Association between the Indoor Styrene Concentration and Body Mass Index: Findings from the 2020~2021 Korea National Health and Nutrition Examination Survey

Styrene, a volatile organic compound widely used in industry, may have health effects beyond its reported toxicity.This study analyzed 1,980 adults from the Eighth Korea National Health and Nutrition Examination Survey (2020~2021).After excluding missing indoor air styrene, body mass index (BMI), or covariate data, 763 adults were included.Indoor styrene concentrations were measured in the participants' households according to national air quality standards.Complex-sample general linear and multiple logistic regression models assessed the associations between styrene and BMI, adjusting for demographic, socioeconomic, lifestyle, and clinical factors.The weighted mean indoor styrene was highest in obesity class III (35.0 kg/m 2 ; 23.444.29 g/m 3 ) compared to normal weight (18.5~22.9kg/m 2 ; 3.160.43g/m 3 , P<0.001), with no significant differences among the other BMI categories.In fully adjusted models, the styrene concentration remained positively associated with the BMI (B=0.044,95% confidence interval [CI]=0.002~0.086,P=0.041).Logistic regression showed higher odds ratios (OR) for a BMI cut-off of 30 kg/m 2 (obesity class II) (OR=1.034,95% CI=1.015~1.053,P<0.001) and a BMI cut-off of 35 kg/m 2 (OR=1.143,95% CI=1.041~1.255,P<0.01).These findings suggest that indoor styrene exposure is independently associated with an increased BMI from class II (30), with the strongest effect in class III (35), and may be a modifiable environmental target for obesity prevention.