Distribution and Influencing Factors of Airborne Bacteria in Public Facilities Used by Pollution-Sensitive Population: A Meta-Analysis

The aim of this study was to support management of airborne bacteria in facilities used by pollution-sensitive individuals (in daycares, medical facilities, elder care facilities, and postnatal care centers). A field survey was conducted on 11 facilities from October 2017 to April 2018. Elder care facilities in industrial, urban, and forested areas were excluded. Two indoor, and one outdoor, measuring points were selected per facility. These points were located in areas most often used by the residents. Measurements were taken at random time-points before February 2018 and at specific times in the morning and afternoon thereafter. The relationships among bacterial counts, carbon dioxide concentrations, dust levels, temperature, relative humidity, and ventilation were examined. The pooled average bacterial counts at the daycares, medical facilities, elder care facilities, and postnatal care centers were 540.25 CFU m(−3), 245.49 CFU m(−3), 149.63 CFU m(−3), and 169.65 CFU m(−3), respectively. Considering the upper 95% confidence interval, the bacterial counts in many daycares may in fact be >800 CFU m(−3), which is the threshold set by the Korean Ministry of the Environment. The pooled average indoor: outdoor bacterial count ratio was 1.13. Indoor airborne bacterial counts were influenced mainly by their sources. This study found no significant correlations among indoor temperature, relative humidity, carbon dioxide concentration, dust levels, and airborne bacterial counts, unlike previous studies. Airborne bacteria management at daycares should be a top priority. The sources of airborne bacteria must also be identified, and a management plan must be developed to control them.