Abstract

Background: Short-term fluctuations in air pollution have been associated with changes in both overall and cardiovascular mortality. We aimed to consider the effects of air pollution on myocardial infarction (MI) risk by systematically reviewing studies looking at this specific outcome.

Methods and results: We searched for studies of original data in which MI was a specific outcome and one or more of the following were exposures of interest: particulate matter (PM), black carbon/black smoke, ozone, carbon monoxide, nitrogen oxides, sulphur dioxide, and traffic exposure. We searched the databases MEDLINE, EMBASE, and TOXNET, as well as reference lists, and the websites of relevant public organisations. 26 studies were identified: 19 looked at the short-term effects of pollution on a daily timescale; the remaining 7 at longer term effects. A proportion of studies reported statistically significant detrimental effects of PM with diameter <2.5µm (3/5 studies, risk increase estimates ranging from 5-17% per 10µg/m3 increase), PM <10µm (3/10, 0.7-11% per 10µg/m3), CO (6/14, 2-4% per ppm), SO2 (6/13, effect estimates on varied scales), and NO2 (6/13, 1-9% per 10ppb). Increasing ozone levels were associated with a reduction in MI risk in 3/12 studies. We identified a number of differences between studies in terms of location, population and demographics, and study methodology that could have affected results.

Conclusions: There is some evidence that short-term fluctuations in air pollution affect risk of MI. However there is a need for further studies to clarify the nature of these effects and identify vulnerable populations and individuals.