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How does the ozone affect the environment? A.B.C

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How does the ozone affect the environment? A.B.C

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"Ozone damages vegetation and ecosystems by inhibiting the ability of plants to open the microscopic pores on their leaves to breathe. It messes up photosynthesis by not letting the plant get enough carbon dioxide to process and turn into oxygen."

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Human Health Effects

Ozone can inflame the lung's lining. These photos show a healthy lung air way (left) and an inflamed lung air way (right). Photos courtesy of EPA.

Breathing ground-level ozone can trigger a variety of health problems including chest pain, coughing, throat irritation, and congestion. It can worsen bronchitis, emphysema, and asthma. Ozone also can reduce lung function and inflame the lining of the lungs. Repeated exposure may permanently scar lung tissue.

Healthy people also experience difficulty breathing when exposed to ozone pollution. Because ozone forms in hot weather, anyone who spends time outdoors in the summer may be affected, particularly children, outdoor workers and people exercising. Some people who don't fall into any of these categories may also find themselves sensitive to ozone.

For detailed information about how ozone affects human health, go to EPA's "Health Effects of Ozone in the General Population" web page.

Ozone can reduce lung function, making it more difficult to breathe deeply and quickly. Those with lung diseases, children, outdoor workers, and those who exercise outdoors should reduce activity levels or stay indoors when ozone levels are elevated.

Environmental Effects

Signs of ozone damage include flecking, stippling, bronzing and reddening on plant leaves. Photo courtesy of USDA

Ozone damages vegetation and ecosystems by inhibiting the ability of plants to open the microscopic pores on their leaves to breathe. It interferes with the photosynthesis process by reducing the amount of carbon dioxide the plants can process and release as oxygen.

Elevated levels of ozone leads to reduced agricultural crop and commercial forest yields, reduced growth and survivability of tree seedlings, and increased susceptibility to diseases, pests and other stresses such as harsh weather.

Yield Loss Caused by Ozone

Dicot species, such a soybean, cotton and peanut, are more sensitive to yield loss caused by ozone than monocot species such as sorghum, field corn and winter wheat. The USDA provides additional information on the effects of ozone air pollution on plants.

Heagle, AS. 1989. Ozone and crop yield. Annual Review of Phytopathology 27:397-423.

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Breathing ground-level ozone can trigger a variety of human health effects including chest pain, coughing, throat irritation, and congestion.

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"The ozone and Climate change are both linked in a number of ways that make climate change happen. Atmospheric ozone has two effects on the temperature balance of the Earth. It absorbs solar ultraviolet radiation, which heats the stratosphere."

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Frequently Asked Questions About Ozone

9. Does Ozone Depletion Cause Climate Change?

Ozone depletion and climate change are linked in a number of ways, but ozone depletion is not a major cause of climate change.

Atmospheric ozone has two effects on the temperature balance of the Earth. It absorbs solar ultraviolet radiation, which heats the stratosphere. It also absorbs infrared radiation emitted by the Earth's surface, effectively trapping heat in the troposphere. Therefore, the climate impact of changes in ozone concentrations varies with the altitude at which these ozone changes occur. The major ozone losses that have been observed in the lower stratosphere due to the human-produced chlorine- and bromine-containing gases have a cooling effect on the Earth's surface. On the other hand, the ozone increases that are estimated to have occurred in the troposphere because of surface-pollution gases have a warming effect on the Earth's surface, thereby contributing to the "greenhouse" effect.

In comparison to the effects of changes in other atmospheric gases, the effects of both of these ozone changes are difficult to calculate accurately. In the figure below, the upper ranges of possible effects from the ozone changes are indicated by the open bars, and the lower ranges are indicated by the solid bars.

As shown in the figure, the increase in carbon dioxide is the major contributor to climate change. Carbon dioxide concentrations are increasing in the atmosphere primarily as the result of the burning of coal, oil, and natural gas for energy and transportation. The atmospheric abundance of carbon dioxide is currently about 30% above what it was 150 years ago. The relative impacts on climate of various other "greenhouse" gases are also shown on the figure.

There is an additional factor that indirectly links ozone depletion to climate change; namely, many of the same gases that are causing ozone depletion are also contributing to climate change. These gases, such as the chlorofluorocarbons (CFCs), are greenhouse gases, absorbing some of the infrared radiation emitted by the Earth's surface, thereby effectively heating the Earth's surface.

Conversely, changes in the climate of the Earth could affect the behavior of the ozone layer, because ozone is influenced by changes in the meteorological conditions and by changes in the atmospheric composition that could result from climate change. The major issue is that the stratosphere will most probably cool in response to climate change, therefore preserving over a longer time period the conditions that promote chlorine-caused ozone depletion in the lower stratosphere, particularly in polar regions. At present, the amplitude and extent of such a cooling, and therefore the delay in the recovery of the ozone layer, still have to be assessed.

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national oceanic and atmospheric administration

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Scientific Assessment of Ozone Depletion: 1998

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Ozone depletion and climate change are linked in a number of ways, but ozone depletion is not a major cause of climate change. Atmospheric ozone has two effects on the temperature balance of the Earth. It absorbs solar ultraviolet radiation, which heats the stratosphere.

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"The ozone layer is made out of natural gas in the atmosphere that's protects all living things from harmful ultraviolet from the sun."

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The EU 'Ozone Regulation' - Regulation (EC) 1005/2009 on substances that deplete the ozone layer - provides the legal basis for the protection of the...

Licences & reporting for uses in the EUThe import and export of ozone-depleting substances (ODS), as well as their production for laboratory and...

World governments agreed in the late 1980s to protect the Earth's ozone layer by phasing out ozone-depleting substances emitted by human activities, under the Montreal Protocol. In Europe, the Protocol is implemented through EU-wide legislation that not only meets its objectives but also contains stricter, more ambitious measures.

Global action taken under the Montreal Protocol has halted the depletion of the ozone layer and allowed it to start recovering, but much remains to be done to ensure a steady recovery.

The ozone layer

The ozone layer is a natural layer of gas in the upper atmosphere that protects humans and other living things from harmful ultraviolet (UV) radiation from the sun.

Although ozone is present in small concentrations throughout the atmosphere, most (around 90%) exists in the stratosphere, a layer 10 to 50 kilometres above the Earth's surface. The ozone layer filters out most of the sun's harmful UV radiation and is therefore crucial to life on Earth.

Ozone depletion

Scientists discovered in the 1970s that the ozone layer was being depleted.

Atmospheric concentrations of ozone vary naturally depending on temperature, weather, latitude and altitude, while substances ejected by natural events such as volcanic eruptions can also affect ozone levels.

However, these natural phenomena could not explain the levels of depletion observed and scientific evidence revealed that certain man-made chemicals were the cause. These ozone-depleting substances were mostly introduced in the 1970s in a wide range of industrial and consumer applications, mainly refrigerators, air conditioners and fire extinguishers.

Ozone hole

Ozone depletion is greatest at the South Pole. It occurs mainly in late winter and early spring (August-November) and peak depletion usually occurs in early October, when ozone is often completely destroyed in large areas.

This severe depletion creates the so-called "ozone hole" that can be seen in images of Antarctic ozone, made using satellite observations. In most years, the maximum area of the hole is bigger than the Antarctic continent itself. Although ozone losses are less radical in the Northern Hemisphere, significant thinning of the ozone layer is also observed over the Arctic and even over continental Europe.

Most of the ozone-depleting substances emitted by human activities remain in the stratosphere for decades, meaning that ozone layer recovery is a very slow, long process. The hole grew in the years following ratification of the Montreal Protocol, due to the lag caused by the fact that ozone-depleting substances remain in the stratosphere for a long time. The maximum size of the ozone hole is now decreasing.

For the status of the currently ongoing ozone hole, you can visit the Copernicus web site

Effects of ozone depletion for humans and the environment

Ozone layer depletion causes increased UV radiation levels at the Earth's surface, which is damaging to human health.

Negative effects include increases in certain types of skin cancers, eye cataracts and immune deficiency disorders. UV radiation also affects terrestrial and aquatic ecosystems, altering growth, food chains and biochemical cycles. Aquatic life just below the water's surface, the basis of the food chain, is particularly adversely affected by high UV levels. UV rays also affect plant growth, reducing agricultural productivity.

Action to protect the ozone layer

The Montreal Protocol

In 1987, to address the destruction of the ozone layer, the international community established the Montreal Protocol on ozone-depleting substances. It was the first international treaty to be signed by all countries of the world and is considered the greatest environmental success story in the history of the United Nations.

The Montreal Protocol's objective is to cut down the production and consumption of ozone-depleting substances, in order to reduce their presence in the atmosphere and thus protect the Earth's ozone layer.

The chart below shows the decreasing consumption of ozone-depleting substances covered by the Montreal Protocol.

Source: European Environment Agency

EU regulation

EU legislation on ozone-depleting substances is among the strictest and most advanced in the world. Through a series of regulations, the EU has not only implemented the Montreal Protocol but has often phased out dangerous substances faster than required.

The current EU 'Ozone Regulation' ( Regulation (EC) 1005/2009) contains a number of measures to ensure a higher level of ambition. While the Montreal Protocol regulates the production of these substances and their trade in bulk, the Ozone Regulation prohibits their use in most cases (certain uses are still permitted in the EU). Moreover, it regulates not only substances in bulk, but also those contained in products and equipment.

The EU Ozone Regulation also sets licensing requirements for all exports and imports of ozone-depleting substances and regulates and monitors not only substances covered by the Montreal Protocol (over 90 chemicals), but also some that are not covered (five additional chemicals called 'new substances').

For further details, see the Ozone Regulation section.

Impact of global action & remaining challenges

Global consumption of ozone-depleting substances has been reduced by some 98% since countries began taking action under the Montreal Protocol. As a result, the atmospheric concentration of the most aggressive types of ozone-depleting substances is falling and the ozone layer is showing the first signs of recovery.

Nevertheless, the ozone layer is not expected to recover fully before the second half of this century. This is because once released, ozone-depleting substances stay in the atmosphere for many years and continue to cause damage.

Much remains to be done to ensure the continued recovery of the ozone layer and to reduce the impact of ozone-depleting substances on the Earth's climate.
Maximum ozone hole extent over the southern hemisphere, from 1979 to 2019. The images below show analyses of total ozone over the Antarctic by Copernicus. The blue colours indicate the lowest ozone amounts, while yellow and red indicate higher ozone amounts.

Source: European Environment Agency

Actions required globally to continue the recovery of the ozone layer are:

Ensuring that existing restrictions on ozone-depleting substances are properly implemented and global use of ozone-depleting substances continue to be reduced.

Ensuring that banks of ozone-depleting substances (both in storage and contained in existing equipment) are dealt with in an environmentally-friendly manner and are replaced with climate-friendly alternatives.

Ensuring that permitted uses of ozone-depleting substances are not diverted to illegal uses.

Reducing use of ozone-depleting substances in applications that are not considered as consumption under the Montreal Protocol.

Ensuring that no new chemicals or technologies emerge that could pose new threats to the ozone layer (e.g. very short-lived substances).

Relationship between ozone-depleting substances & climate change

Interaction between ozone depletion and climate change

Source: GRID-Arendal

Most man-made ozone-depleting substances are also potent greenhouse gases. Some of them have a global warming effect up to 14,000 times stronger than carbon dioxide (CO ₂), the main greenhouse gas.

Therefore, the global phase-out of ozone depleting substances such as hydrochlorofluorocarbons (HCFCs) and chlorofluorocarbons (CFCs) has also made a significant positive contribution to the fight against climate change.

On the other hand, the global phase-out has led to a large increase in the use of other types of gases, to replace ozone depleting substances in various applications. These fluorinated gases ('F-gases') do not damage the ozone layer, but do have a significant global warming effect. Therefore, in 2016, Parties to the Montreal Protocol agreed to add the most common type of F-gas, hydrofluorocarbons (HFCs), to the list of controlled substances.

For more information, see the Fluorinated greenhouse gases section.

Documentation

Statistics on progress in phasing out ozone-depleting substances

European Environment Agency (EEA)

The EEA produces annual reports on the production, import, export, destruction and use of ozone-depleting substances in the European Union

EEA charts and indicators on the production and consumption of ozone-depleting substances

Ozone layer depletion

Alternatives for ozone-depleting substances

Faq

Protection of the ozone layer: Questions and Answers

Concentrations of ozone in the atmosphere vary naturally according to temperature, weather, latitude and altitude. Furthermore, substances ejected by natural events such as volcanic eruptions can have measurable impacts on ozone levels. However, natural phenomena cannot explain the current levels of ozone depletion.

The scientific evidence shows that certain man-made chemicals are responsible for the creation of the Antarctic ozone hole and the global ozone losses. These chemicals are industrial gases which have been used for many years in a range of products and applications including aerosol sprays, refrigerators, air conditioners, fire extinguishers and crop fumigation.

ODS are broken down by sunlight in the stratosphere, producing halogen (e.g. chlorine or bromine) atoms, which subsequently destroy ozone through a complex catalytic cycle. Ozone destruction is greatest at the South pole where very low stratospheric temperatures in winter create polar stratospheric clouds. Ice crystals formed in these clouds provide a large surface area for chemical reactions, accelerating catalytic cycles. Since the destruction of ozone involves sunlight, the process intensifies during spring time, when the levels of solar radiation at the pole are highest, and polar stratospheric clouds are continually present.

Ozone destruction is greatest at the South Pole. It occurs mainly in late winter and early spring (August-November). Peak depletion usually occurs in early October when ozone is often completely destroyed in large areas. This severe depletion creates the so-called "ozone hole" that can be seen in images of total Antarctic ozone made using satellite observations. In most years the maximum area of the ozone hole is bigger than the area of the Antarctic continent itself. You can see videos on the formation of the ozone hole in the last years on the Copernicus web site.

Although ozone losses are less radical in the northern hemisphere, significant thinning of the ozone layer is also observed over the Arctic, and even over continental Europe/the EU. The ozone loss over the Arctic is however usually less severe than over the Antarctic and is more variable from year to year due to the climatic and geographical situation in the Arctic. Nevertheless, in March 2011 not only a thinning but an actual ozone hole was observed over the Arctic and parts of Europe for the first time.

Increased health costs are the most important direct economic impact of increased UV radiation. The medical expenses for millions of additional cases of skin cancers and eye cataracts pose a challenge to health care systems, particularly in less developed countries. Increased UV radiation also reduces the lifetime and tensile properties of certain plastics and fibers.

Indirect economic impacts include a range of additional costs, for instance for combatting climate change or as a result of reduced fish stocks.

Ozone-depleting substances are still present in many older types of equipment and appliances so awareness of how to deal with these is crucial. Here are some practical things individuals can do to help protect the ozone layer:

Make sure that old refrigerators and air conditioners are disposed of safely by giving them to a recycling yard. Take care not to damage the cooling circuit which contains the ODS;

Ensure technicians repairing your refrigerator or air conditioner recover and recycle the old ODS so they are not released into the atmosphere;

When renovating your house, make sure that old insulation foams containing ODS are disposed of as environmentally hazardous waste;

Inform yourself about ozone depletion through further reading, and suggest activities at your children's school to increase awareness of the problem and initiate local action.

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The EU 'Ozone Regulation' - Regulation (EC) 1005/2009 on substances that deplete the ozone layer - provides the legal basis for the protection of the... Licences & reporting for uses in the EUThe import and export of ozone-depleting substances (ODS), as well as their production for laboratory and...

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"Cars, trucks and SUVs are the some of the biggest contributors to ozone buildup. The engine exhaust in your car creates nitrogen buildup, so the more you drive, the more your vehicle creates."

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The ozone layer, a fragile shield of gas, protects the earth from the harmful portion of the rays of the sun, thus helping preserve life on the planet. In our biosphere, there are four imperative layers -- troposphere, stratosphere, mesosphere and thermosphere. Out of them, stratosphere is very important zone as it carries ozone (O3). Ozone, a three-atom isotope is unstable gas. It is formed and disintegrated by natural processes.

Since 1995, the September 16 has been observed every year as "Ozone layer protection" as per the decision of UN General Assembly adopted on December 19, 1994 in order to raise awareness about the damage being done to the ozone layer through chlorofluorocarbon emissions. The theme of this year is "Keep cool and carry on, the Montreal Protocol."
Ozone absorbs ultraviolet solar radiation and saves the earth's surface from becoming too hot. Ozone layer in the lower atmosphere (lower stratosphere), is a life saving and defensive layer for all biota in the biosphere. In fact, ozone layer is like an umbrella which protects all forms of life on the earth from ultraviolet radiation.

It has been estimate that combustion of a unit of LNG provides 600 times more energy compared to combustion of a unit of natural gas. Secondly, it is comparatively more environment friendly and according to shell, it can emerge as a lower-carbon transport fuel all over the world. While fuels aggravate environmental pollution by depleting the ozone layer, use of LNG will significantly reduce emission of harmful greenhouse gases and nitrogen dioxide into the atmosphere. Thirdly, transportation of LNG is easier than others forms of energy.

But due to the internal actions of the earth, unplanned industrialization and industrialization, deforestation, production and use of atomic and chemical weapons, enormous use of agrochemicals, unexpected bring into play of fuel, production and use of luxurious products and variation of the density of the sunlight etc, ozone layer is now beneath risk.

Ozone layer exhaustion refers to thinning of stratospheric ozone layer lying between 12 and 35 km height in the atmospheric from sea level. Ozone creation and depletion are natural processes which operate continuously in nature. But ozone depletion by anthropogenic factors is a serious environmental problem as man-induced ozone depletion cannot be automatically reversed unless preventive measures adopted in time. The release of CFC's (chlorofluorocarbons) from specific appliances -- air conditioners, refrigerators, hair dryers, fire extinguishers etc. break ozone(O3?O2+O) and cause ozone depletion which allows more solar ultraviolet rays to reach the earth's surface and increase air temperature.

Apart from that, green house gases are detrimental to ozone layer. The gases with the properties of greenhouse are called green house gases -- carbon dioxide (CO2), nitrogen oxides (NO, NO2), methane (CH4), water vapour (H2o) etc. CO2 is considered most hazardous green house gas which is guilty for global warming. The emissions of carbon dioxide from anthropogenic sources -- burning of coal and wood, mineral oil etc. are rapidly mounting nowadays.

IPCC synthesis report on climate change (2001) mentions: in 1988 the car dioxide concentration was 350-360 ppm and it would be 405-560 ppm (2025), 445-640ppm (2050) and 540-970ppm (2100). Global mean temperature would be 0.4-1.10 c by 2025, 0.8-2.60c within 2050 and by 2100 it 1.4-5.80c. In addition, global mean sea level will also rise -- 3-14 cm by 2025, 5-32 by 2050 and 9-88 cm by 2100.

Figure mentions, environmental insurgencies -- fast rate of melting of Greenland ice sheets, warming of ocean water at global level, gradual rise of sea level, spreading of tropical diseases towards temperature and polar regions, shifting of seasonal weather phenomena and changes in precipitation patterns will be more in coming years. Natural disasters -- flood, cyclone, high tide etc. will get higher; coastal areas and low lands will go under water, desertification will go up, agricultural production will drop off, global biodiversity will be in danger, natural heritages would be smashed, flow of rivers water will change, fisheries and forest will be dented, water security will be under stress and various health diseases will materialize.

In this context, we have to bring to an end the use of chlorofluorocarbons, control the smoke of brick fields, industries and vehicles; impede the use of wood and bio-fuels, expand the programs of planting trees all over the country -- particularly in coastal areas; make good contracts with the experts of environmental security and taking necessary information on global climate, appeal to the global community to expand their technical and monitoring cooperation to face the challenges of climate variation, set up effective and sustainable policies, strategies to face the implications of global warming and amplify the public awareness on ozone layer security and green house gases. Incidences of global environmental insecurity are becoming increasingly diverse and more frequent due to the ozone layer depletion. Third world countries who are occupying the lowest rungs of the development ladder will be the greatest guiltless sufferers. Normally, environmental crisis is the consequence of affluence and poverty. The poorer countries have slighter means to undertake crises.

The 7.7 billion people inhabiting the earth may be living within different geographic and political units but they are global community under a global environmental umbrella. The phase-out of controlled using of ozone depleting substances and the related reductions have not only helped protect the ozone layer for this and future generations, but have also contributed significantly to global efforts to address climate change; furthermore, it has protected human health and ecosystems by limiting the harmful ultraviolet radiation from reaching the earth. All we -- mass people, environmentalists, engineers, chemists, biologists, researchers and political bodies have to come forward to prevent ozone layer.

Shishir Reza is environmental analyst, Bangladesh Economic Association and Sharmin Akter, urban planner, Bangladesh Institute of Planners

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Pros and cons of Ozone layer diminution - Op-Ed - observerbd.com

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The ozone layer, a fragile shield of gas, protects the earth from the harmful portion of the rays of the sun, thus helping preserve life on the planet. In our biosphere, there are four imperative layers -- troposphere, stratosphere, mesosphere and thermosphere. Out of them, stratosphere is very important zone as it carries ozone (O3).

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"Protecting the ozone layer could also stop climate change. Because the radiation from the sun could also cause skin cancer and more skin problems."

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A significant reduction in the consumption of ozone-depleting substances (ODS) has been achieved globally since 1986. This reduction has largely been driven by the 1987 United Nations Environment Programme (UNEP) Montreal Protocol.

The largest historical extent of the ozone hole - 28.4 million square kilometres - occurred in September 2000. This area is equivalent to almost seven times the territory of the EU.

The 2021 ozone hole has been similar in depth and size to 2020.

Depletion of stratospheric ozone occurs over both hemispheres of the Earth. However, this phenomenon is significantly less severe in the northern hemisphere (Arctic) than in the southern hemisphere (Antarctica). This is the case because, year-to-year, meteorological variability is larger over the Arctic than over the Antarctic. Furthermore, temperatures in the stratosphere do not remain low for a long time in the Arctic as in the case in the Antarctic.

Generally, concentration levels of 220 Dobson Units (DU, marked by the thick contour in Figure 1) or less (represented in blue colours in Figure 1) are considered to show severe ozone depletion and constitute the so-called ozone hole. This is only apparent in the southern hemisphere. Here, the largest historical extent of the ozone hole - 28.4 million km ² (Figure 1 and 2) - occurred in September 2000. This area is equivalent to almost seven times the territory of the EU.

Figure 1. Maximum ozone hole extent over the southern hemisphere, from 1979 to 2021

Note: Copernicus analyses of total ozone column over the Antarctic. The blue colours indicate lowest ozone columns, while yellow and red indicate higher ozone columns. Ozone columns are commonly measured in Dobson Units. One Dobson Unit is the number of molecules of ozone that would be required to create a layer of pure ozone 0.01 millimetres thick at a temperature of 0 degrees Celsius and a pressure of 1 atmosphere. 300 DU corresponds to 3 millimetres of ozone.

Data source: Copernicus Atmosphere Monitoring Service (CAMS).

Overall, the ozone hole has shown signs of healing since 2000, which is predominantly attributable to phasing out ozone-depleting substances under the Montreal Protocol. At the same time, the extent of the ozone hole is strongly driven by stratospheric temperature, with warmer temperatures leading to a smaller ozone hole, such as in 2019 (for more information, visit the website of the Copernicus Atmosphere Monitoring Service).

However, this is not directly attributable to anthropogenic climate change, since greenhouse gases generally have a cooling effect in the stratosphere, while they contribute to global warming in the troposphere. This stratospheric cooling has a positive effect on ozone recovery with the exception of the polar regions. Here, very low temperatures can lead to an increase in the formation of polar stratospheric clouds, which facilitate ozone depletion. The ozone hole can also be periodically influenced by volcanic eruptions, increasing the stratospheric particle load and thereby depleting ozone. This partially explains those occasional years during which the ozone hole is comparatively large, e.g. in 2015 (27.9 million km²).

Figure 2. Maximum ozone hole area hole

Note: The ozone hole is a region of exceptionally depleted ozone in the stratosphere over the Antarctic. All figures are in million square kilometres.

Data source: Copernicus Atmosphere Monitoring Service (CAMS).

This year's ozone hole over the southern hemisphere showed a maximum area of 24.8 million km² in late September (Figure 2) and resembles the one from 2019 (24.0 million km2). The 2021 ozone hole has been one of the larger and deeper ones in recent years and was larger than the average over the last five and ten years (20.0 and 21.4 million km², respectively). According to researchers from the Copernicus Atmosphere Monitoring Service, colder-than-average temperatures together with strong winds in the stratosphere circling Antarctica contributed to the large 2021 ozone hole size. Ozone loss in the northern hemisphere is usually much more limited compared to the southern hemisphere. In Artic spring 2020, however, ozonesonde measurements showed ozone depletion that has been explained to occur due to unusually strong, long-lasting cold temperatures in the stratosphere.

The 2019 ozone hole has been a very small and short-lived one, which was mostly driven by special meteorological conditions. In particular, August and September 2019 showed exceptionally high temperatures in altitudes between 20 and 30 km above the ground of the Antarctic, stopping the formation of icy clouds that usually trap ozone-depleting molecules that, when released during southern hemispheric springtime, trigger ozone destruction. Taken together, the mitigation of ozone depletion is still very fragile and scientific evidence suggests that more action is still required to remove pressure on the ozone layer caused by ODS.

Browse the for more information on ozone-depleting substances.

Photo: © Arif Miletli, Sustainably Yours /EEA

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What is the current state of the ozone layer?

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The ozone layer sits in the stratosphere between 15 km and 30 km above the earth, and shields us and other living things from the sun's harmful ultraviolet radiation. Ozone layer depletion could have serious effects on human health and the environment.

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"The ozone layer is depleting due to the chemicals we use everyday. The depletion causes the humans to be more prone to skin cancer."

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The story of three tricky oxygen atoms, and the spacecraft designed to help us understand them.

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"The ozone layer protects life on earth, from absorbing high levels of the sun"

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Ozone-Protection Treaty Had Climate Benefits, Too, Study Says - The Earth Institute - Columbia University

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"The ozone layer in the stratosphere absorbs a portion of the radiation from the sun, preventing it from reaching the planet's surface. Most importantly, it absorbs the portion of UV light called UVB."

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Explore National Geographic. A world leader in geography, cartography and exploration.

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"The ozone layer is a term for the high concentration of ozone, 'it is stratosphere around 15-30km above the earths surface. it cover the entire planet and absorbs harmful ultraviolet rays from the sun."

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Skin cancers in a world without the Montreal Protocol A.B.C

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Skin cancers in a world without the Montreal Protocol A.B.C

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"If we had no ozone layer we would be prone to skin cancer because the ozone layer takes away most ultraviolet rays."

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The ozone layer is a region of high ozone concentration in the stratosphere, 15 to 35 kilometres above Earth's surface. The ozone layer acts as an invisible shield and protects us from harmful ultraviolet (UV) radiation from the sun. In particular, the ozone layer protects us from the UV radiation, known as UV-B, which causes sunburn.

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The ozone layer protects us by absorbing ultraviolet radiation,by wearing sunglasses and hats.

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The Earth's protects all life from the sun's harmful radiation, but human activities have damaged this shield. Less ozone-layer protection from will, over time, damage crops and lead to higher skin cancer and cataract rates.

I. The Ozone Layer

The Earth's atmosphere is composed of several layers. The lowest layer, the , extends from the Earth's surface up to about 6 miles or 10 kilometers (km) in altitude. Virtually all human activities occur in the troposphere. Mt. Everest, the tallest mountain on the planet, is only about 5.6 miles (9 km) high. The next layer, the , continues from 6 miles (10 km) to about 31 miles (50 km). Most commercial airplanes fly in the lower part of the stratosphere.

Most atmospheric ozone is concentrated in a layer in the stratosphere, about 9 to 18 miles (15 to 30 km) above the Earth's surface (see the figure below). Ozone is a molecule that contains three oxygen atoms. At any given time, ozone molecules are constantly formed and destroyed in the stratosphere. The total amount has remained relatively stable during the decades that it has been measured.

The ozone layer in the stratosphere absorbs a portion of the radiation from the sun, preventing it from reaching the planet's surface. Most importantly, it absorbs the portion of UV light called . UVB has been linked to many harmful effects, including skin cancers, cataracts, and harm to some crops and marine life.

Scientists have established records spanning several decades that detail normal ozone levels during natural cycles. Ozone concentrations in the atmosphere vary naturally with sunspots, seasons, and latitude. These processes are well understood and predictable. Each natural reduction in ozone levels has been followed by a recovery. Beginning in the 1970s, however, scientific evidence showed that the ozone shield was being depleted well beyond natural processes.

II. Ozone Depletion

When chlorine and bromine atoms come into contact with ozone in the stratosphere, they destroy ozone molecules. One chlorine atom can destroy over 100,000 ozone molecules before it is removed from the stratosphere. Ozone can be destroyed more quickly than it is naturally created.

Some compounds release chlorine or bromine when they are exposed to intense UV light in the stratosphere. These compounds contribute to ozone depletion, and are called ozone-depleting substances (). ODS that release chlorine include (CFCs), (HCFCs), , and . ODS that release bromine include and . Although ODS are emitted at the Earth's surface, they are eventually carried into the stratosphere in a process that can take as long as two to five years.

In the 1970s, concerns about the effects of ozone-depleting substances () on the stratospheric prompted several countries, including the United States, to ban the use of chlorofluorocarbons () as propellants. However, global production of CFCs and other ODS continued to grow rapidly as new uses were found for these chemicals in refrigeration, fire suppression, foam insulation, and other applications.

Some natural processes, such as large volcanic eruptions, can have an indirect effect on ozone levels. For example, Mt. Pinatubo's 1991 eruption did not increase stratospheric chlorine concentrations, but it did produce large amounts of tiny particles called (different from consumer products also known as aerosols). These aerosols increase chlorine's effectiveness at destroying ozone. The aerosols in the stratosphere create a surface on which CFC-based chlorine can destroy ozone. However, the effect from volcanoes is short-lived.

Not all chlorine and bromine sources contribute to ozone layer depletion. For example, researchers have found that chlorine from swimming pools, industrial plants, sea salt, and volcanoes does not reach the stratosphere. In contrast, ODS are very stable and do not dissolve in rain. Thus, there are no natural processes that remove the ODS from the lower atmosphere.

One example of ozone depletion is the annual ozone "hole" over Antarctica that has occurred during the Antarctic spring since the early 1980s. This is not really a hole through the ozone layer, but rather a large area of the stratosphere with extremely low amounts of ozone.

Ozone depletion is not limited to the area over the South Pole. Research has shown that ozone depletion occurs over the latitudes that include North America, Europe, Asia, and much of Africa, Australia, and South America. More information about the global extent of ozone depletion can be found in the Scientific Assessment of Ozone Depletion: 2018 developed by the United Nations Environment Programme.

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The Earth's protects all life from the sun's harmful radiation, but human activities have damaged this shield. Less ozone-layer protection from will, over time, damage crops and lead to higher skin cancer and cataract rates. The Earth's atmosphere is composed of several layers.

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"Since 2000 parts of the ozone layer have recovered at a rate of 2 percent. The ozone layer's souther hemisphere is on track to heal completely by 2050, and the polar regions by the following decade"

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The phaseout of controlled uses of ozone-depleting substances has not only helped replenish the protective layer for future generations but is also helping guard human health by filtering harmful rays from reaching Earth, said UNEP shared in a statement.

The recognition of this success comes on World Ozone Day, marked 16 September. This year celebrates "32 Years and Healing"; a commemoration of the international commitment to protect the ozone later and the climate under the historic Montreal Protocol, which has led to the phase-out of 99 per cent of ozone-depleting chemicals in refrigerators, air-conditioners and other consumer products.

Since 2000, parts of the ozone layer have recovered at a rate of 1-3 per cent every ten years, the latest Scientific Assessment of Ozone Depletion estimates. At projected rates the "Northern Hemisphere and mid-latitude ozone will heal completely by the 2030's", UNEP said, with the Southern Hemisphere repaired by the 2050's, and Polar Regions in the following decade.

UN Secretary-General, António Guterres said "we must be careful not to neglect the ozone layer," as we "rightly focus our energies on tackling climate change", spotlighting the importance of preventing threats posed by emission of ozone-depleting gases.

Regenerating the ozone has helped curb the effects of climate change - with approximately 135 billion tonnes of carbon dioxide emissions from 1990 to 2010 averted by a strong protective shield.

As of late last year, the World Meteorological Organization (WMO) reported the global concentration of carbon dioxide and other greenhouse gases is still steadily on the rise, with consequential warming effects on the planet and ozone-teardown.

Damaging effects of ozone-depleting substances allow increased ultraviolet (or UV) rays to reach the earth, increasing incidents of skin cancers, eye cataracts, compromised immune systems and harm to agricultural lands and forests.

The Montreal Protocol is, to date, the only UN treaty to be adopted by all Member States, with all parties sharing responsibilities relating to phasing out ozone-depleting substances, controlled trade of such substances, annual data reporting and other matters.

"We can celebrate success," UNEP said, "but we must all push to keep hold of these gains, in particular by remaining vigilant and tackling any illegal sources of ozone-depleting substances as they arise."

Looking forward, the agency has called for wholehearted support of the Kigali Amendment to the Montreal Protocol, which entered into force on 1 January of this year.

The agreement targets the phasing of hydrofluorocarbons (HFCs), climate-warming gases, which could avoid up to 0.4 degrees Celsius of global temperature rise by end of the century.

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Ozone on track to heal completely in our lifetime, UN environment agency declares on World Day.

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At the current momentum, scientists predict the planet's protective shield of gas - or ozone layer as we know it - will be completely healed as far as some regions of the planet are concerned, by the 2030's, the UN's environmental agency (UNEP) revealed on Monday.