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3. Damage from the long-Range Transport of Air Pollution
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33. Measure taken by many industrialized countries in the 1970s to control urban and industrial air pollution (high chimney stacks, for example) greatly improved the quality of the air in the cities concerned. However, it quite unintentionally sent increasing amounts of pollution across national boundaries in Europe and North America, contributing to the acidification of distant environments and creating new pollution problems. This was manifest in growing damage to lakes, soils, and communities of plants and animals. Failure to control automobile pollution in some regions has seriously contributed to problem.

34. Thus atmospheric pollution, once perceived only as a local urban-industrial problem involving people's health, is now also seen as a much more complex issue encompassing buildings, ecosystems, and maybe even public health over vast regions. During transport in the atmosphere, emissions of sulphur and nitrogen oxides and volatile hydrocarbons are transformed into sulphuric and nitric acids, ammonium salts, and ozone. They fall to the ground, sometimes many hundreds or thousands of kilometres from their origins, as dry particles or in rain, snow, frost, fog, and dew. Few studies of their socio-economic costs are available, but these demonstrate that they are quite large and suggest that they are growing rapidly. They damage vegetation, contribute to land and water pollution, and corrode buildings, metallic structures and vehicles, causing billions of dollars in damage annually.

35. Damage first became evident in Scandinavia in the several thousand lakes in Europe, particularly in southern Scandinavia, and several hundreds in North America have registered a steady increase in acidity levels to the point where their natural fish populations have declined or died out. The same acids enter the soil and groundwater, increasing corrosion of drinking water piping in Scandinavia.

36. The circumstantial evidence indicating the need for action on the sources of acid precipitation is mounting with speed that gives scientists and governments little time to assess it scientifically. Some of the greatest observed damage has been reported in Central Europe, which is currently receiving more than one gramme of sulphur on every square metre of ground each year, at least five times greater than natural background. There was little evidence of tree damage in Europe in 1970. In 1982, the Federal Republic of Germany reported visible leaf damage in its forest plot samples nationwide, amouting in 1983 to 34 per cent, and rising in 1985 to 50 per cent. Sweden reported light to moderate damage in 30 per cent of its forests, and various reports from other countries in Eastern and Western Europe are extremely disquieting. So far an estimated 14 per cent of all European forestland is affected.

37. The evidence is not all in, but many reports show soils in parts of Europe becoming acid throughout the tree rooting layers, particularly nutrient-poor soils such as those of Southern Sweden. The precise damage mechanisms are not /…