Association of airborne endotoxin concentrations with pulmonary function and airway inflammation among students

Abstract

TPS 752: Respiratory effects and allergies, Exhibition Hall, Ground floor, August 27, 2019, 3:00 PM - 4:30 PM Background: Few studies have evaluated the short-term effects of airborne endotoxin on respiratory health. We evaluated the relationship between exposure to airborne endotoxin and pulmonary function and airway inflammation among healthy students. Methods: A panel study was conducted in 41 healthy students aged 16 years, for about 1 month in May 2015, in a school on an isolated island in the Seto Inland Sea, Japan. Daily measurements of peak expiratory flow (PEF) and forced expiratory volume in 1 s (FEV1) were performed. Fractional exhaled nitric oxide (FeNO) was also measured once a week during the study period. Coarse (PM10-2.5) and fine (PM2.5) particulate matter samples were collected every 24 h from inside and outside the classroom, and endotoxin concentrations in both fractions were measured using the kinetic Limulus Amebocyte Lysate assay. The associations of pulmonary function and FeNO with 24-h endotoxin concentrations before each measurement were analyzed using mixed-effects models. Results: A decrease in FEV1 was significantly associated with endotoxin concentrations in outdoor PM2.5 (-0.03 L [95% confidence interval (CI): -0.05, -0.01] for an interquartile range (IQR) increase of 0.07 EU/m3). Neither PEF nor FeNO was associated with endotoxin concentrations in any fractions. Among subjects with wheezing during or after exercise, the increase in FeNO was significantly associated with endotoxin concentrations in indoor and outdoor PM10-2.5 (4.4 ppb [95% CI: 0.2, 8.5] and 7.4 ppb [95% CI: 0.3, 14.4] for each IQR increase of 0.12 and 0.19 EU/m3, respectively). Indoor and outdoor mass concentrations of each fraction were associated with neither pulmonary function nor FeNO. Conclusions: These results suggest that endotoxin in outdoor PM2.5 may affect pulmonary function among healthy students. Additionally, endotoxin concentration in PM10-2.5 was significantly associated with FeNO in students with wheezing during or after exercise, indicating the potential of endotoxin to cause airway inflammation.