TPS 731: Neurological effects in children, Exhibition Hall, Ground floor, August 26, 2019, 3:00 PM - 4:30 PM Aim: To evaluate children’s anxiety according to PM2.5 exposure in a panel study. Methods: During the 3 waves (Mar, Jul, and Nov in 2018), 52 children were assessed indoor PM2.5 exposure at their home and 3 classrooms in two elementary schools, a city in Korea: for 7 days in each wave. Indoor exposure was calculated daily median, mean, and maximum using 30-minute mean of their own home and classroom in same time. Outdoor PM2.5 data was obtained from AirKorea, national ambient measurement of city spot near the school. Low (< 75 percentile) and high exposed group (≥ 75 percentile) were classified in daily statistic of indoor and outdoor PM2.5 level. Children’s anxiety was assessed via State Anxiety Inventory for children (SAIC) for 7 days in each wave. Gender and household income were assessed via questionnaire, and were used as covariates. Generalized estimated equation model was used to analyze for repeated measured data. Results: Using mean of PM2.5 concentration, SAIC were 4.5 point higher (p=0.02) in low-indoor and high-outdoor group, and 2.7 point lower (p=0.002) in high-indoor and low-outdoor group than in low-indoor and low-outdoor group. Using median and maximum of PM2.5 concentration, SAIC were 3.1 point (p<0.0001) and 1.8 point lower (p=0.04) in high-indoor and low-outdoor group than in low-indoor and low-outdoor group, respectively. Conclusions: We found controversial results Indoor and outdoor exposure to PM2.5 on children’s anxiety. The results imply that social environment arouse anxiety rather than current exposure level of PM2.5 per se. Acknowledgement: This research was supported by the National Strategic Project-Fine particle of the National Research Foundation of Korea(NRF) funded by the Ministry of Science and ICT(MSIT), the Ministry of Environment(ME), and the Ministry of Health and Welfare(MOHW).(NRF-2017M3D8A1092012)