Long-term exposure to ambient air pollutant mixture and metabolic obesity phenotypes: Results from a nationwide Korean study (2007-2019)

Abstract

BackgroundAcademic interest in the health impacts of air pollutant mixtures has increased in past years. Studies indicated that air pollutants exposure is linked to obesity and metabolic syndrome.ObjectiveThis study aimed to explore the association of air pollutant mixture with metabolic obesity phenotypes.MethodsA nationwide sample of 68,675 adults was analyzed in our cross-sectional study. Participants were linked to modeled air pollution data from 2007 to 2019. The concentrations of PM2.5-10, PM2.5, NO2, CO, SO2, and O3 were estimated for 2-year moving averages. Metabolic obesity phenotypes were classified into metabolically healthy obesity (MHO; body mass index [BMI] >= 25 kg/m2; without metabolic abnormality) and metabolically unhealthy obesity (MUO; BMI >= 25 kg/m2; with metabolic abnormality). The quantile g-computation was used to determine the association of air pollutant mixture with MHO and MOU.ResultsIn total, 46,061 individuals were classified as non-obese, 2724 individuals were classified as MHO, and 19,890 individuals were classified as MUO. In the quantile g-computation, one quartile increase in the concentration of air pollutant mixture was positively associated with MUO (OR [odds ratio]: 1.12, 95% CI [confidence interval]: 1.05-1.19) but not with MHO (OR: 1.00, 95% CI: 0.87-1.15). O3, CO, and PM2.5-10 accounted for 37.6%, 21.6%, and 21.3% of the positive association of air pollutant mixture with MUO, respectively.ImpactMounting evidence shows that outdoor air pollution is linked to obesity. We explored the association between long-term exposure to air pollutant mixture and metabolic obesity phenotypes. Obesity phenotypes were classified as metabolically healthy obesity (MHO) and metabolically unhealthy obesity (MUO). A mixture analysis showed that quartile increase in the concentration of the air pollutant mixture is associated with 1.12-fold increase in the odds of MUO, but not with MHO. Our novel findings suggest that long-term exposure to air pollutants may affect both metabolic abnormalities and obesity, contributing to a shift towards a metabolically unfavorable obesity profile.