Roberts, Steven2015-12-101352-2310http://hdl.handle.net/1885/68152Two critical issues for public health assessment and regulation of exposure to particulate matter air pollution (PM) are whether there is a threshold in the concentration-response relation between PM and mortality and whether there is mortality displacement. In this vein, a number of time-series studies have concluded that a linear relation without a threshold is appropriate for describing the concentration-response relation, and a number of other studies have concluded that the mortality effects of PM exposure cannot be attributed to mortality displacement alone. Using three-state (healthy, frail, dead) population models that incorporate actual time series data from Cook County, Illinois for the period 1987-2000, the author investigates the shape of the concentration-response relation between PM and mortality, as observable from time-series data, in the presence of mortality displacement. It is found that thresholds in the concentration-response relation can be masked, or hidden, by linear concentration-response relations if some of the effect of PM exposure is attributable to mortality displacement. This is an important finding that has implications for studies that have found a linear concentration-response relation appropriate, particularly given the markedly different implications for public health assessment and regulation of a linear versus threshold concentration-response relation.Keywords: Concentration-response; Critical issues; Displacement mask; Illinois; Linear relation; Mortality; Mortality displacement; Particulate Matter; Particulate matter air pollution; Population model; Public health; Time-series data; Air quality; Concentration ( Air pollution; Concentration-response; Harvesting; Mortality; Mortality displacement; Particulate matter; Time-series201110.1016/j.atmosenv.2011.04.0502016-02-24