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Light Pollution - International Dark-Sky Association

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“The sun, the moon and the stars would have disappeared long ago . . . had they happened to be within the reach of predatory human hands.” — Havelock Ellis, The Dance of Life, 1923 […]

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Chose this because it is informative and provides background info about air pollution and how dangerous it is to the environment

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this article shows the importance of pollution control in the world

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Pollution is the introduction of harmful materials into the environment. These harmful materials are called pollutants. Pollutants can be natural, such as volcanic ash. They can also be created by human activity, such as trash or runoff produced by factories. Pollutants damage the quality of air, water, and land.

Many things that are useful to people produce pollution. Cars spew pollutants from their exhaust pipes. Burning coal to create electricity pollutes the air. Industries and homes generate garbage and sewage that can pollute the land and water. Pesticides-chemical poisons used to kill weeds and insects-seep into waterways and harm wildlife.

All living things-from one-celled microbes to blue whales-depend on Earth's supply of air and water. When these resources are polluted, all forms of life are threatened.

Pollution is a global problem. Although urban areas are usually more polluted than the countryside, pollution can spread to remote places where no people live. For example, pesticides and other chemicals have been found in the Antarctic ice sheet. In the middle of the northern Pacific Ocean, a huge collection of microscopic plastic particles forms what is known as the Great Pacific Garbage Patch.

Air and water currents carry pollution. Ocean currents and migrating fish carry marine pollutants far and wide. Winds can pick up radioactive material accidentally released from a nuclear reactor and scatter it around the world. Smoke from a factory in one country drifts into another country.

In the past, visitors to Big Bend National Park in the U.S. state of Texas could see 290 kilometers (180 miles) across the vast landscape. Now, coal-burning power plants in Texas and the neighboring state of Chihuahua, Mexico have spewed so much pollution into the air that visitors to Big Bend can sometimes see only 50 kilometers (30 miles).

The three major types of pollution are air pollution, water pollution, and land pollution.

Air Pollution
Sometimes, air pollution is visible. A person can see dark smoke pour from the exhaust pipes of large trucks or factories, for example. More often, however, air pollution is invisible.

Polluted air can be dangerous, even if the pollutants are invisible. It can make people's eyes burn and make them have difficulty breathing. It can also increase the risk of lung cancer.

Sometimes, air pollution kills quickly. In 1984, an accident at a pesticide plant in Bhopal, India, released a deadly gas into the air. At least 8,000 people died within days. Hundreds of thousands more were permanently injured.

Natural disasters can also cause air pollution to increase quickly. When volcanoes erupt, they eject volcanic ash and gases into the atmosphere. Volcanic ash can discolor the sky for months. After the eruption of the Indonesian volcano of Krakatoa in 1883, ash darkened the sky around the world. The dimmer sky caused fewer crops to be harvested as far away as Europe and North America. For years, meteorologists tracked what was known as the "equatorial smoke stream." In fact, this smoke stream was a jet stream, a wind high in Earth's atmosphere that Krakatoa's air pollution made visible.

Volcanic gases, such as sulfur dioxide, can kill nearby residents and make the soil infertile for years. Mount Vesuvius, a volcano in Italy, famously erupted in 79, killing hundreds of residents of the nearby towns of Pompeii and Herculaneum. Most victims of Vesuvius were not killed by lava or landslides caused by the eruption. They were choked, or asphyxiated, by deadly volcanic gases.

In 1986, a toxic cloud developed over Lake Nyos, Cameroon. Lake Nyos sits in the crater of a volcano. Though the volcano did not erupt, it did eject volcanic gases into the lake. The heated gases passed through the water of the lake and collected as a cloud that descended the slopes of the volcano and into nearby valleys. As the toxic cloud moved across the landscape, it killed birds and other organisms in their natural habitat. This air pollution also killed thousands of cattle and as many as 1,700 people.

Most air pollution is not natural, however. It comes from burning fossil fuels-coal, oil, and natural gas. When gasoline is burned to power cars and trucks, it produces carbon monoxide, a colorless, odorless gas. The gas is harmful in high concentrations, or amounts. City traffic produces highly concentrated carbon monoxide.

Cars and factories produce other common pollutants, including nitrogen oxide, sulfur dioxide, and hydrocarbons. These chemicals react with sunlight to produce smog, a thick fog or haze of air pollution. The smog is so thick in Linfen, China, that people can seldom see the sun. Smog can be brown or grayish blue, depending on which pollutants are in it.

Smog makes breathing difficult, especially for children and older adults. Some cities that suffer from extreme smog issue air pollution warnings. The government of Hong Kong, for example, will warn people not to go outside or engage in strenuous physical activity (such as running or swimming) when smog is very thick.

When air pollutants such as nitrogen oxide and sulfur dioxide mix with moisture, they change into acids. They then fall back to earth as acid rain. Wind often carries acid rain far from the pollution source. Pollutants produced by factories and power plants in Spain can fall as acid rain in Norway.

Acid rain can kill all the trees in a forest. It can also devastate lakes, streams, and other waterways. When lakes become acidic, fish can't survive. In Sweden, acid rain created thousands of "dead lakes," where fish no longer live.

Acid rain also wears away marble and other kinds of stone. It has erased the words on gravestones and damaged many historic buildings and monuments. The Taj Mahal, in Agra, India, was once gleaming white. Years of exposure to acid rain has left it pale.

Governments have tried to prevent acid rain by limiting the amount of pollutants released into the air. In Europe and North America, they have had some success, but acid rain remains a major problem in the developing world, especially Asia.

Greenhouse gases are another source of air pollution. Greenhouse gases such as carbon dioxide and methane occur naturally in the atmosphere. In fact, they are necessary for life on Earth. They absorb sunlight reflected from Earth, preventing it from escaping into space. By trapping heat in the atmosphere, they keep Earth warm enough for people to live. This is called the greenhouse effect.

But human activities such as burning fossil fuels and destroying forests have increased the amount of greenhouse gases in the atmosphere. This has increased the greenhouse effect, and average temperatures across the globe are rising. The decade that began in the year 2000 was the warmest on record. This increase in worldwide average temperatures, caused in part by human activity, is called global warming.

Global warming is causing ice sheets and glaciers to melt. The melting ice is causing sea levels to rise at a rate of two millimeters (0.09 inches) per year. The rising seas will eventually flood low-lying coastal regions. Entire nations, such as the islands of Maldives, are threatened by this climate change.

Global warming also contributes to the phenomenon of ocean acidification. Ocean acidification is the process of ocean waters absorbing more carbon dioxide from the atmosphere. Fewer organisms can survive in warmer, less salty waters. The ocean food web is threatened as plants and animals such as coral fail to adapt to more acidic oceans.

Scientists have predicted that global warming will cause an increase in severe storms. It will also cause more droughts in some regions and more flooding in others.

The change in average temperatures is already shrinking some habitats, the regions where plants and animals naturally live. Polar bears hunt seals from sea ice in the Arctic. The melting ice is forcing polar bears to travel farther to find food, and their numbers are shrinking.

People and governments can respond quickly and effectively to reduce air pollution. Chemicals called chlorofluorocarbons (CFCs) are a dangerous form of air pollution that governments worked to reduce in the 1980s and 1990s. CFCs are found in gases that cool refrigerators, in foam products, and in aerosol cans.

CFCs damage the ozone layer, a region in Earth's upper atmosphere. The ozone layer protects Earth by absorbing much of the sun's harmful ultraviolet radiation. When people are exposed to more ultraviolet radiation, they are more likely to develop skin cancer, eye diseases, and other illnesses.

In the 1980s, scientists noticed that the ozone layer over Antarctica was thinning. This is often called the "ozone hole." No one lives permanently in Antarctica. But Australia, the home of more than 22 million people, lies at the edge of the hole. In the 1990s, the Australian government began an effort to warn people of the dangers of too much sun. Many countries, including the United States, now severely limit the production of CFCs.

Water Pollution
Some polluted water looks muddy, smells bad, and has garbage floating in it. Some polluted water looks clean, but is filled with harmful chemicals you can't see or smell.

Polluted water is unsafe for drinking and swimming. Some people who drink polluted water are exposed to hazardous chemicals that may make them sick years later. Others consume bacteria and other tiny aquatic organisms that cause disease. The United Nations estimates that 4,000 children die every day from drinking dirty water.

Sometimes, polluted water harms people indirectly. They get sick because the fish that live in polluted water are unsafe to eat. They have too many pollutants in their flesh.

There are some natural sources of water pollution. Oil and natural gas, for example, can leak into oceans and lakes from natural underground sources. These sites are called petroleum seeps. The world's largest petroleum seep is the Coal Oil Point Seep, off the coast of the U.S. state of California. The Coal Oil Point Seep releases so much oil that tar balls wash up on nearby beaches. Tar balls are small, sticky pieces of pollution that eventually decompose in the ocean.

Human activity also contributes to water pollution. Chemicals and oils from factories are sometimes dumped or seep into waterways. These chemicals are called runoff. Chemicals in runoff can create a toxic environment for aquatic life. Runoff can also help create a fertile environment for cyanobacteria, also called blue-green algae. Cyanobacteria reproduce rapidly, creating a harmful algal bloom (HAB). Harmful algal blooms prevent organisms such as plants and fish from living in the ocean. They are associated with "dead zones" in the world's lakes and rivers, places where little life exists below surface water.

Mining and drilling can also contribute to water pollution. Acid mine drainage (AMD) is a major contributor to pollution of rivers and streams near coal mines. Acid helps miners remove coal from the surrounding rocks. The acid is washed into streams and rivers, where it reacts with rocks and sand. It releases chemical sulfur from the rocks and sand, creating a river rich in sulfuric acid. Sulfuric acid is toxic to plants, fish, and other aquatic organisms. Sulfuric acid is also toxic to people, making rivers polluted by AMD dangerous sources of water for drinking and hygiene.

Oil spills are another source of water pollution. In April 2010, the Deepwater Horizon oil rig exploded in the Gulf of Mexico, causing oil to gush from the ocean floor. In the following months, hundreds of millions of gallons of oil spewed into the gulf waters. The spill produced large plumes of oil under the sea and an oil slick on the surface as large as 24,000 square kilometers (9,100 square miles). The oil slick coated wetlands in the U.S. states of Louisiana and Mississippi, killing marsh plants and aquatic organisms such as crabs and fish. Birds, such as pelicans, became coated in oil and were unable to fly or access food. More than two million animals died as a result of the Deepwater Horizon oil spill.

Buried chemical waste can also pollute water supplies. For many years, people disposed of chemical wastes carelessly, not realizing its dangers. In the 1970s, people living in the Love Canal area in Niagara Falls, New York, suffered from extremely high rates of cancer and birth defects. It was discovered that a chemical waste dump had poisoned the area's water. In 1978, 800 families living in Love Canal had to abandon their homes.

If not disposed of properly, radioactive waste from nuclear power plants can escape into the environment. Radioactive waste can harm living things and pollute the water.

Sewage that has not been properly treated is a common source of water pollution. Many cities around the world have poor sewage systems and sewage treatment plants. Delhi, the capital of India, is home to more than 21 million people. More than half the sewage and other waste produced in the city are dumped into the Yamuna River. This pollution makes the river dangerous to use as a source of water for drinking or hygiene. It also reduces the river's fishery, resulting in less food for the local community.

A major source of water pollution is fertilizer used in agriculture. Fertilizer is material added to soil to make plants grow larger and faster. Fertilizers usually contain large amounts of the elements nitrogen and phosphorus, which help plants grow. Rainwater washes fertilizer into streams and lakes. There, the nitrogen and phosphorus cause cyanobacteria to form harmful algal blooms.

Rain washes other pollutants into streams and lakes. It picks up animal waste from cattle ranches. Cars drip oil onto the street, and rain carries it into storm drains, which lead to waterways such as rivers and seas. Rain sometimes washes chemical pesticides off of plants and into streams. Pesticides can also seep into groundwater, the water beneath the surface of the Earth.

Heat can pollute water. Power plants, for example, produce a huge amount of heat. Power plants are often located on rivers so they can use the water as a coolant. Cool water circulates through the plant, absorbing heat. The heated water is then returned to the river. Aquatic creatures are sensitive to changes in temperature. Some fish, for example, can only live in cold water. Warmer river temperatures prevent fish eggs from hatching. Warmer river water also contributes to harmful algal blooms.

Another type of water pollution is simple garbage. The Citarum River in Indonesia, for example, has so much garbage floating in it that you cannot see the water. Floating trash makes the river difficult to fish in. Aquatic animals such as fish and turtles mistake trash, such as plastic bags, for food. Plastic bags and twine can kill many ocean creatures. Chemical pollutants in trash can also pollute the water, making it toxic for fish and people who use the river as a source of drinking water. The fish that are caught in a polluted river often have high levels of chemical toxins in their flesh. People absorb these toxins as they eat the fish.

Garbage also fouls the ocean. Many plastic bottles and other pieces of trash are thrown overboard from boats. The wind blows trash out to sea. Ocean currents carry plastics and other floating trash to certain places on the globe, where it cannot escape. The largest of these areas, called the Great Pacific Garbage Patch, is in a remote part of the Pacific Ocean. According to some estimates, this garbage patch is the size of Texas. The trash is a threat to fish and seabirds, which mistake the plastic for food. Many of the plastics are covered with chemical pollutants.

Land Pollution
Many of the same pollutants that foul the water also harm the land. Mining sometimes leaves the soil contaminated with dangerous chemicals.

Pesticides and fertilizers from agricultural fields are blown by the wind. They can harm plants, animals, and sometimes people. Some fruits and vegetables absorb the pesticides that help them grow. When people consume the fruits and vegetables, the pesticides enter their bodies. Some pesticides can cause cancer and other diseases.

A pesticide called DDT (dichlorodiphenyltrichloroethane) was once commonly used to kill insects, especially mosquitoes. In many parts of the world, mosquitoes carry a disease called malaria, which kills a million people every year. Swiss chemist Paul Hermann Muller was awarded the Nobel Prize for his understanding of how DDT can control insects and other pests. DDT is responsible for reducing malaria in places such as Taiwan and Sri Lanka.

In 1962, American biologist Rachel Carson wrote a book called combat malaria.

Trash is another form of land pollution. Around the world, paper, cans, glass jars, plastic products, and junked cars and appliances mar the landscape. Litter makes it difficult for plants and other producers in the food web to create nutrients. Animals can die if they mistakenly eat plastic.

Garbage often contains dangerous pollutants such as oils, chemicals, and ink. These pollutants can leech into the soil and harm plants, animals, and people.

Inefficient garbage collection systems contribute to land pollution. Often, the garbage is picked up and brought to a dump, or landfill. Garbage is buried in landfills. Sometimes, communities produce so much garbage that their landfills are filling up. They are running out of places to dump their trash.

A massive landfill near Quezon City, Philippines, was the site of a land pollution tragedy in 2000. Hundreds of people lived on the slopes of the Quezon City landfill. These people made their living from recycling and selling items found in the landfill. However, the landfill was not secure. Heavy rains caused a trash landslide, killing 218 people.

Sometimes, landfills are not completely sealed off from the land around them. Pollutants from the landfill leak into the earth in which they are buried. Plants that grow in the earth may be contaminated, and the herbivores that eat the plants also become contaminated. So do the predators that consume the herbivores. This process, where a chemical builds up in each level of the food web, is called bioaccumulation.

Pollutants leaked from landfills also leak into local groundwater supplies. There, the aquatic food web (from microscopic algae to fish to predators such as sharks or eagles) can suffer from bioaccumulation of toxic chemicals.

Some communities do not have adequate garbage collection systems, and trash lines the side of roads. In other places, garbage washes up on beaches. Kamilo Beach, in the U.S. state of Hawai'i, is littered with plastic bags and bottles carried in by the tide. The trash is dangerous to ocean life and reduces economic activity in the area. Tourism is Hawai'i's largest industry. Polluted beaches discourage tourists from investing in the area's hotels, restaurants, and recreational activities.

Some cities incinerate, or burn, their garbage. Incinerating trash gets rid of it, but it can release dangerous heavy metals and chemicals into the air. So while trash incinerators can help with the problem of land pollution, they sometimes add to the problem of air pollution.

Reducing Pollution
Around the world, people and governments are making efforts to combat pollution. Recycling, for instance, is becoming more common. In recycling, trash is processed so its useful materials can be used again. Glass, Silent Spring, which discussed the dangers of DDT. She argued that it could contribute to cancer in humans. She also explained how it was destroying bird eggs, which caused the number of bald eagles, brown pelicans, and ospreys to drop. In 1972, the United States banned the use of DDT. Many other countries also banned it. But DDT didn't disappear entirely. Today, many governments support the use of DDT because it remains the most effective way to aluminum cans, and many types of plastic can be melted and reused. Paper can be broken down and turned into new paper.

Recycling reduces the amount of garbage that ends up in landfills, incinerators, and waterways. Austria and Switzerland have the highest recycling rates. These nations recycle between 50 and 60 percent of their garbage. The United States recycles about 30 percent of its garbage.

Governments can combat pollution by passing laws that limit the amount and types of chemicals factories and agribusinesses are allowed to use. The smoke from coal-burning power plants can be filtered. People and businesses that illegally dump pollutants into the land, water, and air can be fined for millions of dollars. Some government programs, such as the Superfund program in the United States, can force polluters to clean up the sites they polluted.

International agreements can also reduce pollution. The Kyoto Protocol, a United Nations agreement to limit the emission of greenhouse gases, has been signed by 191 countries. The United States, the world's second-largest producer of greenhouse gases, did not sign the agreement. Other countries, such as China, the world's largest producer of greenhouse gases, have not met their goals.

Still, many gains have been made. In 1969, the Cuyahoga River, in the U.S. state of Ohio, was so clogged with oil and trash that it caught on fire. The fire helped spur the Clean Water Act of 1972. This law limited what pollutants could be released into water and set standards for how clean water should be. Today, the Cuyahoga River is much cleaner. Fish have returned to regions of the river where they once could not survive.

But even as some rivers are becoming cleaner, others are becoming more polluted. As countries around the world become wealthier, some forms of pollution increase. Countries with growing economies usually need more power plants, which produce more pollutants.

Reducing pollution requires environmental, political, and economic leadership. Developed nations must work to reduce and recycle their materials, while developing nations must work to strengthen their economies without destroying the environment. Developed and developing countries must work together toward the common goal of protecting the environment for future use.

Fast Fact

How Long Does It Last?
Different materials decompose at different rates. How long does it take for these common types of trash to break down?

Fast Fact

Indoor Air Pollution
The air inside your house can be polluted. Air and carpet cleaners, insect sprays, and cigarettes are all sources of indoor air pollution.

Fast Fact

Light Pollution
Light pollution is the excess amount of light in the night sky. Light pollution, also called photopollution, is almost always found in urban areas. Light pollution can disrupt ecosystems by confusing the distinction between night and day. Nocturnal animals, those that are active at night, may venture out during the day, while diurnal animals, which are active during daylight hours, may remain active well into the night. Feeding and sleep patterns may be confused. Light pollution also indicates an excess use of energy.

The dark-sky movement is a campaign by people to reduce light pollution. This would reduce energy use, allow ecosystems to function more normally, and allow scientists and stargazers to observe the atmosphere.

Fast Fact

Noise Pollution
Noise pollution is the constant presence of loud, disruptive noises in an area. Usually, noise pollution is caused by construction or nearby transportation facilities, such as airports.

Noise pollution is unpleasant, and can be dangerous. Some songbirds, such as robins, are unable to communicate or find food in the presence of heavy noise pollution. The sound waves produced by some noise pollutants can disrupt the sonar used by marine animals to communicate or locate food.

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Illustrators

Mary Crooks, National Geographic Society

Editors

Jeannie Evers, Emdash Editing, Emdash Editing

Producer

National Geographic Society

other

Last Updated

October 19, 2023

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Pollution is the introduction of harmful materials into the environment. These harmful materials are called pollutants.

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this image shows how impactful plastic can be on the environment

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Water Pollution Facts: What Are The Causes And Solutions?

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Earth and everything living on it are heavily reliant on water for survival, yet we don't show the care needed to sustain it. Read about water pollution.

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8.9 million people die a year from pollution related illness.

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Here's How Many People Die from Pollution Around the World

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Air pollution and water pollution affect many countries, especially China. Find out how many air pollution deaths occur around the world.

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Air pollution can also affect humans and their breathing

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WHO: Breathe Life - How air pollution impacts your body

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Air pollution is affecting China and the residents.

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China is choking on its own success. The economy is on a historic run, posting a succession of double-digit growth rates. But the growth derives, now more than at any time in the recent past, from a staggering expansion of heavy industry and urbanization that requires colossal inputs of energy, almost all from coal, the most readily available, and dirtiest, source.

"It is a very awkward situation for the country because our greatest achievement is also our biggest burden," says Wang Jinnan, one of China's leading environmental researchers. "There is pressure for change, but many people refuse to accept that we need a new approach so soon."

China's problem has become the world's problem. Sulfur dioxide and nitrogen oxides spewed by China's coal-fired power plants fall as acid rain on Seoul, South Korea, and Tokyo. Much of the particulate pollution over Los Angeles originates in China, according to the Journal of Geophysical Research.

More pressing still, China has entered the most robust stage of its industrial revolution, even as much of the outside world has become preoccupied with global warming.

Experts once thought China might overtake the United States as the world's leading producer of greenhouse gases by 2010, possibly later. Now, the International Energy Agency has said China could become the emissions leader by the end of this year, and the Netherlands Environment Assessment Agency said China had already passed that level.

For the Communist Party, the political calculus is daunting. Reining in economic growth to alleviate pollution may seem logical, but the country's authoritarian system is addicted to fast growth. Delivering prosperity placates the public, provides spoils for well-connected officials and forestalls demands for political change. A major slowdown could incite social unrest, alienate business interests and threaten the party's rule.

But pollution poses its own threat. Officials blame fetid air and water for thousands of episodes of social unrest. Health care costs have climbed sharply. Severe water shortages could turn more farmland into desert. And the unconstrained expansion of energy-intensive industries creates greater dependence on imported oil and dirty coal, meaning that environmental problems get harder and more expensive to address the longer they are unresolved.

China's leaders recognize that they must change course. They are vowing to overhaul the growth-first philosophy of the Deng Xiaoping era and embrace a new model that allows for steady growth while protecting the environment. In his equivalent of a State of the Union address this year, Prime Minister Wen Jiabao made 48 references to "environment," "pollution" or "environmental protection."

The government has numerical targets for reducing emissions and conserving energy. Export subsidies for polluting industries have been phased out. Different campaigns have been started to close illegal coal mines and shutter some heavily polluting factories. Major initiatives are under way to develop clean energy sources like solar and wind power. And environmental regulation in Beijing, Shanghai and other leading cities has been tightened ahead of the 2008 Olympics.

Yet most of the government's targets for energy efficiency, as well as improving air and water quality, have gone unmet. And there are ample signs that the leadership is either unwilling or unable to make fundamental changes.

Land, water, electricity, oil and bank loans remain relatively inexpensive, even for heavy polluters. Beijing has declined to use the kind of tax policies and market-oriented incentives for conservation that have worked well in Japan and many European countries.

Provincial officials, who enjoy substantial autonomy, often ignore environmental edicts, helping to reopen mines or factories closed by central authorities. Over all, enforcement is often tinged with corruption. This spring, officials in Yunnan Province in southern China beautified Laoshou Mountain, which had been used as a quarry, by spraying green paint over acres of rock.

President Hu Jintao's most ambitious attempt to change the culture of fast-growth collapsed this year. The project, known as "Green G.D.P.," was an effort to create an environmental yardstick for evaluating the performance of every official in China. It recalculated gross domestic product, or G.D.P., to reflect the cost of pollution.

But the early results were so sobering - in some provinces the pollution-adjusted growth rates were reduced almost to zero - that the project was banished to China's ivory tower this spring and stripped of official influence.

Chinese leaders argue that the outside world is a partner in degrading the country's environment. Chinese manufacturers that dump waste into rivers or pump smoke into the sky make the cheap products that fill stores in the United States and Europe. Often, these manufacturers subcontract for foreign companies - or are owned by them. In fact, foreign investment continues to rise as multinational corporations build more factories in China. Beijing also insists that it will accept no mandatory limits on its carbon dioxide emissions, which would almost certainly reduce its industrial growth. It argues that rich countries caused global warming and should find a way to solve it without impinging on China's development.

Indeed, Britain, the United States and Japan polluted their way to prosperity and worried about environmental damage only after their economies matured and their urban middle classes demanded blue skies and safe drinking water.

But China is more like a teenage smoker with emphysema. The costs of pollution have mounted well before it is ready to curtail economic development. But the price of business as usual - including the predicted effects of global warming on China itself - strikes many of its own experts and some senior officials as intolerably high.

"Typically, industrial countries deal with green problems when they are rich," said Ren Yong, a climate expert at the Center for Environment and Economy in Beijing. "We have to deal with them while we are still poor. There is no model for us to follow."

In the face of past challenges, the Communist Party has usually responded with sweeping edicts from Beijing. Some environmentalists say they hope the top leadership has now made pollution control such a high priority that lower level officials will have no choice but to go along, just as Deng Xiaoping once forced China's sluggish bureaucracy to fixate on growth.

But the environment may end up posing a different political challenge. A command-and-control political culture accustomed to issuing thundering directives is now under pressure, even from people in the ruling party, to submit to oversight from the public, for which pollution has become a daily - and increasingly deadly - reality.
Perpetual Haze
During the three decades since Deng set China on a course toward market-style growth, rapid industrialization and urbanization have lifted hundreds of millions of Chinese out of poverty and made the country the world's largest producer of consumer goods. But there is little question that growth came at the expense of the country's air, land and water, much of it already degraded by decades of Stalinist economic planning that emphasized the development of heavy industries in urban areas.

For air quality, a major culprit is coal, on which China relies for about two-thirds of its energy needs. It has abundant supplies of coal and already burns more of it than the United States, Europe and Japan combined. But even many of its newest coal-fired power plants and industrial furnaces operate inefficiently and use pollution controls considered inadequate in the West.

Expanding car ownership, heavy traffic and low-grade gasoline have made autos the leading source of air pollution in major Chinese cities. Only 1 percent of China's urban population of 560 million now breathes air considered safe by the European Union, according to a World Bank study of Chinese pollution published this year. One major pollutant contributing to China's bad air is particulate matter, which includes concentrations of fine dust, soot and aerosol particles less than 10 microns in diameter (known as PM 10).

The level of such particulates is measured in micrograms per cubic meter of air. The European Union stipulates that any reading above 40 micrograms is unsafe. The United States allows 50. In 2006, Beijing's average PM 10 level was 141, according to the Chinese National Bureau of Statistics. Only Cairo, among world capitals, had worse air quality as measured by particulates, according to the World Bank.

Emissions of sulfur dioxide from coal and fuel oil, which can cause respiratory and cardiovascular diseases as well as acid rain, are increasing even faster than China's economic growth. In 2005, China became the leading source of sulfur dioxide pollution globally, the State Environmental Protection Administration, or SEPA, reported last year.

Other major air pollutants, including ozone, an important component of smog, and smaller particulate matter, called PM 2.5, emitted when gasoline is burned, are not widely monitored in China. Medical experts in China and in the West have argued that PM 2.5 causes more chronic diseases of the lung and heart than the more widely watched PM 10.

Perhaps an even more acute challenge is water. China has only one-fifth as much water per capita as the United States. But while southern China is relatively wet, the north, home to about half of China's population, is an immense, parched region that now threatens to become the world's biggest desert.

Farmers in the north once used shovels to dig their wells. Now, many aquifers have been so depleted that some wells in Beijing and Hebei must extend more than half a mile before they reach fresh water. Industry and agriculture use nearly all of the flow of the Yellow River, before it reaches the Bohai Sea.

In response, Chinese leaders have undertaken one of the most ambitious engineering projects in world history, a $60 billion network of canals, rivers and lakes to transport water from the flood-prone Yangtze River to the silt-choked Yellow River. But that effort, if successful, will still leave the north chronically thirsty.

This scarcity has not yet created a culture of conservation. Water remains inexpensive by global standards, and Chinese industry uses 4 to 10 times more water per unit of production than the average in industrialized nations, according to the World Bank.

In many parts of China, factories and farms dump waste into surface water with few repercussions. China's environmental monitors say that one-third of all river water, and vast sections of China's great lakes, the Tai, Chao and Dianchi, have water rated Grade V, the most degraded level, rendering it unfit for industrial or agricultural use.
Grim Statistics
The toll this pollution has taken on human health remains a delicate topic in China. The leadership has banned publication of data on the subject for fear of inciting social unrest, said scholars involved in the research. But the results of some research provide alarming evidence that the environment has become one of the biggest causes of death.

An internal, unpublicized report by the Chinese Academy of Environmental Planning in 2003 estimated that 300,000 people die each year from ambient air pollution, mostly of heart disease and lung cancer. An additional 110,000 deaths could be attributed to indoor air pollution caused by poorly ventilated coal and wood stoves or toxic fumes from shoddy construction materials, said a person involved in that study.

Another report, prepared in 2005 by Chinese environmental experts, estimated that annual premature deaths attributable to outdoor air pollution were likely to reach 380,000 in 2010 and 550,000 in 2020.

This spring, a World Bank study done with SEPA, the national environmental agency, concluded that outdoor air pollution was already causing 350,000 to 400,000 premature deaths a year. Indoor pollution contributed to the deaths of an additional 300,000 people, while 60,000 died from diarrhea, bladder and stomach cancer and other diseases that can be caused by water-borne pollution.

China's environmental agency insisted that the health statistics be removed from the published version of the report, citing the possible impact on "social stability," World Bank officials said.

But other international organizations with access to Chinese data have published similar results. For example, the World Health Organization found that China suffered more deaths from water-related pollutants and fewer from bad air, but agreed with the World Bank that the total death toll had reached 750,000 a year. In comparison, 4,700 people died last year in China's notoriously unsafe mines, and 89,000 people were killed in road accidents, the highest number of automobile-related deaths in the world. The Ministry of Health estimates that cigarette smoking takes a million Chinese lives each year.

Studies of Chinese environmental health mostly use statistical models developed in the United States and Europe and apply them to China, which has done little long-term research on the matter domestically. The results are more like plausible suppositions than conclusive findings.

But Chinese experts say that, if anything, the Western models probably understate the problems.

"China's pollution is worse, the density of its population is greater and people do not protect themselves as well," said Jin Yinlong, the director general of the Institute for Environmental Health and Related Product Safety in Beijing. "So the studies are not definitive. My assumption is that they will turn out to be conservative."
Growth Run Amok
As gloomy as China's pollution picture looks today, it is set to get significantly worse, because China has come to rely mainly on energy-intensive heavy industry and urbanization to fuel economic growth. In 2000, a team of economists and energy specialists at the Development Research Center, part of the State Council, set out to gauge how much energy China would need over the ensuing 20 years to achieve the leadership's goal of quadrupling the size of the economy.

They based their projections on China's experience during the first 20 years of economic reform, from 1980 to 2000. In that period, China relied mainly on light industry and small-scale private enterprise to spur growth. It made big improvements in energy efficiency even as the economy expanded rapidly. Gross domestic product quadrupled, while energy use only doubled.

The team projected that such efficiency gains would probably continue. But the experts also offered what they called a worst-case situation in which the most energy-hungry parts of the economy grew faster and efficiency gains fell short.

That worst-case situation now looks wildly optimistic. Last year, China burned the energy equivalent of 2.7 billion tons of coal, three-quarters of what the experts had said would be the maximum required in 2020. To put it another way, China now seems likely to need as much energy in 2010 as it thought it would need in 2020 under the most pessimistic assumptions.

"No one really knew what was driving the economy, which is why the predictions were so wrong," said Yang Fuqiang, a former Chinese energy planner who is now the chief China representative of the Energy Foundation, an American group that supports energy-related research. "What I fear is that the trend is now basically irreversible."

The ravenous appetite for fossil fuels traces partly to an economic stimulus program in 1997. The leadership, worried that China's economy would fall into a steep recession as its East Asian neighbors had, provided generous state financing and tax incentives to support industrialization on a grand scale.

It worked well, possibly too well. In 1996, China and the United States each accounted for 13 percent of global steel production. By 2005, the United States share had dropped to 8 percent, while China's share had risen to 35 percent, according to a study by Daniel H. Rosen and Trevor Houser of China Strategic Advisory, a group that analyzes the Chinese economy.

Similarly, China now makes half of the world's cement and flat glass, and about a third of its aluminum. In 2006, China overtook Japan as the second-largest producer of cars and trucks after the United States.

Its energy needs are compounded because even some of its newest heavy industry plants do not operate as efficiently, or control pollution as effectively, as factories in other parts of the world, a recent World Bank report said.

Chinese steel makers, on average, use one-fifth more energy per ton than the international average. Cement manufacturers need 45 percent more power, and ethylene producers need 70 percent more than producers elsewhere, the World Bank says.

China's aluminum industry alone consumes as much energy as the country's commercial sector - all the hotels, restaurants, banks and shopping malls combined, Mr. Rosen and Mr. Houser reported.

Moreover, the boom is not limited to heavy industry. Each year for the past few years, China has built about 7.5 billion square feet of commercial and residential space, more than the combined floor space of all the malls and strip malls in the United States, according to data collected by the United States Energy Information Administration.

Chinese buildings rarely have thermal insulation. They require, on average, twice as much energy to heat and cool as those in similar climates in the United States and Europe, according to the World Bank. A vast majority of new buildings - 95 percent, the bank says - do not meet China's own codes for energy efficiency.

All these new buildings require China to build power plants, which it has been doing prodigiously. In 2005 alone, China added 66 gigawatts of electricity to its power grid, about as much power as Britain generates in a year. Last year, it added an additional 102 gigawatts, as much as France.

That increase has come almost entirely from small- and medium-size coal-fired power plants that were built quickly and inexpensively. Only a few of them use modern, combined-cycle turbines, which increase efficiency, said Noureddine Berrah, an energy expert at the World Bank. He said Beijing had so far declined to use the most advanced type of combined-cycle turbines despite having completed a successful pilot project nearly a decade ago.

While over the long term, combined-cycle plants save money and reduce pollution, Mr. Berrah said, they cost more - and take longer - to build. For that reason, he said, central and provincial government officials prefer older technology.

"China is making decisions today that will affect its energy use for the next 30 or 40 years," he said. "Unfortunately, in some parts of the government the thinking is much more shortsighted."
The Politics of Pollution
Since Hu Jintao became the Communist Party chief in 2002 and Wen Jiabao became prime minister the next spring, China's leadership has struck consistent themes. The economy must grow at a more sustainable, less bubbly pace. Environmental abuse has reached intolerable levels. Officials who ignore these principles will be called to account.

Five years later, it seems clear that these senior leaders are either too timid to enforce their orders, or the fast-growth political culture they preside over is too entrenched to heed them.

In the second quarter of this year, the economy expanded at a neck-snapping pace of 11.9 percent, its fastest in a decade. State-driven investment projects, state-backed heavy industry and a thriving export sector led the way. China burned 18 percent more coal than it did the year before.

China's authoritarian system has repeatedly proved its ability to suppress political threats to Communist Party rule. But its failure to realize its avowed goals of balancing economic growth and environmental protection is a sign that the country's environmental problems are at least partly systemic, many experts and some government officials say. China cannot go green, in other words, without political change.

In their efforts to free China of its socialist shackles in the 1980s and early 90s, Deng and his supporters gave lower-level officials the leeway, and the obligation, to increase economic growth.

Local party bosses gained broad powers over state bank lending, taxes, regulation and land use. In return, the party leadership graded them, first and foremost, on how much they expanded the economy in their domains.

To judge by its original goals - stimulating the economy, creating jobs and keeping the Communist Party in power - the system Deng put in place has few equals. But his approach eroded Beijing's ability to fine-tune the economy. Today, a culture of collusion between government and business has made all but the most pro-growth government policies hard to enforce.

"The main reason behind the continued deterioration of the environment is a mistaken view of what counts as political achievement," said Pan Yue, the deputy minister of the State Environmental Protection Administration. "The crazy expansion of high-polluting, high-energy industries has spawned special interests. Protected by local governments, some businesses treat the natural resources that belong to all the people as their own private property."

Mr. Hu has tried to change the system. In an internal address in 2004, he endorsed "comprehensive environmental and economic accounting" - otherwise known as "Green G.D.P." He said the "pioneering endeavor" would produce a new performance test for government and party officials that better reflected the leadership's environmental priorities.

The Green G.D.P. team sought to calculate the yearly damage to the environment and human health in each province. Their first report, released last year, estimated that pollution in 2004 cost just over 3 percent of the gross domestic product, meaning that the pollution-adjusted growth rate that year would drop to about 7 percent from 10 percent. Officials said at the time that their formula used low estimates of environmental damage to health and did not assess the impact on China's ecology. They would produce a more decisive formula, they said, the next year.

That did not happen. Mr. Hu's plan died amid intense squabbling, people involved in the effort said. The Green G.D.P. group's second report, originally scheduled for release in March, never materialized.

The official explanation was that the science behind the green index was immature. Wang Jinnan, the leading academic researcher on the Green G.D.P. team, said provincial leaders killed the project. "Officials do not like to be lined up and told how they are not meeting the leadership's goals," he said. "They found it difficult to accept this."
Conflicting Pressures
Despite the demise of Green G.D.P., party leaders insist that they intend to restrain runaway energy use and emissions. The government last year mandated that the country use 20 percent less energy to achieve the same level of economic activity in 2010 compared with 2005. It also required that total emissions of mercury, sulfur dioxide and other pollutants decline by 10 percent in the same period.

The program is a domestic imperative. But it has also become China's main response to growing international pressure to combat global warming. Chinese leaders reject mandatory emissions caps, and they say the energy efficiency plan will slow growth in carbon dioxide emissions.

Even with the heavy pressure, though, the efficiency goals have been hard to achieve. In the first full year since the targets were set, emissions increased. Energy use for every dollar of economic output fell but by much less than the 4 percent interim goal.

In a public relations sense, the party's commitment to conservation seems steadfast. Mr. Hu shunned his usual coat and tie at a meeting of the Central Committee this summer. State news media said the temperature in the Great Hall of the People was set at a balmy 79 degrees Fahrenheit to save energy, and officials have encouraged others to set thermostats at the same level.

By other measures, though, the leadership has moved slowly to address environmental and energy concerns.

The government rarely uses market-oriented incentives to reduce pollution. Officials have rejected proposals to introduce surcharges on electricity and coal to reflect the true cost to the environment. The state still controls the price of fuel oil, including gasoline, subsidizing the cost of driving.

Energy and environmental officials have little influence in the bureaucracy. The environmental agency still has only about 200 full-time employees, compared with 18,000 at the Environmental Protection Agency in the United States.

China has no Energy Ministry. The Energy Bureau of the National Development and Reform Commission, the country's central planning agency, has 100 full-time staff members. The Energy Department of the United States has 110,000 employees.

China does have an army of amateur regulators. Environmentalists expose pollution and press local government officials to enforce environmental laws. But private individuals and nongovernment organizations cannot cross the line between advocacy and political agitation without risking arrest.

At least two leading environmental organizers have been prosecuted in recent weeks, and several others have received sharp warnings to tone down their criticism of local officials. One reason the authorities have cited: the need for social stability before the 2008 Olympics, once viewed as an opportunity for China to improve the environment.

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China is choking on its own success. The economy is on a historic run, posting a succession of double-digit growth rates. But the growth derives, now more than at any time in the recent past, from a staggering expansion of heavy industry and urbanization that requires colossal inputs of energy, almost all from coal, the most readily available, and dirtiest, source.

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Outdoor air pollution has grown 8% globally in the past five years, with billions of people around the world now exposed to dangerous air, according to new data from more than 3,000 cities compiled by the World Health Organisation (WHO).

3,000 cities on WHO report

While all regions are affected, fast-growing cities in the Middle East, south-east Asia and the western Pacific are the most impacted with many showing pollution levels at five to 10 times above WHO recommended levels.

Bar chart of cities by region

According to the new WHO database, levels of ultra-fine particles of less than 2.5 microns (PM2.5s) are highest in India, which has 16 of the world's 30 most polluted cities.
China, which has been plagued by air pollution, has improved its air quality since 2011 and now has only five cities in the top 30. Nine other countries, including Pakistan and Iran, have one city each in the worst 30.

China and India PM 2.5

For the larger, but slightly less dangerous PM10 particles, India has eight cities in the world's top 30. Nigeria, Saudi Arabia and Pakistan each have two cities in the top 10. The true figure for the growth in global air pollution is likely to be worse because only a handful of African cities monitor their levels.

The most polluted city in the world, according to the WHO data, is Onitsha, a fast-growing port and transit city in south-eastern Nigeria that recorded levels of nearly 600 micrograms per cubic metre of PM10s - around 30 times the WHO recommended level of 20 micrograms per cubic metre.

Africa and Asia PM 10

Air pollution levels were generally much lower for cities in developed countries with Sydney, New York and London registering 17, 16 and 22 micrograms per cubic metre for PM10s respectively. However, the data only includes measurements for particulates and does not include forms of air pollution such as NO2 and ozone.

"We have a public health emergency in many countries. Urban air pollution continues to rise at an alarming rate, wreaking havoc on human health. It's dramatic, one of the biggest problems we are facing globally, with terrible future costs to society," said Dr Maria Neira, director of public health at the WHO in Geneva.
"The cost for countries is enormous. Air pollution affects economies and people's quality of life. It leads to major chronic diseases and to people ultimately dying," she said.

The new data, drawn from city and academic records, shows a rapid deterioration in air quality as low-income cities grow unchecked and populations become unable to escape clouds of smog and soot from transport, industry, construction sites, farming and wood-burning in homes.
Outdoor air pollution causes more than 3m deaths a year - more than malaria and HIV/Aids - and is now the biggest single killer in the world. The toll is expected to double as urban populations increase and car numbers approach 2bn by 2050.
Air pollutants such as sulphates, nitrates and black carbon penetrate deep into the lungs and into the cardiovascular system, posing the greatest risks to human health, says the UN.

"As urban air quality declines, the risk of stroke, heart disease, lung cancer, and chronic and acute respiratory diseases, including asthma, increases for the people who live in them. When dirty air blankets our cities the most vulnerable urban populations - the youngest, oldest and poorest - are the most impacted," said Flavia Bustreo, WHO assistant director general.

Encouragingly, there is evidence from the WHO data that many cities are addressing air pollution. More than half of the monitored cities in high-income countries and more than one-third of those in low- and middle-income countries reduced their air pollution levels by more than 5% in five years. Delhi, one of the most polluted cities in the world, has banned large diesel cars from going into the city centre.

Measures taken by cities include reducing industrial smokestack emissions, increasing the use of renewable power sources like solar and wind, and prioritising rapid transit, walking and cycling networks in cities. Many cities are also committed to reducing reducing car traffic and diesel vehicles in particular.

The UN's third outdoor air pollution database suggests the cleanest cities in the world are generally small, wealthy and situated far from industrial centres. Muonio in Finland, a town above the Arctic circle, has the world's purest recorded urban air, recording just 2 micrograms per cubic metre of PM2.5 pollution and 4 micrograms per cubic metre of PM10s. It is closely followed by Norman Wells in Canada, Campisábalos in Spain and Converse County, Wyoming in the US.

Search database

Of 52 UK towns and cities included in the UN database, Port Talbot in south Wales, a hub for the UK steel industry, is the most polluted, ahead of London, Glasgow, Southampton and Leeds. The cleanest UK city in the WHO list is Inverness, followed by Bournemouth, Newcastle and Sunderland.

The most polluted city in Australia, according to the data, is Geraldton, a major seaport on the west coast, north of Perth. The most polluted city in the United States is the inland city of Visalia-Porterville in California.
Eastbourne a surprise name among UK's most polluted towns and cities
"More than 80% of people living in urban areas that monitor air pollution are exposed to air quality levels that exceed the World Health Organisation limits. While all regions of the world are affected, populations in low-income cities are the most impacted; 98% of cities in low- and middle income countries with more than 100,000 inhabitants do not meet WHO air quality guidelines. However, in high income countries, that percentage decreases to 56%," said the WHO.

"It is crucial for city and national governments to make urban air quality a health and development priority," said Dr Carlos Dora, co-ordinator of the WHO's Interventions for Healthy Environment programme. "When air quality improves, health costs from air pollution related diseases shrink, worker productivity expands and life expectancy grows. Reducing air pollution also brings an added climate bonus, which can become a part of countries' commitments to the climate treaty."
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Air pollution rising at an 'alarming rate' in world's cities

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Outdoor air pollution has grown 8% globally in the past five years, with billions of people around the world now exposed to dangerous air, according to new data from more than 3,000 cities compiled by the World Health Organisation (WHO).