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

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.

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 (PM₁₀) 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.

Exposure to PM₁₀ 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 PM₁₀ (- 0.07; 95% CI: - 0.13, - 0.09). Associations of PM_2.5 and PM₁₀ with FMD were somewhat stronger in men than in women, particularly for PM₁₀.

Using location-specific moving-average air pollution exposure estimates, we have shown that 12-month moving-average estimates of PM_2.5 and PM₁₀ exposure are associated with impaired endothelial function in a rural population.