Other studies of humans and animals have shown associations between ambient PM and
heart rate control, arrhythmias, and abnormalities of cardiac depolarization as manifested by
ST segment depression. Although none of the ambientPMresults are specific toDPM,DPM
must be assumed to contribute some portion in lieu of better information on the PM species
causing the effects.
Studies in Humans Information from humans derives from several study designs. There is
indirect evidence from occupational and population-based epidemiologic studies linking
adverse cardiovascular outcomes to traffic emissions, evidence from panel studies where
smaller groups were monitored and physiologic observations were recorded and related to
environmental exposures, and direct evidence from laboratory studies involving
experimental exposures.