Review of the health effects of sulfur oxides.

The pollution in the air is a complex mixture of chemical substances of varying toxicity of which the sulfur oxides are a principal component. Those components which pose the primary hazards to human health have not yet been fully identified, nor have their respective contributions to human disease been fully determined. Efficient and effective control strategies are dependent upon the identification and understanding of these toxic components. Ultimately, the goal of standard-setting should be the development of composite pollution indices rather than control of individual pollutants. Concentrations of SO(2) in the ambient air twice the current standards are associated with adverse health effects. A considerable body of evidence suggests that there may be discernible human health effects from exposure to concentrations approximating the current standards. There is therefore no basis for relaxation of the present standards for sulfur oxides at this time. Since the scientific basis for this judgment is incomplete, further scientific information will be required either to validate the present standards or to justify alteration of these standards.