[Association between short-term ambient air pollution exposure and arterial stiffness and effect modification of obesity].

Objective: To assess the association between short-term ambient air pollution exposure and arterial stiffness and whether obesity modifies these associations. Methods: A cross-sectional study was conducted based on Fangshan family cohort in Beijing. The 24 hours average air pollutant levels on the day cohort participants took baseline survey were calculated as short-term air pollution. A generalized additive model (GAM) with Gaussian links was used to estimate changes in typical carotid artery intima-media thickness (CIMT), brachial-ankle pulse wave velocity (BAPWV), pulse pressure (PP) and ankle-branchial index (ABI) after short-term exposure to each air pollution (PM_2.5, PM₁₀, SO₂, NO₂, CO). The cross-product terms of each air pollution, body mass index (BMI), and waist-to-hip ratio were included in the GAM model to test the interaction. Further, they conducted a stratified analysis to test their effects on the relationship between short-term exposure to each air pollution and the arterial stiffness indicators. Results: A total of 4 211 individuals were included in the analysis. Individuals' age was (58.9±8.7) years, of which 2 268 (53.9%) were female. Several covariates, including sociodemographic factors, lifestyle behaviors, and history of drugs, were included in the analysis. The results of the GAM analysis showed that an increase in PM_2.5 (β=2.912×10^-4, 95%CI: 1.424×10^-4-4.400×10^-4, P<0.001), CO (β=0.027, 95%CI: 0.011-0.043, P<0.001), SO₂ (β=2.070×10^-3, 95%CI: 7.060×10^-4-3.430×10^-3, P=0.003), and NO₂ (β=3.650×10^-4, 95%CI: 2.340×10^-5-7.060×10^-4, P=0.036) were associated with an increase in CIMT, while an increase in PM₁₀ (β=0.018, 95%CI: 0.002-0.033, P=0.028) was associated with an increase in PP in the study population. Besides, the waist-to-hip ratio had an effect-modification on the correlation of short-term exposure of PM_2.5 (interaction P=0.015), NO₂ (interaction P=0.008), and CO (interaction P=0.044) with CIMT, and the correlation between short-term exposure of PM_2.5 (interaction P=0.002), NO₂ (interaction P=0.010), CO (interaction P=0.029), PM₁₀ (interaction P<0.001) with PP. The significant association between CIMT, PP, and air pollution concentrations was more visible in people with lower waist-to-hip ratios. Conclusions: Short-term ambient air pollution exposure was associated with arterial stiffness indicators, and there was an effect modification of waist-to-hip ratio on these associations, and lower waist-to-hip ratios may enhance the association between air pollution exposure and indicators.