The overall objective of this work was to better elucidate the toxic and inflammatory potential of urban and rural PM from the Central Valley on a suite of pulmonary, vascular and systemic endpoints in a mouse model. Specifically, mice received one intratrachael aspiration exposure to PM2.5, and effects were evaluated at post-exposure times of 1, 2 and 4 days to explore the temporal nature of different biological responses. PM2.5 samples were collected in a rural part of Davis that is surrounded by agricultural land and an urban part of downtown Sacramento near a major freeway interchange in order to obtain a comparison between the health effects elicited by PM that has different source mixtures. Sufficient PM was collected during a single winter collection campaign to allow animal exposures and chemical analysis using the same PM sampling filter. The results demonstrate (1) that the method of extraction of PM from the filter or impactor substrate has a substantial effect on the health effects elicited and the dose-response relationship; (2) some of the endpoints, especially the pulmonary ones, responded acutely to the PM, at 1 or 2 days post administration while other endpoints, especially systemic ones, responded at longer lag times, in agreement with epidemiological studies on cardiovascular responses to PM. The results have implications for design of future research studies, and help to explain some of the inconsistencies noted in previously published research.