Exposure to air pollution and prevalence of metabolic syndrome: A nationwide study in China from 2011 to 2015

Evidence concerning the influence of air pollution on metabolic syndrome (MetS) is still limited. We aimed to investigate whether sustained exposure to air pollutants are associated with increased prevalence of MetS and its individual components.We conducted a cross-sectional study comprised of 14,097 individuals participated in the first or third survey of the CHARLS. The personal cumulative (3-year averaged) exposure concentrations of nitrogen dioxide (NO2), particulate matter (PM) with a diameter of 1.0 μm or less (PM1), PM with a diameter of 10 μm or less (PM10) and PM with a diameter of 2.5 μm or less (PM2.5) were estimated using a spatiotemporal random forest model at 0.1° × 0.1° spatial resolution based on residential address of each participant provided. We utilized logistic regression models to estimate the associations of the four air pollutants with the prevalence of MetS and its individual components, and performed interaction analyses to evaluate potential effect modifications by gender, health status, age and drinking status.Sustained exposure to air pollutants is associated with increased prevalence of MetS. For every 10 μg/m3 increase in NO2, PM1, PM10 and PM2.5, the adjusted odds ratio (OR) of MetS was 2.276 (95 % CI: 2.148, 2.412), 1.207 (95 % CI: 1.155, 1.263), 1.027 (95 % CI: 1.006, 1.048) and 1.027 (95 % CI: 0.989, 1.066), respectively. For MetS components, we observed significant associations between NO2, PM1, PM10 and central obesity, high blood pressure, elevated fasting glucose and low high-density lipoprotein cholesterol. For example, the adjusted OR of low high-density lipoprotein cholesterol for every 10 μg/m3 increase in NO2 was 1.855 (95 % CI: 1.764, 1.952). We also identified that age could significantly modified the association between NO2 and prevalence of MetS.Chinese adults sustained exposure to higher concentrations of air pollutants are associated with increased prevalence of MetS and its components.