2021 No https://pubmed.ncbi.nlm.nih.gov/34278392/ Fu, Xi Asia Experimental Observational Epidemiology Study Students Middle/Jr High (6-8) Bacteria Allergens Respiratory symptoms Fifteen bacterial genera in the classes Actinobacteria, Alphaproteobacteria, and
Cyanobacteria were protectively associated with respiratory infections (p< 0.01), and these bacteria were mainly derived from the outdoor environment. Previous studies also reported that outdoor environmental bacteria were protectively associated with chronic respiratory diseases, such as asthma, but the genera identified were different between acute and chronic respiratory diseases. Four fungal genera from Ascomycota, including Devriesia,
Endocarpon, Sarcinomyces and an unclassified genus from Herpotrichillaceae, were protectively associated with respiratory infections (p < 0.01). House dust mite (HDM) allergens and outdoor NO2 concentration were associated with respiratory infections and infection-related microorganisms. A causal mediation analysis revealed that the health effects of HDM and NO2 were partially or fully mediated by the indoor microorganisms.