Previously, a number of studies have suggested associations between ischemic heart disease risk and both traffic noise and ambient air pollution.  Mette Sorensen, from the Danish Cancer Society (Denmark), and colleagues reviewed data from the Diet, Cancer, and Health cohort, a population-based study of Copenhagen residents, ages 50 to 64 years at the study’s start. The team included 50,614 people who were free from cancer and coronary artery disease at baseline. The researchers estimated traffic noise using the participants' home addresses and used estimated levels of nitrogen oxides as a measure of air pollution exposure. Through an average follow-up of 9.8 years, there were 1,600 first-ever myocardial infarctions (MIs; heart attacks) identified through national registries and medical records.  The team observed that MIs were more likely at higher levels of traffic noise exposure, whether the exposure was measured at the time of diagnosis, or averaged over the 5 years preceding the event.  When looking at fatal MIs, the unadjusted incidence rate ratio for every 10 decibel increase in traffic noise was 1.25.  The study authors conclude that: “Exposure to long-term residential road traffic noise was associated with a higher risk for [myocardial infarction], in a dose-dependent manner.”