Combined Effects of Physical Activity and Air Pollution on Cardiovascular Disease: A Population-Based Study

BACKGROUND: Physical activity (PA), particularly outdoor PA, may have dual effects on cardiovascular disease (CVD) risk: health benefits of exercise and potential harmful effects attributable to increased exposure to air pollution. We examined the combined effects of PA and air pollution on CVD. METHODS AND RESULTS: Sampling from a nationwide cohort study of the Korean National Health Insurance Service, we examined 189 771 adults aged >= 40 years who underwent health examination between 2009 and 2010. PA was measured with a questionnaire on the weekly frequency and intensity. Ambient levels of particulate matter 10, 2.5 (PM10, PM2.5) were estimated by the residency of participants. We conducted Cox proportional hazard regression analysis to estimate the relationship between CVD risk and combined effects of PA and air pollution. Subjects with moderate to vigorous PA >5 times/week and high PM10 exposure had lower risk of CVD (adjusted hazard ratio [aHR], 0.73; 95% Cl, 0.62-0.87), coronary heart disease (aHR, 0.76; 95% Cl, 0.59-0.98), and stroke (aHR, 0.70; 95% Cl, 0.56-0.88). The inverse association between PA and CVD risk was consistent when the analysis was performed for subjects with low/moderate PM10 exposure. When using PM2.5 data, the results were also consistent. CONCLUSIONS: Moderate to vigorous PA appeared to reduce the risk of CVD within groups of both high and low PM10 or PM2.5 levels. Further studies are needed to validate whether the health benefits of PA outweigh the potential harmful effects resulting from increased exposure to air pollution during PA.