Climate Action

Ozone layer


EU legislation to protect the ozone layer is among the strictest and most advanced in the world. Europe has not only implemented what has been agreed under the Montreal Protocol on protecting the ozone layer but has often phased out dangerous substances faster than required.

The importance of a healthy ozone layer

The ozone layer in the upper atmosphere protects humans and other organisms against ultraviolet (UV) radiation from the sun. In the 1970s scientists discovered that certain man-made chemicals deplete the ozone layer, leading to an increased level of UV radiation reaching the Earth.

Overexposure to UV radiation carries a number of serious health risks for humans. It causes not only sunburn but also greater incidences of skin cancer and eye cataracts.

There are also serious impacts on biodiversity. For example, increased UV radiation reduces the levels of plankton in the oceans and subsequently diminishes fish stocks. It can also have adverse effects on plant growth, thus reducing agricultural productivity. A direct negative economic impact is the reduced lifespan of certain materials like plastics.

Ozone-depleting substances

Gases that damage the ozone layer - ozone-depleting substances (ODS) - have been used in a wide range of industrial and consumer applications, mainly in refrigerators, air conditioners and fire extinguishers. They have also been used as aerosol propellants, solvents and blowing agents for insulation foams.

The main ODS being phased out under the Montreal Protocol are

  • chlorofluorocarbons (CFCs)
  • hydrochlorofluorocarbons (HCFCs)
  • halons
  • carbon tetrachloride and
  • methyl bromide.

The link to climate change

Dramatic cloudscape © iStockphoto

Most man-made ODS are also very potent greenhouse gases. Some of them are up to 14 000 times stronger than carbon dioxide (CO2), the main greenhouse gas.

Eliminating these substances therefore also contributes significantly to the fight against climate change. The international phase-out of ODS has so far delayed the impact of climate change by 8-12 years.

On the other hand, phasing out ODS has led to a strong growth of other highly warming gases, such as the HFCs (hydrofluorocarbons). In 2016, Parties to the Montreal Protocol agreed to add HFCs to the list of controlled substances.

EU at the forefront

The international community established the Montreal Protocol on substances that deplete the ozone layer in 1987. Policies put in place by the EU and its Member States often go beyond the requirements of the Montreal Protocol.

Already by 2010, the EU had significantly reduced its consumption of the main ozone-depleting substances, 10 years ahead of its obligation under the Montreal Protocol.

Furthermore, the EU has put in place controls on uses of ozone-depleting substances that are not considered as consumption under the Montreal Protocol, such as the use of ODS as a feedstock in the chemical industry.

The EU has also gone beyond the requirements of the Protocol in banning the use of the toxic chemical methyl bromide for any kind of fumigation.

EU legislation has not only been very effective in controlling ozone-depleting substances but has also acted as a driver for the development of innovative technologies. These include

  • alternatives to methyl bromide
  • new blowing agents for insulation foam
  • CFC-free metered dose inhalers for the treatment of asthma, and
  • innovative non-halon fire-fighting systems, for example on ships and airplanes.

But the job is not done yet …

The global consumption of ODS has been reduced by some 98% since countries started taking action under the Montreal Protocol.

As a result, the atmospheric concentration of the most aggressive types of ODS is falling and the ozone layer is showing the first signs of recovery. Nevertheless, it is not expected to recover fully before the second half of this century.

Much remains to be done to ensure the continued recovery of the ozone layer and to reduce the impact of ODS on climate change.

Actions needed are:

  • Ensuring that the existing restrictions on ODS are properly implemented and worldwide use of ODS continues to be reduced;
  • Ensuring that ODS are replaced with climate-friendly alternatives;
  • Recovering ODS from existing equipment and buildings;
  • Preventing illegal trade in ODS;
  • Reducing use of ODS in applications that are not considered as consumption under the Montreal Protocol.


The European Commission supports research projects in the field of ozone layer protection.

Some examples:

  • The RECONSILE project aimed to improve model representations of key processes dominating chemistry, microphysics and the dynamics of Arctic stratospheric ozone loss.
  • SHIVA aimed to reduce uncertainties in present and future stratospheric halogen loading and ozone depletion resulting from climate feedbacks between emissions and transport of ozone depleting substances (ODS).
  • ICEPURE investigated the impact of climatic and environmental factors on personal ultraviolet radiation exposure and human health.

Statistics on progress in phasing out ODS

Ozone observations



Other documents


Protection of the ozone layer: Questions and Answers (September 2012)

What is the ozone layer?

The ozone layer is a natural layer of gas in the upper atmosphere which protects humans and other living things from the harmful ultraviolet (UV) rays of the sun. Although ozone (O3) is present in small concentrations throughout the atmosphere, most ozone (about 90%) exists in the stratosphere, in a layer between 10 and 50 km above the surface of the earth. This ozone layer performs the essential task of filtering out most of the sun's biologically harmful UV radiation.

What causes the depletion of the ozone layer?

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.

What is the Ozone Hole?

Ozone hole © Source NASA
Ozone leged © Source NASA

Ozone hole, October 2011
Low concentrations of ozone are
indicated in purple and blue
Source: NASA

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.

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.


What are the health effects of ozone depletion?

Increased UV levels at the earth's surface are damaging to human health. The negative effects include increases in the incidence of certain types of skin cancers, eye cataracts and immune deficiency disorders. Increased penetration of UV results in additional production of ground level ozone, which causes respiratory illnesses.

What are the environmental effects of ozone depletion?

UV affects terrestrial and aquatic ecosystems, altering growth, food chains and biochemical cycles. In particular, aquatic life occurring just below the surface of the water, which forms the basis of the food chain, is adversely affected by high levels of UV radiation. UV rays also have adverse effects on plant growth, thus reducing agricultural productivity. Furthermore, depletion of stratospheric ozone also alters the temperature distribution in the atmosphere, resulting in a variety of environmental and climatic impacts.

What are the economic effects of ozone depletion?

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.

Will the ozone layer recover?

Despite existing regulation of ODS, there continues to be severe ozone depletion. This is because once released, ODS stay in the atmosphere for many years and continue to cause damage. However, since smaller and smaller amounts of ODS are being released, the first signs of recovery of the ozone layer are visible. Nevertheless, because of the long lifetime of ODS, and unless additional measures are taken, the ozone layer is unlikely to recover fully before the second half of the century.

What can I do to protect the ozone layer?

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.

How can I protect myself from UV radiation?

There is a direct link between increased exposure to UV radiation and a higher risk of contracting certain types of skin cancers. Risk factors include skin type, sunburn during childhood, and exposure to intense sunlight. Recent changes in lifestyle, with more people going on holiday and deliberately increasing their exposure to strong sunlight, are partly responsible for an increase in malignant skin cancers. To minimise the risk of contracting skin cancer, cover exposed skin with clothing or with a suitable sunscreen or sun cream, wear a hat, and wear UV-certified sunglasses to protect the eyes.

What about the positive effects of UV radiation?

While an increased amount of UV radiation is bad for human health, too little exposure can also have negative effects. These are mainly related to the reduced vitamin D production in the skin which is induced by UV radiation. Under-supply of vitamin D is the cause of a number of illnesses such as osteoporosis, osteomalacia (softening of the bones), rickets or cardiovascular problems. Dark-skinned people are particularly vulnerable to a decrease in natural UV radiation. However, most people get adequate exposure to UV radiation in their daily lives. For healthy humans, there is no medical reason to seek additional exposure.