Association of the components of ambient fine particulate matter (PM2.5) and chronic kidney disease prevalence in China

Previous research has implicated PM2.5 as a potential environmental risk factor for CKD, but little is known about the associations between its components and CKD. We conducted a nationwide cross-sectional study using the updated air pollution data in the nationwide population (N = 2,938,653). Using generalized additive models, we assessed the association between long-term exposure to PM2.5 and its components (i.e., black carbon [BC], organic matter [OM], nitrate [NO3-], ammonium [NH4+], sulfate [SO42-]), and CKD prevalence. The air pollution data was estimated using high-resolution and high-quality spatiotemporal datasets of ground-level air pollutants in China. Besides, we adopted a novel quantile-based g-computation approach to assess the effect of a mixture of PM2.5 constituents on CKD prevalence. The average concentration of PM2.5 was 78.67 +/- 22.5 mu g/m(3), which far exceeded WHO AQG. In the fully adjusted generalized additive model, at a 10 km x 10 km spatial resolution, the ORs per IQR increase in previous 1-year average PM2.5 exposures was 1.380 (95%CI: 1.345-1.415), for NH4+ was 1.094 (95%CI: 1.062-1.126), for BC was 1.604 (95%CI: 1.563-1.646), for NO3- was 1.094 (95%CI: 1.060-1.130), for SO42- was 1.239 (95%CI: 1.208-1.272), and for the OM was 1.387 (95%CI: 1.354-1.421), respectively. Subgroup analysis showed females, younger, and healthier were more vulnerable to this effect. In the further exploration of the joint effect of PM2.5 compositions (OR 1.234 [95%CI 1.222-1.246]) per quartile increase in all 5 PM2.5 components, we found that PM2.5SO42- contributed the most. These findings provide important evidence for the positive relationship between long-term exposure to PM2.5 and its chemical constituents and CKD prevalence in a Chinese health check-up population, and identified PM2.5SO42- has the highest contribution to this relationship. This study provides clinical and public health guidance for reducing specific air particle exposure for those at risk of CKD.