ACE and myocardial infarction: We observed no significant or consistent evidence of effect modification of associations between ST depression and primary air pollutant exposures by actigraph-measured physical activity, heart rate, sex, history of myocardial infarction, or medication use (statins, β-adrenergic receptor blockers, calcium channel blockers, angiotensin I-converting enzyme inhibitors/angiotensin II receptor antagonists) (data not shown).