Traffic is one of the major contributors to air pollution in urban areas; the dynamic mixture of gases and particles that results from vehicle exhaust and noncombustion emissions such as road and tire wear is known as traffic-related air pollution (TRAP). (1) The impact of TRAP exposure on human health has been the subject of epidemiological studies for two decades, but the mechanisms by which TRAP-associated particulate matter (PM) alters heart and lung function remain to be elucidated. In a recent pilot study reported in Environmental Health Perspectives, investigators sought to address this issue using a real-world model of TRAP exposure in rats. (2)
Worldwide, ambient air pollution is estimated to cause (3). (8) million premature deaths per year due to cardiovascular and respiratory diseases. (3,4) Several studies have reported an association between acute exposure to highly concentrated PM and development of cardiopulmonary dysfunction in humans and animals. (5,6,7,8,9)
Tunnel traffic has been used before to characterize single or well-defined mixtures of TRAP pollutants as well as associated health effects in humans and animals. (5,6,7,8,10) The new study, in contrast, examined health effects of chronic exposure to environmentally relevant doses of real-world TRAP. The animals' average exposures to fine PM roughly approximated the primary National Ambient Air Quality Standard of 12 [micro]g/[m.sup.3] per day per year set by the U.S. Environmental Protection Agency (EPA). (11)
David Diaz-Sanchez, director of the Public Health and Integrated Toxicology Division at the EPA Center for Public Health and Environmental Assessment, says the inclusion of both males and females is another unique feature of this study. "Some epidemiological studies have...