Short-Term Exposure to Air Pollution and Arterial Stiffness

Introduction In prior studies, short-term air pollution exposure has been associated with augmentation index (AIx), a measure of peripheral wave reflection correlated with vascular stiffness. We hypothesized that short-term air pollution would be associated with AIx, but not measures primarily related to central arterial stiffness including carotid femoral pulse wave velocity (CFPWV), forward pulse pressure amplitude (FWA) and mean arterial pressure (MAP). Methods A total of 3188 participants living within 40km of the Harvard Supersite underwent arterial tonometry to assess CFPWV, FWA, MAP and AIx. We used hourly data on PM2.5, Black Carbon (BC), particle number (PN), sulfate (SO42-), and Nitrogen Oxides (NOx) to calculate 1, 3, 7 and 14 day moving averages. We took a descriptive approach and fit linear regression models adjusting for age, sex, body mass index, heart rate, smoking status, diabetes, lipids, cohort, education, income level, time trend, day of week, season, and ambient temperature. Results CFPWV, FWA and MAP were moderately correlated (Spearman r=0.52-62) but were only weakly correlated with AIx (r=0.13-0.28). Higher levels of PM2.5 and SO42- were associated with higher AIx for longer moving averages but not higher CFPWV, FWA or MAP (Figure). We observed unexpected associations between higher BC and NOx and lower CFPWV. Conclusions Short-term exposure to PM2.5 and SO42- was associated with higher AIx but not measures of central arterial stiffness. The associations between BC, NOx and lower CFPWV may reflect dynamic changes in CFPWV and require further study.