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It is already clear that air pollution is associated with an increased risk of cardiovascular events such as heart attack, arrythmias, and even death. To investigate why, researchers from Europe did a controlled experiment on 20 men with stable coronary heart disease. The men exercised on a bicycle ergometer in clean air and in air containing diesel fumes at a concentration found in heavy traffic. As expected, the men had asymptomatic myocardial ischaemia during the exercise periods. But it was significantly worse when they were exposed to diesel. Six hours later, blood tests also showed a significant association between exercising in polluted air and impaired fibrinolysis. The researchers found no evidence of an effect on peripheral vasodilationvasodilation.
They used an idling Volvo to generate diesel pollution containing 300 µg/m3 of particulate matter, the component most consistently implicated in cardiovascular events. It now seems likely that these particles have proischaemic effects, which could help explain why even short term exposure to pollution has been linked to heart attack. A linked editorial (p 1147) suggests that people should exercise away from heavy traffic if possible.