Association of PM _2.5 Reduction with Improved Kidney Function: A Nationwide Quasiexperiment among Chinese Adults

Background. Increasing evidence from human studies has revealed the adverse impact of ambient fine particles (PM _2.5) on health outcomes related to metabolic disorders and distant organs. Whether exposure to ambient PM _2.5 leads to kidney impairment remains unclear. The rapid air quality improvement driven by the clean air actions in China since 2013 provides an opportunity for a quasiexperiment to investigate the beneficial effect of PM _2.5 reduction on kidney function.Methods. Based on two repeated nationwide surveys of the same population of 5115 adults in 2011 and 2015, we conducted a difference-in-difference study. Variations in long-term exposure to ambient PM _2.5 were associated with changes in kidney function biomarkers, including estimated glomerular filtration rate by serum creatinine (GFR _scr) or cystatin C (GFR _cys), blood urea nitrogen (BUN), and uric acid (UA).Results. For a 10  μg/m ³ reduction in PM _2.5, a significant improvement was observed for multiple kidney functional biomarkers, including GFR _scr, BUN and UA, with a change of 0.42 (95% confidence interval [CI]: 0.06, 0.78) mL/min/1.73m ², -0.38 (-0.64, -0.12) mg/dL, and -0.06 (-0.12, -0.00) mg/dL, respectively. A lower socioeconomic status, indicated by rural residence or low educational level, enhanced the adverse effect of PM _2.5 on kidney function.Conclusions. These results support a significant nephrotoxicity of PM _2.5 based on multiple serum biomarkers and indicate a beneficial effect of improved air quality on kidney function.