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Research Programs: Particulate Matter (PM) Health Effects
Research Areas: Combined Effects
PM Health Effects
How can the effects of PM be disentangled from the effects of other pollutants?
Under the Clean Air Act, air quality standards are set for certain individual pollutants. However, PM coexists with other air pollutants; and a key uncertainty in PM-related health-effects research is the relative degree to which PM versus other pollutants is responsible for inducing ill effects.
A large epidemiological study, the National Morbidity, Mortality, and Air Pollution Study, examined data from 20 U.S. cities and found that, although exposure to higher levels of ambient PM (i.e., PM10) was associated with increases in daily mortality rates, this association was not confounded by the presence of gaseous co-pollutants1. Another analysis of data from 10 U.S. cities supported this finding and showed that there was no relationship between mortality attributable to PM10 and the presence of the co-pollutants ozone (O3), carbon monoxide (CO), or sulfur dioxide (SO2)2.
Additional studies are currently underway to differentiate the effects of PM from those of other stressors because reducing the uncertainty in scientists' understanding of the primary causes of adverse effects will assist EPA in setting air quality standards that protect human health.
