Determination and risk assessment of airborne endotoxin concentrations in a university campus

Endotoxin is a cell-wall component of Gram-negative bacteria and is a hazardous biological substance that exerts adverse health effects. However, research on the determination and risk assessment of airborne endotoxins in university campuses is limited. In this study, the levels of airborne endotoxins were measured at different sites of a university campus in China. The arithmetic means for airborne endotoxin levels were 72 endotoxin units (EU)/m3 (range = 37.9-97.6 EU/m3). The airborne endotoxin levels varied at different sites and were typically high in laboratories (wastewater control and resource recovery laboratories) and school hospitals. Education environments had higher dose rates and risks (e.g., office) than recreational living places (e.g., gyms). The dose rates and health risks of airborne endotoxins followed the order children > adult male > adult female. Compared with skin contact, inhalation was the main way of airborne endotoxin exposure. No statistical differences were observed among the different sampling times on the same day. Both concentrations of total volatile organic compound and PM2.5 show positive correlations with airborne endotoxins, whereas culturable bioaerosol concentration, temperature, and relative humidity, were less significantly correlated with airborne endotoxin levels (p < 0.05).