Discharges and emissions of toxic substances into the air and water and onto land can harm or kill organisms and devastate natural communities. Dispersed through activities in agriculture, forestry, mining and other industries, and by municipalities and individuals, these substances are weakening and destroying the bases of major food webs and having major negative impacts on the quality of air, water and land required for the health of all living things.
Despite improvements in the levels of some atmospheric pollutants in North America and Western Europe, resulting from the effective implementation of control measures, and pollution reductions in Eastern Europe and Central Asia, mainly from economic restructuring, significant problems remain. For example, critical loads for acid deposition are still being exceeded for more than 25 per cent of ecosystems in Western and Central Europe, and emissions of nitrogen oxides in North America increased by about 10 per cent from the 1980s to the 1990s (International Joint Commission 1997). These problems are likely to worsen as the economies in Eastern Europe and Central Asia grow stronger, and with the continuing increase in car use in these regions, in the rest of Europe and in North America.