The impact of particulate matter air pollution (PM2.5) on atherosclerosis in modernizing China: a report from the CATHAY study.
BACKGROUND
Air pollution has been associated with an increase in cardiovascular diseases incidence. To evaluate whether air pollution can accelerate atherogenic processes, we assessed the effects of air pollution on important surrogate markers of atherosclerosis [brachial flow-mediated dilation (FMD) and carotid intima-media thickness (IMT)].


METHODS
A total of 1656 Han Chinese (mean age 46.0 + 11.2 years; male 47%) in Hong Kong, Macau, Pun Yu, Yu County and the 3-Gorges Territories (Yangtze River) were studied between 1996 and 2007 [Chinese Atherosclerosis in the Aged and Young Project (the CATHAY Study)]. Cardiovascular risk profiles were evaluated. Particulate matter with an aerodynamic diameter <2.5 µm (PM2.5) parameters were computed from satellite sensors. Brachial FMD and carotid IMT were measured by ultrasound.


RESULTS
Health parameters [age, gender, body mass index, waist : hip ratio (WHR) and glucose)] were similar in lowest and highest PM2.5 exposure tertiles, systolic and diastolic blood pressures and triglycerides were higher (P < 0.001) and low-density cholesterol (LDL-C) was lower in the top PM2.5 tertile (P < 0.001). Brachial FMD [7.84 ± 1.77, 95% confidence interval (CI) 7.59-8.10%, vs 8.50 ± 2.52, 95% CI 8.23-8.77%, P < 0.0001) was significantly lower and carotid IMT (0.68 ± 0.13 mm, 95% CI 0.67-0.69 mm vs 0.63 mm ± 0.15 mm 95% CI 0.62-0.64 mm; P < 0.0001) was significantly thicker in the top PM2.5 tertile compared with the lowest tertile. On multiple regression, FMD was inversely related to PM2.5 (beta = 0.134, P = 0.015) independent of gender, age and blood pressure (model R2 = 0.156, F-value = 7.6, P < 0.0001). Carotid IMT was significantly correlated with PM2.5 exposure (beta = 0.381, P < 0.0001) independent of age, location, gender, WHR, blood pressure and LDL-C (model R2 = 0.408, F-value = 51.4, P-value <0.0001).


CONCLUSIONS
Air pollution is strongly associated with markers of early atherosclerosis, suggesting a potential target for preventive intervention.
['Woo|K S|KS|0000-0002-5953-0386', 'Chook|P|P|', 'Hu|Y J|YJ|', 'Lao|X Q|XQ|', 'Lin|C Q|CQ|', 'Lee|Pwa|P|', 'Kwok|Cyt|C|', 'Wei|A N|AN|', 'Guo|D S|DS|', 'Yin|Y H|YH|', 'Lau|Kha|K|', 'Leung|K S|KS|', 'Leung|Y|Y|', 'Celermajer|D S|DS|']
D000328:Adult D000368:Aged D000397:Air Pollution D050197:Atherosclerosis D059168:Carotid Intima-Media Thickness D002681:China D006723:Hong Kong D006801:Humans D008297:Male D008875:Middle Aged D052638:Particulate Matter D012307:Risk Factors
air pollution (PM2.5) modernizing China Flow-mediated dilation carotid intima-media thickness