Long-term exposure to particulate air pollution and brachial artery flow-mediated dilation in the Old Order Amish

BACKGROUND: Atmospheric particulate matter (PM) has been associated with endothelial dysfunction, an early marker of cardiovascular risk. Our aim was to extend this research to a genetically homogenous, geographically stable rural population using location-specific moving-average air pollution exposure estimates indexed to the date of endothelial function measurement. METHODS: We measured endothelial function using brachial artery flow-mediated dilation (FMD) in 615 community-dwelling healthy Amish participants. Exposures to PM < 2.5 μm (PM(2.5)) and PM < 10 μm (PM(10)) were estimated at participants’ residential addresses using previously developed geographic information system-based spatio-temporal models and normalized. Associations between PM exposures and FMD were evaluated using linear mixed-effects regression models, and polynomial distributed lag (PDL) models followed by Bayesian model averaging (BMA) were used to assess response to delayed effects occurring across multiple months. RESULTS: Exposure to PM(10) was consistently inversely associated with FMD, with the strongest (most negative) association for a 12-month moving average (− 0.09; 95% CI: − 0.15, − 0.03). Associations with PM(2.5) were also strongest for a 12-month moving average but were weaker than for PM(10) (− 0.07; 95% CI: − 0.13, − 0.09). Associations of PM(2.5) and PM(10) with FMD were somewhat stronger in men than in women, particularly for PM(10). CONCLUSIONS: Using location-specific moving-average air pollution exposure estimates, we have shown that 12-month moving-average estimates of PM(2.5) and PM(10) exposure are associated with impaired endothelial function in a rural population.