Abstract 1183: Vascular Responses to Short and Long-term Ambient Air Pollution: The Multi-Ethnic Study of Atherosclerosis and Air Pollution
Objective: Both short-term and long-term increases in particulate air pollution levels (PM) have been associated with cardiovascular disease events; the mechanism is uncertain. Experimental and time-series studies have linked short-term PM to vasoconstriction and decreased flow-mediated dilation (FMD) of the brachial artery, respectively; long-term PM effects on vascular function have not been assessed. We hypothesized that increased short and long-term residential concentrations of fine particulate matter (PM2.5) would be associated with increased vascular tone and lower FMD.
Methods: We evaluated brachial artery ultrasound data from the Multi-Ethnic Study of Atherosclerosis (MESA) in participants, free of cardiovascular disease, age 45– 84 years, and examined in 2000 –2001. Baseline brachial artery diameter (BAD) and FMD were assessed: BAD as cross-sectional measure of vascular tone, and FMD for NO-mediated endothelial dysfunction. Short and long-term PM exposures were examined independently and jointly. Multivariate linear regression models examined associations between vascular measurements and long-term exposure to PM using estimated annual average PM2.5 concentrations at the home of each participant. Short-term associations were tested using the city-wide average concentration the day before examination. Models adjusted for age, gender, body surface area, ethnicity, income, education, season, temperature, coronary risk factors, exercise, medication use, and sonographer.
Results: Complete data was analyzed from 3,501 participants from five states. Long-term PM2.5 concentrations were negatively associated with both BAD and FMD. Each 10 μg/m3 increase in annual average PM2.5 was associated with a 0.20 mm decrement in BAD (95% CI: 0.004 to 0.41mm) and a 0.6% decrement in FMD (95% CI: 0.22 to 1.52%). Higher levels of daily PM2.5 were negatively associated with BAD, but not with FMD. Each 10 μg/m3 increase in daily PM2.5 was associated with a 0.03 mm decrease in BAD (95% CI: −0.003 to −0.05mm) and a 0.06% decrease in FMD (95% CI: −0.004 to 0.16%).
Conclusions: Short and long-term PM exposure are each associated with increased vasomotor tone. Long-term PM exposure is associated with deleterious effects on endothelial function.