Key Findings of the Impact Assessment of Stratospheric Ozone

Human health:

Non-melanoma skin cancer will increase with any long-term increase of the UV-B radiation, without a threshold value. The percentage increases will not be one-to-one: a sustained ten per cent reduction in ozone would result in a 26 per cent increase in non-melanoma skin cancer. All other things remaining constant, this would mean an increase in excess of 300,000 cases a year, world-wide. There is concern that an increase of the more dangerous cutaneous melanoma could also occur. Skin cancer would affect mainly people with little protective pigment in their skin. Exposure to increased UV-B radiation can cause suppression of the body's immune system, which might lead to an increase in the occurrence or severity of infectious diseases and a possible decrease in the effectiveness of vaccination programmes. Enhanced levels of UV-B radiation can lead to increased damage to the eyes, especially cataracts, which are estimated to increase by 0.6% per 1% of total-column ozone depletion.

Terrestrial plants:

Of the plant species investigated, about half were found to be sensitive to enhanced UV-B radiation, the impact being that plants typically exhibit reduced growth and smaller leaves. In some cases, these plants also show changes in their chemical composition, which can affect food quality and the availability of mineral nutrients. Within species, varieties have different UV-sensitivities, as demonstrated in soybeans. In certain economically important varieties, increased UV-B reduces food yield by up to 25% for exposures simulating 25% total-column ozone depletion.

Aquatic ecosystems:

Increased UV-B irradiance has been shown to have a negative influence on aquatic organisms, especially small ones such as phytoplankton, zooplankton, larval crabs and shrimp, and juvenile fish. Because many of these small organisms are at the base of the marine food web, increased UV-B exposure may have a negative influence on the productivity of fisheries. Increased exposure to UV-B radiation could lead to decreased nitrogen assimilation by prokaryotic micro-organisms and, thereby, to a possible nitrogen deficiency in rice paddies. The potential loss in yield has not yet been quantified.

Tropospheric air quality:

Enhanced levels of surface UV radiation could cause increased atmospheric abundances of several chemically reactive compounds, notably acids, hydrogen peroxide and, in polluted areas, ozone. In unpolluted regions where the concentration of NOx is low, tropospheric ozone should decrease. It is also possible that the atmospheric abundance of particulates could be enhanced.

Materials damage:

Exposure to UV radiation is a significant cause of degradation of many materials, such as wood, plastic coatings, plastics and rubber. The impact is mainly economic. The in-creased damage will be most severe in tropical locations, where the degradation may be increased by high ambient temperatures and sunshine levels.

Source: UNEP (1989)