Pollution May Trigger Heart Attacks

Acute myocardial infarction (MI) is triggered by various factors, with studies associating the onset with physical exertion, stressful events, heavy meals, and air pollution. Tim Nawrot, from Hasselt University (Belgium), and colleagues reviewed 36 published studies containing data on 13 potential MI triggers.  When both the odds ratios and the prevalence of exposure to each trigger were considered, the highest population attributable fraction was associated with traffic exposure (7.4%), followed by physical exertion (6.2%), alcohol (5%), coffee (5%), a difference of 30 micrograms/m3 in air pollution (4.8%), negative emotions (3.9%), anger (3.1%), a heavy meal (2.7%), positive emotions (2.4%), sexual activity (2.2%), cocaine use (0.9%), marijuana smoking (0.8%), and respiratory infections (0.6%).  The researchers calculate that reducing levels of particulate matter by 30 micrograms/m3 would potentially prevent or delay 4.8% of nonfatal MIs.  Emphasizing that: “air pollution is an important trigger of myocardial infarction,” the researchers submit that: “our work shows that ever-present small risks might have considerable public health relevance.”