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.
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.
During the 1980s and 1990s there was a decreasing trend in the ozone concentration over New Zealand which has since stabilised since the 2000s, similar to international trends. 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 ozone concentrations(external link) and the National Institute of Water and Atmospheric Research's (NIWA) information on the ozone hole(external link).
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:
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:
These chemicals have a range of uses, for example, methyl bromide is used as a fumigant for treating primary products for export such as timber (and imported products) to control quarantine pests.
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(external link) (Ministry for the Environment).
You can help to reduce the amount of CFCs entering the atmosphere by:
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:
The Cancer Society(external link) has more information on how to protect yourself from UV rays.