Long-term air pollution exposure and decreased kidney function: A longitudinal cohort study in Bangkok Metropolitan Region, Thailand from 2002 to 2012

Background: Kidney dysfunction is considered a cardiovascular risk factor. However, few longitudinal studies have examined the effects of air pollution on kidney function. We evaluated associations between long-term air pollution exposure and estimated glomerular filtration rate (eGFR) using data from a cohort of the Electricity Generating Authority of Thailand (EGAT) study in Bangkok Metropolitan Region, Thailand. Methods: This longitudinal study included 1839 subjects (aged 52–71 years in 2002) from the EGAT1 cohort study during 2002–2012. eGFR, based on creatinine, was measured in 2002, 2007, and 2012. Annual mean concentrations of air pollutants (i.e., particulate matter with an aerodynamic diameter ≤10 μm (PM₁₀), ozone (O₃), nitrogen dioxide (NO₂), sulfur dioxide (SO₂), and carbon monoxide (CO)) prior to a measurement of creatinine were assessed with the ordinary kriging method. Mixed-effect linear regression models were used to assess associations between air pollutants and eGFR, while controlling for potential covariates. eGFR values are expressed as percent change per interquartile range (IQR) increments of each pollutant. Results: Lower eGFR was associated with higher concentrations of PM₁₀ (−1.99%, 95% confidence interval (CI): −3.33, −0.63), SO₂ (−4.89%, 95%CI: −6.69, −3.07), and CO (−0.97%, 95%CI: −1.96, 0.03). However, after adjusting for temperature, relative humidity, PM₁₀, and SO₂, no significant association was observed between CO and eGFR. Conclusions: Our findings support the hypothesis that long-term exposure to high concentrations of PM₁₀ and SO₂ is associated with the progression of kidney dysfunction in subjects of the EGAT cohort study.