UNCERTAINTIES RELATING TO THE HEALTH-EFFECTS OF PARTICULATE AIR-POLLUTION - THE US EPAS PARTICLE STANDARD

Although the epidemiologic associations between urban particulate air pollution and human mortality and morbidity have been accumulating for several years, the causal agents (a specific chemical component, a sp ecific particle size range, one or more pollutant combinations, etc.), and the physiological mechanisms behind the associations have yet to be identified. Significant questions regarding confounding effects due to weather, indoor air pollutant exposures and co-pollutants (that ac company particulate matter) stubbornly remain. The events in the Unite d States began with recent epidemiological associations, followed by a lawsuit forcing the US EPA to accelerate the standard-setting process , and finally controversy over the scientific basis of the new standar d. In contrast to the potential risks posed by particulate air polluti on, many of the sources of such particles are positive contributors to human health; control measures to meet the proposed standard may ther efore produce offsetting enhanced mortality and morbidity. In order to establish the information required for well-informed public health po licies, a substantial research program is needed because of uncertaint ies relating to, the affected individuals, the potential causal agents , and the consequences of particle-control activities. Not only are th e remaining scientific questions significant, but the particle exposur e/health effects associations also call into question some of the curr ent scientific assumptions relating to the nature of effects of popula tion exposures to low concentrations of pollutants. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.