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 (PM_2.5), 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 PM_2.5, 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.