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Show A dose-response curve and threshold level of safety has not been developed for PM10. PM10 on high pollution days is chemically different from PM10 on cleaner days. Thus, while epidemiological studies have shown associations between high PM10 pollution days and health effects using regression models, one cannot conclude whether those associations are related to a change in the amount, or dose, of the PM10, or in the precise nature of the particles. Furthermore, evidentiary support for the theory that PM is causing mortality is lacking. The criteria of strength of association, specificity, biological gradient, plausibility, coherence, and experimental evidence as outlined by Dr. Austin B. Hill,5 and endorsed by EPA&, are not satisfied by the current body of association studies. Since a "safe" level for PM10 has not been identified, an estimate of a margin of safety, if there is one, for the PM10 standard cannot be made. The field must await the results of more specific research which addresses the Hill criteria before such estimates can be made with confidence. Both ozone and PM10 irritate the eyes, nose, throat, and lungs. About 14 to 15 percent of individuals over 55 years of age suffer to some extent from chronic obstructive pulmonary disease. For these individuals and for all who suffer from asthma, bronchitis, or other respiratory diseases, elevated levels of air pollution have an immediate and detectable impact on symptoms. Prolonged and daily exposure to respiratory irritants are believed to increase the risk of developing chronic obstructive pulmonary disease.7 References 1. Folinsbee, L.J. & Horvath, S.M. (1986). Persistence of the acute effects of ozone exposure. Aviat Space Environ Med, 57, 1136-1143. 2. United States Environmental Protection Agency. OAQPS Staff Paper. (1996). Review of the national ambient air quality standards for paniculate matter: Policy assessment of scientific and technical information. Page VII-2. (EPA Publication No. EPA-452/R-96-013). Research Triangle Park, North Carolina: Office of Air Quality Planning and Standards. 3. Lyon, J.L. Mori, M. & Gao, R. (1995). Is there a causal association between excess mortality and exposure to PM-10 air pollution? Additional analyses by location, year, season and cause of death. Inhalation Toxicology, 7, 603-614. 4. Lyon, J.L. (1997). Personal communication. University of Utah Health Sciences Center. Department of Family and Preventative Medicine, Salt Lake City, Utah. 5. Hill, A.B. (1965). The environment and disease: Association or causation. (Presidential address). Proceedings of the Royal Society of Medicine, 58, 295-300. 6. United States Environmental Protection Agency. (April 1995). Air Quality Criteria for Paniculate Matter, Volume III of III, pages 12-5 - 12-6. Office of Research and Development, Office of Health and Environmental Assessment, Environmental Criteria and Assessment Office. (EPA Publication No. EPA/600/AP-95/001). 7. Pope, III, C.A., Thun, M.J., Namboodiri, M.M., Dockery, D.W., Evans, J.S., Speizer, F.E., & Heath, Jr., C.W. (1995). Particulate air pollution as a predictor or mortality in a prospective study of U.S. adults. American Journal of Respiratory and Critical Care Medicine, 151, 669-674. About the Author Steven C. Packham is the manager of the cost benefit/risk assessment section of, and the toxicologist for, the State of Utah Division of Air Quality. He received his Ph.D. in medical psychology from the University of Oregon Medical School in 1973. He has been a diplomat of the American Board of Toxicology since 1982. Utah's Health: An Annual Review 1996 23 |
