Assessment of dust endotoxins, airborne bacteria, and PM2.5 at old-age nursing homes and children's daycare centers in the Seoul metropolitan area, South Korea

Indoor air pollutants are associated with adverse health effects in people, particularly children and older adults—the most vulnerable groups health-wise who also happen to spend much of their time in indoor environments. To contribute to knowledge on how these groups can be protected, this study sought to determine the relationships between indoor pollutants (dust endotoxins, airborne bacteria (AB), and particulate matter (PM_2.5)) and environmental factors (temperature, relative humidity (RH), use of air conditioners (AC), use of windows, and season). For each pollutant, 360 samples were collected from 31 old-age nursing homes and 31 daycare centers in South Korea. The Mann–Whitney U test, Kruskal–Wallis rank sum, Spearman's rank analysis, and multivariate regression were used to determine whether there were significant differences between indoor pollutants and environmental factors. Dust endotoxin values ranged between < LOD and 632 EU/mL and between 306 and 632 CFU/m³ for AB, and ranged from 3.9 to 32.5 µg/m³ for PM_2.5. Dust endotoxin levels showed a significant relationship with RH and season in the multiple regression analysis. Periodic AC filter cleaning and exchange, as well as proper RH management in these facilities may help reduce indoor biological pollutants. The findings of this study are informative for addressing the respiratory health issues of older people and children in indoor facilities.