Associations between Short-term Changes in Air Pollution and Correlates of Arterial Stiffness: the VA Normative Aging Study

Abstract

Background: Few observational studies have evaluated changes in arterial stiffness after short-term exposure to air pollution. Aims: We investigated associations between short-term changes in air pollution and central augmentation index (AIx) and augmentation pressure (AP), correlates of arterial stiffness, in a cohort of elderly men in the Boston metropolitan area. Methods: This longitudinal analysis included 378 participants from the VA Normative Aging Study with up to two visits between 2007 and 2011. AIx (%) and AP (mmHg) were measured at each visit using radial artery applanation tonometry for pulse wave analysis, and modeled in a mixed effect regression as continuous functions of moving average (4h, 24h, 2 to 14 days) of air pollution exposures. All models were adjusted for age, body mass index, high density lipoprotein cholesterol level, education, race, alcohol consumption, smoking status, cumulative pack-years smoked, diabetes status, seasonality, day of week, and corresponding moving average of absolute temperature and relative humidity. Results: Statistically significant (p<0.05) positive associations were observed between exposure to sulfate (SO42-) and fine particles (PM2.5), and particle number counts (PNC), and AIx for several moving averages. Interquartile range increases in 2-day average SO42- (1.6 ?g/m3 increase) and PM2.5 (3.8 ?g/m3 increase), and 11-day average PNC (7,354 counts/cm3), were associated with 0.7% (95%CI: 0.1-1.2%), 0.9% (95%CI: 0.3-1.5%), and 2.6% (95%CI: 1.2-4.1%) higher AIx, respectively. Overall, the findings were very similar for AP. Conclusions: Short-term changes in air pollution were associated with correlates of arterial stiffness in this study sample of predominantly elderly white men. The findings support the hypothesis for the role of vascular function in the cardiovascular health effects of air pollution.