ABSTRACT
Over the past decade, numerous epidemiological studies have shown con-
sistent associations between increases in the levels of ambient particulate
matter (PM) and increases in human morbidity and mortality (1-7).
Furthermore, the evidence suggests that both the cardiovascular and pul-
monary systems may be primary targets of these toxic agents. However, despite intensive research efforts, neither the specific constituents of PM
responsible for these effects nor their mechanisms of action are well
understood.