Leukocyte traits and exposure to ambient particulate matter air pollution in the women’s health initiative and atherosclerosis risk in communities study

Abstract

BACKGROUND: Inflammatory effects of ambient particulate matter (PM) air pollution exposures may underlie PM-related increases in cardiovascular disease risk and mortality, although evidence of PM-associated leukocytosis is inconsistent and largely based on small, cross-sectional, and/or unrepresentative study populations. OBJECTIVES: Our objective was to estimate PM–leukocyte associations among U.S. women and men in the Women’s Health Initiative and Atherosclerosis Risk in Communities study (n = 165,675). METHODS: We based the PM–leukocyte estimations on up to four study visits per participant, at which peripheral blood leukocytes and geocoded address-specific concentrations of PM ≤ 10, ≤2:5, and 2:5–10 lm in diameter (PM10, PM2:5, and PM2:5–10, respectively) were available. We multiply imputed missing data using chained equations and estimated PM–leukocyte count associations over daily to yearly PM exposure averaging periods using center-specific, linear, mixed, longitudinal models weighted for attrition and adjusted for sociodemographic, behavioral, meteorological, and geographic covariates. In a subset of participants with available data (n = 8,457), we also estimated PM–leukocyte proportion associations in compositional data analyses. RESULTS: We found a 12 cells=lL (95% confidence interval: −9, 33) higher leukocyte count, a 1.2% (0.6%, 1.8%) higher granulocyte proportion, and a −1:1% (−1:9%, −0:3%) lower CD8+ T-cell proportion per 10-lg=m3 increase in 1-month mean PM2:5. However, shorter-duration PM10 exposures were inversely and only modestly associated with leukocyte count. DISCUSSION: The PM2:5 –leukocyte estimates, albeit imprecise, suggest that among racially, ethnically, and environmentally diverse U.S. populations, sustained, ambient exposure to fine PM may induce subclinical, but epidemiologically important, inflammatory effects. https://doi.org/10.1289/EHP5360