21.09.11
Pollution increases heart attack risk
High pollution levels have been linked to an increased risk of heart attack, according to research published on bmj.com. Exposure to pollution can lead to increased risk for up to six hours afterward, it was found.
Researchers looked at the effects of hourly differences in air pollution on the risk of myocardial infarction through a case cross-over analysis of the database. They found that although risk of a heart attack increases after exposure to pollution, this was often categorised as ‘short-term displacement’, which means it would have occurred anyway, and was only brought forward by a few hours.
Krishnan Bhaskaran, an epidemiologist from the London School of Hygiene and Tropical Medicine, reviewed 79,288 heart attack cases from 2003 to 2006 and exposure, by the hour, to pollution levels.
The authors used the UK National Air Quality Archive to investigate the levels of specific pollutants in the atmosphere. These included pollutant particles, carbon monoxide, nitrogen dioxide, sulphur dioxide and ozone.
Given the authors found no net increase in heart attack risk over a broader timescale, they argue that there may be “limited potential for reducing the overall burden of myocardial infarction through reductions in pollution alone, but that should not undermine calls for action on air pollution, which has well established associations with broader health outcomes including overall, respiratory and cardiovascular mortality.”
Professor Richard Edwards and Dr Simon Hales from the University of Otago in New Zealand suggest in an accompanying editorial that these results may be due to imprecise measurements or inadequate statistical power of the study.
They conclude: “Given other evidence that exposure to air pollution increases overall mortality and morbidity, the case for stringent controls on pollutant levels remains strong”
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