Objective: : We collected 6,327 participants who had a health check-up between September 2016 and December 2020 in Seoul National University Hospital. We evaluated the association between the body composition (skeletal muscle mass [SMM] (kg), percent body fat [PBF] (%), and body fat mass [BFM] (kg)) and air pollutants (PM2.5, PM10, NO2, SO2, and CO) in linear regression adjusted by sex, age, education (low, middle, and high), occupation (10 levels), hemoglobin, albumin, comorbidity (cancer, diabetes, and hypertension), drinking and smoking status (3 levels), and MET score of vigorous-intensity activity. Individual interpolations of air pollutants exposure were estimated by inverse distance weighting (IDW). Methods: The study population had 54.1 ± 12.94 age, and 51% were male. More than half of the participants were the most educated (69%) and non-smoker (59%). An IQR increase of SO2 for 0.0006 ppm and NO2 for 0.007 ppm was significantly associated with 0.12 kg (95% CI 0.04-0.20) and 0.12 kg (95% CI 0.02-0.22) reduced SMM, respectively. In addition, we observed the exposure effects of CO on 0.17 % (95% CI 0.01-0.35) PBF increase. Results: Our findings showed long-term exposure to air pollutants was associated with sarcopenia and obesity to healthy adults, and it can be used as an indicator for maintaining a healthy life and support scientific evidence for health policy. Conclusions: Objective: Decreased muscle and increased fat mass is associated with greater frailty and weakness, and finally lead to lower quality of life. Although assessing body composition have been major components of physical function in aging society, little studies have examined the association between exposure to air pollutants and body composition in general population. Methods: : We collected 6,327 participants who had a health check-up between September 2016 and December 2020 in Seoul National University Hospital. We evaluated the association between the body composition (skeletal muscle mass [SMM] (kg), percent body fat [PBF] (%), and body fat mass [BFM] (kg)) and air pollutants (PM2.5, PM10, NO2, SO2, and CO) in linear regression adjusted by sex, age, education (low, middle, and high), occupation (10 levels), hemoglobin, albumin, comorbidity (cancer, diabetes, and hypertension), drinking and smoking status (3 levels), and MET score of vigorous-intensity activity. Individual interpolations of air pollutants exposure were estimated by inverse distance weighting (IDW). Results: The study population had 54.1 ± 12.94 age, and 51% were male. More than half of the participants were the most educated (69%) and non-smoker (59%). An IQR increase of SO2 for 0.0006 ppm and NO2 for 0.007 ppm was significantly associated with 0.12 kg (95% CI 0.04-0.20) and 0.12 kg (95% CI 0.02-0.22) reduced SMM, respectively. In addition, we observed the exposure effects of CO on 0.17 % (95% CI 0.01-0.35) PBF increase. Conclusions: Our findings showed long-term exposure to air pollutants was associated with sarcopenia and obesity to healthy adults, and it can be used as an indicator for maintaining a healthy life and support scientific evidence for health policy.