program to reduce children's exposure to pollutants in the home.

In the rural U.S., large-scale animal feeding operations might compromise regional air quality through emission of pollutants, such as ammonia gas. A study found acute lung function problems in children with asthma in such areas.

Different genes
Your genes play a role in respiratory health. NIEHS-funded research discovered that people with specific gene variants, which made them more likely to have lung inflammation, had a greater chance of suffering from asthma if they lived close to major roadways.

NIEHS and community involvement

NIEHS supports community participation in the research process and encourages collaborative approaches that build capacity in communities to address environmental health concerns. Community-engaged research and citizen science are two types of collaborative research approaches.

For example, NIEHS helps residents of Imperial County, California track air pollution through a network of 40 community-run monitors. In this county, long-term improvements in air quality were associated with significant lung-function improvement in children.

In another example, NIEHS grant recipients developed community-level tactics and public policies for reducing exposure to TRAP:

Using high-efficiency particulate air (HEPA) filtration.

Building land-use buffers and vegetation barriers.

Improving urban design with gardens, parks, and street-side trees.

Creating active-travel options, such as bicycling and walking paths.

THE (Trade, Health, Environment) Impact Project brings together researchers and community groups to find solutions for communities affected by trade-related pollution, such as ports and roadways with trucking.

Join an asthma study!

The goal of the Natural History of Asthma with Longitudinal Environmental Sampling (NHALES) study is to help scientists understand how bacteria and other factors in the environment affect people who have moderate to severe asthma.

Who can participate?

Moderate to severe asthmatics.

Males and females, aged 18-60.

Females should not be pregnant or breastfeeding at the start of the study, but may still participate if they become pregnant during the study.

Nonsmokers who are also not around significant amounts of secondhand smoke.

No history of chronic obstructive pulmonary disease, emphysema, cystic fibrosis (CF), pulmonary fibrosis, non-CF bronchiectasis, sarcoidosis, unstable angina, or pulmonary hypertension.

Not allergic to methacholine.

Able to provide your own transportation to clinic visits on the NIEHS campus in North Carolina.

For more information about this study:

NHALES: Asthma Study

Tel 855-MYNIEHS (855-696-4347)
nhales@mail.nih.gov

Why improving air quality matters

Air pollution and birth outcomes are linked as global public health concerns. Researchers analyzed indoor and outdoor air pollution data from all inhabited continents along with key pregnancy outcomes. Their findings indicate efforts to reduce PM2.5 exposure could lead to significant reductions in the number of low-birth weight and pre-term birth infants worldwide. Air pollution reduction would be especially beneficial for children born in low- and middle-income countries.

Among children in Southern California, decreases in ambient nitrogen dioxide and PM 2.5 were associated with fewer cases of asthma.

An NIEHS-funded study found that a mixture of several B vitamins may protect DNA from changes attributable to PM 2.5 air pollution.

Bronchitis symptoms declined as pollution levels dropped in the Los Angeles region.

Improving air quality may improve cognitive function and reduce dementia risk, according to supported in part by NIH and the Alzheimer's Association.

When fossil-fuel power plants close, nearby air pollution is reduced. A study found the incidence of preterm births went down within 5 kilometers of retired coal and oil-powered plant locations.

Further Reading

Stories from the Environmental Factor (NIEHS newsletter)

Printable Fact Sheets

Podcasts

Additional Resources

Air Pollution Linked to Dementia Cases (September 2023) - In this edition of NIH Research Matters, read about findings from the Health and Retirement Study, funded by the National Institute on Aging, that showed higher air pollution exposure was linked to an increased risk of dementia. After consideration of all sources, fine particulate matter, or PM2.5, from agriculture and wildfires were specifically associated with an increased risk of dementia. Reducing such exposures might help lower the incidence of dementia. The study was published in JAMA Internal Medicine.

, a tool developed in partnership by several government agencies, allows you to monitor air quality in real time anywhere in the U.S. Simply enter your zip code as indicated on the website.

EPA's Air Sensor Toolbox provides information on the operation and use of air-sensor monitoring systems for technology developers, air-quality managers, citizen scientists, and the public.

NIH Climate Change and Health Initiative - This solutions-focused research initiative aims to reduce the health consequences associated with extreme weather events and evolving climate conditions. NIH has a strong history of creating innovative tools, technologies, and data-driven solutions to address global environmental problems.

Smoke-ready Toolbox for Wildfires is a compendium of resources from the EPA to help educate you about the risks of smoke exposure and actions that protect your health.

Wildfire Smoke Collection - The journal Environmental Health Perspectives has published high-impact papers and reviews exploring exposure and resulting health effects related to wildfires.

Related Health Topics

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Air pollution is a familiar environmental health hazard. We know what we're looking at when brown haze settles over a city, exhaust billows across a busy highway, or a plume rises from a smokestack. Some air pollution is not seen, but its pungent smell alerts you.

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GovHK (www.gov.hk. (2022, June 30). GovHK: Air Quality in Hong Kong. Www.gov.hk. https://www.gov.hk/en/residents/environment/air/airquality.htm‌

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GovHK (www.gov.hk. (2022, June 30). GovHK: Air Quality in Hong Kong. Www.gov.hk. https://www.gov.hk/en/residents/environment/air/airquality.htm‌

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Bangkok's traffic is really bad, making them under a layer of pollution. In 2020, hundreds of schools were forced to close as the particle, PM2.5, has reached a hazardous level.Bangkok has acted upon this matter to minimise both air pollution and carbon emissions. The Green Bangkok 2030 project, launched in 2019, aims to increase the ratio of green space in the city to 10sqm per person, and plant trees so that at least 30%of Bangkok's land is covered in trees.

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With approximately 26 million people living in Seoul, Air pollution is not really surprising. Discovered by the Organisation of Economic Cooperation and Development, it was discovered that Seoul had the largest amount of the toxic particle known as PM2.5 than any other state. Seoul has implemented that they would ban diesel cars from all public sector and mass transit fleets by 2025.

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Air pollution can affect people in many ways, other than just health problems. It can be harder to breathe, making people not want to go outside, and possibly even need to wear a mask to go out of their house. People such as elderly people, pregnant women, and small children are particularly vulnerable to the dangers of air pollution.

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It is possible for young, healthy adults to be affected by poor air quality, a result of irritation of the eyes, nose, and throat, coughing, tightness of the chest, and shortness of breath can occur.

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If a city's air quality is bad, it can affect people living in the city very significantly, and increase the chances of having heart disease or lung cancer. It can also inflict long-term damage to our lungs

Every hour, the Environmental Protection Department sends out an Air Quality Health Index which informs people about the condition of the air pollution and can help people with health problems know when it is safe to go outside.

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Air quality is a major concern in Hong Kong, and the Government is undertaking a number of initiatives to improve it. The following provides an overview of the problems and the solutions that are being put forward.

Air Pollution

Hong Kong's air pollution is mainly contributed by motor vehicles, marine vessels and power plants. The two greatest challenges are local street-level pollution and regional smog. Diesel vehicles, particularly trucks, buses and light buses, are the main source of street-level pollution. Smog is caused by a combination of pollutants mainly from motor vehicles, industry and power plants in Hong Kong and the Pearl River Delta. The Government released the first Clean Air Plan for Hong Kong in March 2013 which sets out in detail the various measures to tackle air pollution from power plants, land and sea transport, and non-road mobile machinery and to strengthen collaboration with Guangdong to deal with regional pollution. A progress report was published in June 2017 which gave an account on its implementation and achievements. The Government announced the Clean Air Plan for Hong Kong 2035 in June 2021 setting out the long-term goals and strategies to further enhance the air quality with a view to leading Hong Kong to become a liveable city with air quality on par with major international cities by 2035.

In March 2021, the Government announced the first Hong Kong Roadmap on the Popularisation of Electric Vehicles, setting out the long-term policy objectives and plans to promote the adoption of electric vehicles and their associated supporting facilities in Hong Kong.
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The implementation of a comprehensive vehicle emission control programme has brought along substantive air quality improvement. As of 2020, the roadside levels of nitrogen dioxide, respirable suspended particulates, fine suspended particulates and sulphur dioxide have reduced by 40%, 48%, 47% and 50% respectively compared with 2010.

With regard to improving regional air quality, the Government has long been collaborating with the Guangdong Provincial Government to implement a wide range of measures and set jointly a number of 5-year emission reduction targets. Both sides have commenced a study on "Post-2020 regional air pollutant emission reduction targets and concentration levels" with a view to formulating emission reduction strategies and targets for 2025 and 2030.

Hong Kong's Air Quality Objectives

The Government has set out Hong Kong's Air Quality Objectives (AQOs) in the Air Pollution Control Ordinance (Cap. 311), and is required to review the AQOs at least once every five years to continuously improve air quality and safeguard public health. The current AQOs took effect from 1 January 2022. The Government has embarked on a new round of review to assess the scope for further tightening the AQOs, with an aim of completing the review by 2023.
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Air Quality Health Index

The Environmental Protection Department releases hourly Air Quality Health Index (AQHI) to inform the public of the short-term health risk of air pollution in Hong Kong and helps the public take precautionary measures to protect their health. The AQHIs are reported on a scale of 1 to 10 and 10+ and are grouped into five AQHI health risk categories with health advice provided. This is particularly useful for people who are sensitive to air pollution like children, the elderly and those with heart or respiratory illnesses who need to take precautions when the health risk levels are high. The health risk categories forecast also advises the public before the onset of high health risk categories due to pollution episodes.
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Pearl River Delta Air Quality

Cooperation between the governments of Hong Kong and Guangdong is working to ensure that regional pollution levels are brought under control. At the forefront of such efforts is the Regional Air Quality Management Plan, which is coordinating individual initiatives in different cities to ensure that everyone in the Delta benefits. The Guangdong-Hong Kong-Macao Pearl River Delta Regional Air Monitoring Network is monitoring the results, which can provide you with information about the level of air pollution in the region.
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Indoor Air Quality (IAQ)

The Government's concern about air quality in Hong Kong also extends indoors. It is important to achieve and maintain a better IAQ as we spend the majority of our time indoors, either at homes, offices or on public transportation facilities. Good IAQ safeguards our health and would also help enhance Hong Kong's competitiveness over other cities.
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What You Can Do

There are a number of practical and easy ways that you can help to improve air quality both indoors and outdoors. For example, you can choose public instead of private transport and switch off domestic appliances and electric lights when they are not in use. Industry, developers and others can also play their parts by observing air pollution control laws and exercising good practices in their operations. What we do now will determine how well we live tomorrow.
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Air quality is a major concern in Hong Kong, and the Government is undertaking a number of initiatives to improve it. The following provides an overview of the problems and the solutions that are being put forward. Hong Kong's air pollution is mainly contributed by motor vehicles, marine vessels and power plants.

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Air pollution is one of the most serious problems in Hong Kong. Since Hong Kong is a busy city, there are a lot of reasons:

Firstly, there are a lot of roads, tunnels and highways for transport to go around. About 10.6 million passengers use public transport and roughly 6 hundred thousand people are using private cars in Hong Kong. About 489 gallons of gas are used for 1 car per year. That can create a serious amount of smoke and other types of gas.

Another reason is fuel oils and natural gas to heat homes, by-products of manufacturing and power generation. When fuel oils are burned, the vapours given off when gasoline evaporates and the substances produced when gasoline is burned (carbon monoxide, nitrogen oxides, particulate matter, and unburned hydrocarbons). Moreover, natural gas emits nitrogen oxides and volatile organic compounds. These problems can contribute to air pollution. In 2021, the world produced around 8 billion tonnes of coal, 4 billion tonnes of oil, and over 4 trillion cubic meters of natural gas. Most of the coal is used to generate electricity for our homes and offices and has a key role in steel production.

Finally, fumes from chemical products. There are a lot of products made from chemicals, for example, charcoal. The process of making charcoal includes strongly heating wood or other materials in minimal oxygen to remove all water and volatile constituents. During this process, a lot of fume is produced. Humans breathing the fume is very dangerous; At low concentrations can cause dizziness, nausea, headaches and stomach pains, leading to unconsciousness and paralysis. Inhaling high concentrations can rapidly lead to death.