... potential benefits of reducing the risk factor by a specified amount. 2. A determination of the size of the population groups exposed to PM10 and PM2.5, and the type of health effect of interest. ... effects, however, PM2.5 and PM10 have been selected because of the relative wealth of epidemiological evidence and the existence of monitors or model-based estimates of PM in many countries. ... cardiovascular and respiratory disease, emergency room and physician office visits, asthma exacerbation, respiratory symptoms, loss of schooling, restrictions in activity, and acute and chronic...