A recent European study claims that air pollution is a major cause of heart attacks. Tim S. Nawrot, et al., “Public Health Importance of Triggers of Myocardial Infarction: A Comparative Risk Assessment,” The Lancet, February 24, 2011. Researchers combined data from 36 studies and estimated the risk of each trigger and the proportion of total heart attacks caused by each one in a given population. The study concluded that air pollution is an important trigger of myocardial infarction and is similar in magnitude to other well-accepted triggers, such as physical exertion, alcohol and coffee.