Association of indoor and outdoor short-term PM2.5 exposure with blood pressure among school children.

The association between particulate matter and children's increased blood pressure is inconsistent, and few studies have evaluated indoor exposure, accounting for time-activity. The present study aimed to examine the association between personal short-term exposure to PM and blood pressure in children. We conducted a panel study with up to three physical examinations during different seasons of 2018 (spring, summer, and fall) among 52 children. The indoor PM concentration was continuously measured at home and classroom of each child using indoor air quality monitors. The outdoor PM concentration was measured from the nearest monitoring station. We constructed a mixed effect model to analyze the association of short-term indoor and outdoor PM exposure accounting for time-activity of each participant with blood pressure. The average PM concentration was 34.3 ± 9.2 μg/m and it was highest in the spring. The concentration measured at homes was generally higher than that measured at outdoor monitoring station. A 10-μg/m increment of the up to previous 3-day mean (lag0-3) PM concentration was associated with 2.7 mmHg (95%CI = 0.8, 4.0) and 2.1 mmHg (95%CI = 0.3, 4.0) increases in systolic and diastolic blood pressure, respectively. In a panel study comprehensively evaluating both indoor and outdoor exposures, which enabled more accurate exposure assessment, we observed a statistically significant association between blood pressure and PM exposure in children.