ABSTRACT
Introduction: Air pollution is a novel environmental risk factor for chronic kidney disease (CKD). Air quality improved during COVID-19 lockdowns; however, the effects of these lockdowns on PM2.5 concentrations and renal function remain unclear. Methods: We conducted a retrospective cohort study to compare air pollution and estimated glomerular filtration rate (eGFR) decline in patients with stage 5 CKD between a year-long period of lockdown (2020; n = 724) and a similar period before lockdown (2019, n = 758). Results: Compared with 2019, a 17.5% reduction in the average PM2.5 concentration (from 17.36% to 14.32%; P < 0.001) and a 45.1% reduction (from 20.56% to 11.25%; P < 0.001) in cumulative days with PM2.5 concentration >35 µg/m3 were noted in 2020. Moreover, a 93% reduction in PM2.5 air quality index >150 per station-day (from 0.43% to 0.03%) was observed in 2020. From 2019 to 2020, the yearly incidence of eGFR decline ≥5 mL/min/1.73 m2 decreased by 33.7% (24.6% vs 16.3%; P < 0.001). Similarly, the proportion of patients who started undergoing regular dialysis also decreased by 32.7% in 2020 (from 20.8% to 14.0%; P = 0.001). Conclusion: Our findings suggest that fewer events of renal function decline during the COVID-19 pandemic may be associated with a decline in PM2.5 concentrations, supporting the global strategy of reducing air pollution to prevent CKD progression.