Mid-Term Exposure to Air Pollution and Acute Kidney Injury Incidence: A 10-Year Study in Eastern Poland

Background/Objectives: Air pollution is associated with many adverse health consequences, including deteriorated kidney function. The aim of the research was to determine the association of medium-term exposure to air pollutants and hospitalizations due to acute kidney injury (AKI). Methods: The retrospective population-based study was conducted on the EP-PARTICLES cohort between 2011 and 2020 (80,000,000 person-years). We estimated municipality-specific associations between air pollution and AKI admissions using generalized additive models with Poisson regression. Results are reported as risk ratio in AKI admissions (RR) with corresponding 95% confidence intervals (95% CI). Results: During the 10-year study period, 47,467 AKI cases were reported (median age 77 years, IQR 68–84; 51.2% women). Mean concentrations of pollutants were 21.4 µg/m3 (SD 5.2) for particulate matter with a diameter of 2.5 μm or less (PM2.5), 7.5 µg/m3 (1.8) for nitrogen dioxide (NO2), and 1.8 ng/m3 (0.8) for benzo[a]pyrene (BaP). In mid-term exposure analyses (lag 0–30), each 10 µg/m3 increase in PM2.5, PM10, NO2 and CO, and each 1 µg/m3 increase in BaP, was associated with higher AKI risk, with the strongest effect observed for NO2 (RR 1.066, 95% CI 1.033–1.099). No association was found for SO2. Subgroup analyses showed consistent directions of association across sex and age groups, with NO2 remaining the most detrimental pollutant. Although statistical significance varied between pollutants, no significant effect modification by sex or age was observed (p > 0.05). Conclusions: Mid-term exposure to ambient air pollution is associated with an increased risk of AKI-related hospitalizations, with NO2 showing the strongest effects. These findings identify mid-term exposure as a relevant temporal window and support the role of air pollution as a modifiable risk factor for AKI.