We hypothesized that there is an interaction between air pollution exposure and genetic variants in the GST genes on risk of acute myocardial infarction (AMI) and thus we aimed to investigate, in a population-based study, a) the association of long-term traffic-related air pollution exposure with risk of acute myocardial infarction (AMI) and hypertension, b) the associations of genetic variants in GSTP1, GSTCD and GSTT1 with risk of AMI and hypertension, and c) if these genetic variants modify the associations between air pollution exposure and the two outcomes. The gene discussed is GSTP1; the disease is acute myocardial infarction.