A rapidly growing body of epidemiological data has shown statistically significant associations between the concentrations of particles in the ambient air and rates of mortality and morbidity in populations exposed to concentrations below current USEPA standards and WHO-EURO air quality guidelines. When other known risk factors have been taken into account in regression analyses, it has been possible to show that daily changes of ambient particulate matter (PM) are associated with: 1) changes in daily mortality; 2) hospital admissions for respiratory diseases; 3) emergency room visits for respiratory diseases; 4) respiratory symptoms; and 5) lung function. For these various responses, there is sometimes a lag or one to a few days between exposure and response.Differences in long-term average levels of PM pollution have been associated with differences in: 1) annual mortality rates; 2) the prevalence of chronic disease and symptoms; 3) lost time from work or school; and 4) reduced lung function baselines. When multiple regressions are performed which include pollutant vapors as well as PM, the PM variable tends to be most influential. The only exceptions appear to be hospital admissions and symptoms, where ozone (O3) is sometimes as, or more, influential on the regressions than PM.Despite the consistency and coherence of these findings in human populations, there has been a reluctance by many to accept the associations as causal in the absence of more positive findings in controlled inhalation exposure studies in humans and laboratory animals. Only one PM component, i.e., hydrogen ion (H+) and one other ambient air pollutant, i.e., ozone (O3), have produced any comparable responses at peak ambient concentrations.This paper reviews the available epidemiologic evidence for PM-associated health effects and possible causes for such effects.
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- The Challenge of the Epidemiologic Evidence for Excess Mortality and Morbidity Associated with Atmospheric Aerosols
Ph.D. Morton Lippmann
- Springer Netherlands
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