Air Pollution

Air pollution was among the first environmental problems to produce a major governmental response, as exemplified by the lethal London smog of the early 1950s, and some significant improvements have been made in the urban areas of industrialized countries. However as some problems have been controlled, others have emerged.

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 counter-balanced 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).

As if each of the major atmospheric problems were not enough by themselves, they can interact and reinforce each other. Recent research has shown that acid rain and global warming can greatly magnify the effects of ozone layer thinning. In Canada, regional warming has reduced precipitation and thus dissolved organic carbon inputs to lakes, while acidification reduces the productivity of some plants. Together these can raise ultraviolet penetration in lake water from thinning ozone by up to 800 percent, causing increasing damage to lake ecosystems (Schindler, et al., 1996).

EEA. 1995. Europe's Environment 1995. European Environment Agency, Copenhagen.

Kidd, K.A., D.W. Schindler, D.C.G. Muir, W.L. Lockhart and R.H. Hesslein. 1995.  "High concentrations of Toxaphene in fishes from a sub-Arctic lake." Science 269:240-242. 14 July 1995.

Martinson, Jane. 1996. "Big problems from tiny particulates". Financial Times, 17 January 1996, citing reports by UK Committee on the Medical Effects of Air Pollutants, and UK Expert Panel on Air Quality Standards.

Schindler, David W., P.J. Curtis, P.R. Parker and M.P. Stainton. 1996. "Consequences of climate warming and lake acidification for UV-B penetration in North-American boreal lakes." Nature 379:705-708. February 1996.

Schnug, Ewald, et al. 1995. Institute of Plant Nutrition and Soil Science, Brunswick, Germany. Quoted in MacKenzie, Debora. "Killing crops with cleanliness." New Scientist, 23 September 1995, p. 4.

WHO. 1995. WHO expert panel report, cited in Edwards, Rob. "Industry denies dangers of particle pollution". New Scientist, 4 November 1995, p. 4.