Supplementary Material for: Ambient air pollution is particularly associated with visceral fat accumulation in men: A large-scale Korean adult study

Introduction: Long-term air pollution exposure is associated with obesity, but its impact on visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) distribution remains unclear. This study investigated the association between air pollution and abdominal fat indicators, including total adipose tissue (TAT), VAT, SAT, and the visceral-to-subcutaneous fat ratio (VSR), stratified by sex and obesity status based on body mass index (BMI). Methods: A total of 8912 Korean adults who underwent health check-ups at Seoul National University Hospital were included. Abdominal fat was measured using CT scans. Annual average air pollution exposure levels, including particulate matter ≤2.5μm in diameter, particulate matter ≤10μm in diameter (PM₁₀), NO₂, SO₂, CO, and O₃, were estimated using the Community Multiscale Air Quality model. Ambient air pollution exposure and abdominal adiposity-related traits were analyzed using multiple linear and logistic regression, stratified by sex. Results: Annual exposure to PM₁₀ and SO₂ was positively associated with VAT (PM₁₀: β = 2.29, 95% CI: 0.53–4.04, p = 0.01; SO₂: β = 4.19, 95% CI: 2.43–5.94, p <0.001) and VSR (PM₁₀: β = 0.03, 95% CI: 0.01–0.05, p = 0.02; SO₂: β = 0.05, 95% CI: 0.03–0.07, p <0.001) in men. These associations were stronger in men with high BMI, but no significant associations were found in women. Negative associations with SAT were observed for PM₁₀ (β = -1.94, 95% CI: -3.44 to -0.45, p = 0.01) and SO₂ (β = -2.47, 95% CI: -3.97 to -0.98, p = 0.001) in men and for PM₁₀ (β = -4.58, 95% CI: -7.23 to -1.93, p = 0.001) and SO₂ (β = -8.13, 95% CI: -10.78 to -5.48, p <0.001) in women. Conclusion: Long-term exposure to air pollutants, including PM₁₀ and SO₂, may have detrimental effects by increasing visceral fat accumulation and reducing beneficial subcutaneous fat, especially in men with obesity.