Residential Exposure to PM 2.5 and Ozone and Progression of Subclinical Atherosclerosis Among Women Transitioning Through Menopause: The Study of Women's Health Across the Nation.

Objective: This article aims to examine the association between long-term ambient air pollution and progression of subclinical atherosclerosis with 2-year follow-up among midlife women from the Study of Women's Health Across the Nation (SWAN). Materials and Methods: Carotid duplex ultrasonography was performed in participants from a SWAN ancillary study carried out at the Pittsburgh and Chicago sites. Mean and maximum carotid intima-media thickness (CIMT) and plaque burden were assessed throughout the common, bulb, and internal carotid artery. The yearly mean exposure to PM _2.5 (particulate matter) and ozone was generated based on monitors within 20 km of the participants' home. The effect of air pollutants during follow-up on progression of CIMT was estimated using linear mixed-effects models, and the effect on progression of plaque presence and plaque index, a measure of extent of plaque, was evaluated using logistic regression. Results: This study included 417 (257 White and 160 Black) women with a mean age of 51 years at baseline. A 1 μg/m ³ higher yearly mean exposure to PM _2.5 during follow-up was associated with a 4.28 (95% confidence interval [CI]: 0.02-8.54) μm/year increase in maximum CIMT, after adjusting for socioeconomic and traditional cardiovascular disease (CVD) risk factors. Exposure to PM _2.5 contributed to a 30% (95% CI: 3%-65%) higher odds of plaque index progression adjusting for socioeconomic factors only. Conclusions: PM _2.5 independently contributed to progression of subclinical atherosclerosis, among women transitioning through menopause, a time of increasing CVD risk. Yet no significant associations between ozone and subclinical atherosclerosis were observed.