My research project is a part of a larger program that aims to assess the low-dose effect of ambient air pollution on chronic disease mortality in Canada. The larger program has the following specific objectives: 1) Examine the shape of the association between long-term exposure to ambient concentrations of PM2.5 and cause-specific mortality in three large Canadian cohorts (i.e. the 1991, 1996, and 2001 Canadian Census, Health and Environment Cohort (CanCHEC)); and 2) Examine the sensitivity of the estimated shape of the concentration-mortality curve to various confounding adjustments and effect modifications. My research project focuses on Objective 2 in which we want to assess the degree of potential bias from missing lifestyle risk factors (e.g. smoking, alcohol use, and obesity) on the association between air pollution and cause-specific mortality using a method of indirect adjustment.