Association between ambient air pollution and renal function indicators: A comprehensive systematic review and meta-analysis

Ambient air pollution is an emerging environmental risk factor for chronic kidney disease (CKD). Recognizing that changes in renal function indicators are critical markers for diagnosing and grading CKD and other kidney diseases, this meta-analysis aims to assess the associations of ambient air pollution with key renal function indicators. A comprehensive search up to September 27, 2024, was conducted across four databases (i.e., PubMed, Web of Science, Scopus, and Embase). Eligible studies were required to report the associations of ambient particulate matter (PM₁, PM_2.5, PM₁₀), nitrogen dioxide (NO₂), ozone (O₃), sulfur dioxide (SO₂), carbon monoxide (CO) with key renal function indicators (including eGFR, estimated glomerular filtration rate; SCr, serum creatinine; BUN, blood urea nitrogen; UA, uric acid; CysC, cystatin C) and to provide quantitative estimates of these associations. The primary meta-analyses were conducted involving 32 studies with adults (n = 3,022,895) as participants. Long-term PM_2.5, PM₁₀, and NO₂ exposures were linked to decreased eGFR, with pooled percent changes of -0.90 % (95 %CI: -1.71 %, -0.08 %), -1.05 % (95 %CI: -1.67 %, -0.42 %), and -0.43 % (95 %CI: -0.78 %, -0.08 %) every 10 μg/m³ increase in these air pollutants, respectively. Meanwhile, long-term PM_2.5 exposure (per 10 μg/m³) was also linked to elevated SCr (0.87 %, 95 %CI: 0.83 %, 0.92 %) and UA (1.07 %, 95 %CI: 0.31 %, 1.84 %). Furthermore, short-term PM_2.5 exposure (per 10 μg/m³) was linked to lower eGFR (-0.57 %, 95 %CI: -1.03 %, -0.10 %) and higher BUN (2.17 %, 95 %CI: 1.08 %, 3.28 %). Our study highlights the potential detrimental impacts of ambient air pollution on kidney function.