Some human activities release chemicals into the air that remove ozone. Less ozone in the atmosphere increases the amount of ultra-violet (particularly UV-B) rays that reach the earth. Sunburning UV-B is harmful to people and the environment.
On this page: Ozone – a natural screen, Effects of reduced ozone, Ozone-destroying chemicals , Protecting the ozone layer, You can help, Protect yourself
Ozone – a natural screen
Ozone (O3) is an atmospheric gas found mainly in the upper atmosphere. The ozone layer forms a natural screen that absorbs most of the ultraviolet (UV) radiation from sunlight – before it reaches the earth’s surface.
Over the last 15 years the ozone layer covering the Earth has decreased, particularly over Antarctica. During early spring, an ozone ‘hole’ has formed over Antarctica since the late 1970s. Although the hole itself doesn’t move, when the ozone layer rebuilds itself during late spring and early summer the total ozone layer over the Earth gets diluted (reduced).
Check out the Ministry for the Environment's (MfE) information on the ozone layer and the National Institute of Water and Atmospheric Research's (NIWA) information on the ozone hole.
Effects of reduced ozone
In New Zealand it’s estimated that ozone losses since 1980 have caused sunburning radiation to increase by 10 to 12 percent (1996 levels).
Increasing ultraviolet (UV) radiation can cause:
- Health problems for people and animals - more skin cancer, eye damage and damage to the immune system (increasing vulnerability to diseases).
- Reduced plant growth - increased UV radiation can reduce plant photosynthesis and growth.
- Genetic changes - small organisms may have an increased chance of mutation.
- Damage to possessions - materials sensitive to ultra-violet light may age quicker.
Ozone-destroying chemicals
Ozone naturally breaks down and re-forms itself in the upper atmosphere. However, except for areas near the equator, ozone is now being destroyed much faster than it’s being created. The main culprits are synthetic (human-made) chemicals containing bromine and chlorine, such as chlorofluorocarbons (CFCs). CFCs were used as refrigeration agents and propellants in aerosol sprays. Some existing refrigeration systems still contain this chemical.
Other ozone-depleting chemicals include:
- carbon tetrachloride
- methyl bromide
- methyl chloroform
- halons
- hydrobromofluorocarbon
- hydroflurocarbons.
These chemicals have a range of uses, for example, methyl bromide is used for soil sterilisation in strawberry production.
Check out the Ministry for the Environment’s information on ozone-depleting chemicals.
Protecting the ozone layer
In 1998 the New Zealand Government adopted the Montreal Protocol on 'Substances which Deplete the Ozone Layer'. This international protocol called for a freeze of annual use of CFCs to 1986 levels and a reduction in use by 50 percent by 1999.
New Zealand’s Government controls the import and sale of CFCs and halons, and technology and goods made using CFCs. Find out more about the Ozone Layer Protection Act 1996 (Ministry for the Environment).
Waikato Regional Council informs communities and resource users about the effects of ozone-depleting chemicals, and how to manage those chemicals. Find out how our Regional Policy Statement supports Government initiatives for managing this important air pollution problem.
You can help
You can help to reduce the amount of CFCs entering the atmosphere by:
- Disposing of your old refrigerator properly to make sure CFCs aren’t released into the air - recycling depots usually have a place for old refrigerators.
- Maintaining your car’s air conditioning system so it doesn’t leak CFCs.
Protect yourself
New Zealand has a very high rate of melanoma – the deadliest form of skin cancer. We are exposed to high levels of UV, particularly in summer. It’s important to reduce our exposure to UV by:
- avoiding the sun between 11:00am to 4:00pm - particularly during summer
- using sunscreen sun protection factor (SPF) 15 to 30+
- using wrap-around sunglasses to protect your eyes
- staying in the shade when outside
- wearing sun-protective clothing, such as hats and long sleeved shirts.
The Cancer Society has more information on how to protect yourself from UV rays.