Ambient PM1 air pollution and cardiovascular disease prevalence: Insights from the 33 Communities Chinese Health Study

Backgrounds: Evidence on the association between long-term exposure to particulate matter with aerodynamic diameter <= 2.5 mu m (PM2.5) and cardiovascular disease (CVD) is scarce in developing countries. Moreover, few studies assessed the role of the PM1 (<= 1.0 mu m) size fraction and CVD. We investigated the associations between PM1 and PM2.5 and CVD prevalence in Chinese adults. Methods: In 2009, we randomly recruited 24,845 adults at the age of 18-74 years from 33 communities in Northeastern China. CVD status was determined by self-report of doctor-diagnosed CVD. Three-year (2006-08) average concentrations of PM1 and PM2.5 were assigned using a satellite-based exposure. We used spatial Generalized Linear Mixed Models to evaluate the associations between air pollutants and CVD prevalence, adjusting for multiple covariates. Stratified and interaction analyses and sensitivity analyses were also performed. Results: A 10 mu g/m(3) increase in long-term exposure to ambient PM1 levels was associated a 12% higher odds for having CVD (OR = 1.12; 95% CI = 1.05-1.20). Compared to PM1, association between PM2.5 and CVD was lower (OR = 1.06; 95% CI = 1.01-1.11). No significant association was observed for PM1-2.5 (1-2.5 mu m) size fraction (OR = 0.98; 95% CI = 0.85-1.13). Stratified analyses showed greater effect estimates in men and the elder. Conclusions: Long-term PM1 exposure was positively related to CVD, especially in men and the elder. In addition, PM1 may play a greater role than PM2.5 in associations with CVD. Further longitudinal studies are warranted to confirm our findings.