Five-year exposure to PM2.5 and ozone and subclinical atherosclerosis in late midlife women: The Study of Women's Health Across the Nation.

Abstract

Effects of more than one-year exposure to air pollution on atherosclerosis is seldom studied. This paper aims to examine the association between five-year exposure to particulate matter ≤2.5 μm (PM2.5), ozone (O3) and atherosclerosis observed about seven years later in late midlife women. This study was conducted among 1188 women of the Study of Women's Health Across the Nation (SWAN) from five sites, Detroit, MI; Oakland, CA; Pittsburgh, PA; Chicago, IL; and Newark, NJ, with available data on both air pollutant exposure and carotid ultrasound scans. Five-year mean annualized exposure levels of two air pollutants, PM2.5 and ozone (O3), were collected during 5 SWAN visits (1999-2005) from monitors 20 km within the participant's residential address. Linear regression models were used to estimate the association of prior five-year mean annualized exposure to PM2.5 and O3 with common carotid intima-media thickness (cIMT) and inter-adventitial diameter (IAD) examined approximately seven years later (2009-2013). Logistic and multinomial logistic regressions were applied to assess the associations of air pollutants with plaque presence and plaque index, respectively. At time of carotid ultrasound scan, women were on average 59.6 (±2.7) years old and a majority was postmenopausal (88.4%). The women were White (48.4%), Black (31.2%), Chinese (13.3%) and Hispanic (7.1%). A 1 μg/m3 higher 5-year mean annualized exposure to PM2.5 was associated with an 8.0 μm (95% CI: 1.0-15.1) greater maximum cIMT at a later mid-life, adjusting for cardiovascular disease risk factors; but was only related to IAD after adjusting for site. No association was found between either pollutant and plaque presence or plaque index. Long-term exposure to PM2.5 may contribute to elevated risk of atherosclerosis in the post-menopausal period.