Changing perspectives on air-pollution stress

Abstract

As more has been learned about the nature of air pollution and more sophisticated techniques have been developed for measurement, it has become apparent that acid rain is only one of an interrelated array of airshed-watershed problems. Despite important reductions in some pollutant emissions, the authors believe the situation today is worse than it appeared to be 15 years ago. Recently scientists have reported data showing that in some locations dry deposition of hydrogen ion, sulfur, and nitrogen in coarse and fine particles and vapors may exceed the same substances measured in bulk precipitation. As scientists learned about acid rain, they also became more aware of photochemical oxidant pollution. Symptoms of ozone damage on crops and natural vegetation have been found in a majority of states. As understanding and measurement ability have increased, estimates of the magnitude of the air pollution problem have grown. The recent measurements of dry deposition, cloud-water deposition, and photochemical oxidant concentrations have greatly increased estimates of airborne pollutants reaching ecosystems. They have shown that the photochemical oxidant problem cannot be separated from the acid-rain problem and that the combined effects may be both episodic and long-term. These findings indicate that regional air pollution is moremore » severe than it was perceived to be 15 years ago. Solving the problem will be extremely difficult and expensive both in terms of monitoring and assessing effects on ecosystems under realistic conditions. The longer the delays in setting an official policy of comprehensive correctional measures, the more environmental damage may occur. Extensive damage, in turn, would increase the cost of measures for protection and recovery.« less