IS THE ASSOCIATION OF AIR POLLUTION WITH INCIDENT CORONARY HEART DISEASE OR ALL CAUSE MORTALITY MODIFIED BY A HEALTHY LIFESTYLE?

Abstract

Background and Aims:Chronic exposures to particulate matter (PM) have been associated with increased morbidity and mortality. Few studies, however, have been able to examine the impacts of a healthy lifestyle on these associations. Methods:Monthly PM10 levels 1988-2006 were assigned to the residential address history of 101,307 members of the all-female Nurses’ Health Study and were used to calculate time-varying average exposure in the previous 12 months. Information on confounders and diet and physical activity was available from mailed questionnaires. Effect modification of the association of PM10 with risk of incident coronary heart disease (CHD) and all-cause mortality by diet, alcohol consumption, and physical activity was assessed in stratified Cox proportional hazards models. All models were adjusted for calendar month, season, current age, region, family history, high cholesterol or high blood pressure, BMI, diabetes, cigarette smoking, median census tract income and home value. . Results:Each 10 µg/m3 increase in 12 month average PM10 was associated with an all-cause hazard ratio (HR) of 1.07 (95%CI: 1.04-1.11) and an incident CHD HR=1.04 (95%CI: 0.97-1.12). We observed suggestions of effect modification of the all-cause mortality associations by total antioxidant intake and physical activity. Similar patterns were seen for incident CHD with additional effect modification by the prudent diet pattern, fruit consumption, and alcohol consumption. Overall, increasing consumption of healthy foods was associated with a lower risk per unit increase of PM10, while increasing physical activity levels were associated with higher risks. Conclusions:These results suggest that individuals with moderate alcohol consumption and increased consumption of healthy foods may be at a lower risk of incident CHD and all-cause mortality per 10 µg/m3 increase in PM10. Individuals with higher levels of physical activity may be at a higher risk, possibly due to additional time outdoors.