Associations of air pollution, road traffic noise, and greenness with adiposity markers in Swedish young adults

Background Environmental exposures have been associated with adiposity, but the evidence remains inconsistent. We examined associations of several environmental exposures with adiposity in young adulthood, and body mass index (BMI) trajectories from birth to 24 years. Methods In the Swedish birth cohort BAMSE, individual-level exposure to air pollutants, road traffic noise, and greenness was estimated using validated models. Time-weighted averages were calculated for early-life (first year) and recent exposure (five years prior to clinical assessment). At age 24, waist circumference and body composition (i.e., body/trunk fat percentage, fat mass index (FMI)) using bioimpedance were measured (n = 1612). BMI trajectories based on anthropometrics repeatedly measured up to 24 years were identified via latent class mixture modeling. Sex-specific associations were estimated via linear and multinomial logistic regression. Results One interquartile range increase in early-life fine particulate matter ≤2.5 μm (PM 2.5 ) exposure (1.18 μg/m 3 ) was associated with increased FMI in males (β = 0.30; 95% CI: 0.01-0.60), while in females, increase in recent PM 2.5 exposure was linked to several adiposity markers. Similar patterns were observed for other air pollutants. Early-life PM 2.5 exposure was also associated with an increased risk of being in the persistently high BMI trajectory group in females (OR = 2.39; 1.20-4.80). No consistent associations were observed with road traffic noise or greenness. Conclusion Air pollution exposure was associated with adiposity markers in young adults in a time- and sex-specific manner. In females, exposure to air pollution at birth was linked to a higher likelihood of persistently elevated BMI from birth to age 24 years.