Association Between Short-Term Exposure to PM_2.5and PM₁₀and Mortality in Susceptible Subgroups: A Multisite Case-Crossover Analysis of Individual Effect Modifiers

We performed a multisite study to evaluate demographic and clinical conditions as potential modifiers of the particulate matter (PM)–mortality association. We selected 228,619 natural deaths of elderly persons (ages ≥65 years) that occurred in 12 Italian cities during the period 2006–2010. Individual data on causes of death, age, sex, location of death, and preexisting chronic and acute conditions from the previous 5 years’ hospitalizations were...