Joint impacts of air pollution and healthy lifestyles on kidney function decline: insights from a nationwide cohort study

Long-term exposure to ambient air pollution is a recognized environmental risk factor for chronic kidney disease (CKD), but its dynamic effects on kidney function remain incompletely understood. This nationwide longitudinal study included 5,306 participants from the China Health and Retirement Longitudinal Study (CHARLS) to examine associations between five major air pollutants (PM₁, PM_2.5, PM₁₀, NO₂, and O₃) and kidney function decline, measured by the annual slope of estimated glomerular filtration rate (eGFR). Air pollutant exposures were assessed both as continuous variables and dichotomized by median levels. Higher exposure to PM₁, PM_2.5, PM₁₀, and NO₂ was consistently associated with faster eGFR decline. In fully adjusted models, each 1 μg/m³ increase in PM_2.5 corresponded to a steeper decline in eGFR (<i>β</i> = -0.02; 95% CI: -0.03 to -0.02), while participants in high PM_2.5 areas had an annual decline of -0.51 mL/min/1.73 m² (95% CI: -0.72 to -0.31). O₃ showed a significant association only in binary models. Weighted quantile sum regression identified PM_2.5 and PM₁ as dominant contributors. A favorable lifestyle markedly mitigated pollution-related decline; under high PM₁ exposure, eGFR declined by -0.69 (95% CI: -1.06 to -0.33) in those with favorable lifestyles versus -2.20 (95% CI: -2.65 to -1.75) in those with unfavorable lifestyles. These findings were robust across multiple sensitivity analyses. These findings emphasize the adverse impact of long-term air pollution exposure on kidney function and suggest that healthy lifestyle behaviors may offer significant protective benefits.