Concentrations of PM10 and airborne bacteria in daycare centers in Seoul relative to indoor environmental factors and daycare center characteristics

The purpose of this study was to measure concentrations of PM10 and airborne bacteria (AB) to determine how each one of them correlated with particular indoor environmental factors and characteristics of daycare centers in Seoul, South Korea.PM10 and AB were sampled in 330 daycare centers in the middle of a classroom, along with measurements of temperature and relative humidity. Spearman’s correlation and Mann-Whitney analyses were used to examine the relationship among and differences between PM10 concentration, AB concentration, indoor environmental factors, and daycare center characteristics.There were significant correlations between PM10 concentration and AB concentration (r = 0.128, p < 0.05), temperature (r = 0.153, p < 0.01), and relative humidity (r = 0.185, p < 0.01). PM10 concentrations with two or more windows; a heating, ventilation, and air conditioning (HVAC) system; and the use of air purifier were lower than concentrations with one window, window ventilation only, and no air purifier. AB concentrations were significantly higher when daycare centers had only one window and used only window ventilation (p < 0.05).Though there are many uncontrollable outdoor environmental factors that influence air quality, we demonstrated that using an HVAC system and an air purifier significantly reduces PM10 concentrations and is a practical change that could be implemented to improve the indoor air quality of daycare centers.