Long-term Exposure to Traffic Pollution and Subclinical Atherosclerosis in African Americans: Results from the Jackson Heart Study

Abstract

Background: Long-term exposure to ambient air pollution may be associated with subclinical atherosclerosis, but few studies have evaluated long-term exposure to traffic-related pollution. Moreover, this hypothesis has not been previously evaluated in African Americans. Aims: We assessed the cross-sectional association between markers of long-term exposure to traffic pollution and carotid intima-media thickness (CIMT), a marker of subclinical atherosclerosis, in 4,995 African American adults in Jackson, MS. Methods: We calculated residential distance to the nearest major roadway and sum of road length within a radius from residence. Maximum CIMT was measured in the common carotid artery via B-mode ultrasonography. We used linear regression to estimate the percent difference in CIMT associated with residential proximity to major roadways, adjusting for age, sex, body mass index (BMI), smoking, alcohol consumption, individual- and neighborhood-level markers of socioeconomic status, residential food environment, and history of cardiovascular disease. Results: Participants were 63% female with a mean age of 54.9 (SD: ±12.8) years. CIMT was positively associated with age, sex, BMI, smoking, hypertension and hyperlipidemia. Living <50m, 50-200m, 200-400m,400-1000m (vs >1000m) from a major roadway was associated with a non-significant 3.2% (95% CI:-13.1%, 7.8%), 5.1% (-11.6%, 1.9%), 0.1% (-4.3%, 4.3%), 0.2% (-2.6%, 2.3%) decrease in CIMT after adjusting for potential confounders, respectively. No significant linear trends were observed (p=0.07). The results were not materially different when considering the log of distance to roadway as a linear continuous variable, the sum of road length as exposure or after additional adjustment for hypertension, diabetes and hyperlipidemia. Conclusions: Among African American participants in the Jackson Heart Study, we found no evidence of a cross-sectional association between markers of long-term exposure to traffic pollution and subclinical atherosclerosis as assessed by CIMT.