New Air Pollution Problems

Among the atmospheric pollutants, there is new emphasis on tropospheric ozone, both because of its impact on the climate as a greenhouse gas, and because of the key chemical role that ozone plays in atmospheric chemical reactions, health impacts and environmental damage. Small particulates less than 10 microns in diameter are another recently recognized dangerous pollutant, causing early death among those suffering from lung and heart disease. This fine dust is produced by diesel exhausts, power stations and industry. The UK has estimated the safe level for these particles is exceeded in most cities 10 per cent of the time, causing 2,000 to 10,000 extra deaths a year (WHO, 1995; Martinson, 1996). Aerosols need to receive more attention, as they are now believed to play an important role in the climate change issue, but this has not been well assessed or quantified.

While acid rain has long been recognized as a problem in the industrial north, there is now evidence of the increasing danger of acid rain in South-East Asian countries (WMO). Emissions of sulphur dioxide have declined significantly in Europe and North America with reduced coal use and the application of emission clean-up techniques, and further progress is expected (EEA, 1995). This has reduced the sulphur contribution to acid rain, but surprisingly has also resulted in sulphur deficiencies in some agricultural soils, causing falling yields and the appearance of new diseases. (Schnug, Ewald, et al., 1995) A lack of sulphur may also contribute to increasing ozone pollution by reducing the ability of plants to oxidize it.

The same improvement has not been seen in nitrogen oxides and other pollutants from vehicles, where the reduction in emissions due to catalytic converters has been counterbalanced by a growing number of vehicles. Urban air quality in Europe has thus continued to deteriorate (EEA, 1995).

The worst pollution problems may appear in unexpected places, such as the Arctic, where high levels of toxins such as PCBs, DDT, toxaphene, hexachlorobenzene, chlordane, lindane, dieldrin, mercury and dioxin have been found. There appears to be a global process of distillation where pollutants evaporate in warmer areas, are transported by winds to the Arctic, and then condense out to become concentrated in Arctic food chains (Kidd et al., 1995).