Health effects of concentrated ambient air particulate matter (CAPs) and its components.

We review literature that provides insights on health-related effects observed in laboratory-based inhalation studies in humans and laboratory animals using concentrated ambient air particulate matter (CAPs) in the fine, thoracic coarse, and ultrafine size ranges. The CAPs studies are highly informative on the health effects of ambient air particulate matter (PM) because they represent realistic PM exposure mixtures. When PM components are also analyzed and regressed against the effects, they can sometimes be used to identify influential individual components or source-related mixtures responsible for the effects. Such CAPs inhalation studies are analogous to epidemiological studies of human populations for which both health-related effects were observed and PM composition data were available for multi-pollutant regression analyses or source apportionment. Various acute and chronic health-related effects have occurred in short- and long-term CAPs inhalation studies in the cardiovascular, nervous, hepatic, and pulmonary systems, as well as changes in markers of the metabolic syndrome, and many correspond to effects associated with ambient air PM exposures in epidemiological studies. In addition, many CAPs studies have been conducted in coordination with in vitro studies that have identified biomarkers indicative of the underlying biological mechanisms that account for the responses.