2017 No https://onlinelibrary.wiley.com/doi/10.1111/pai.12704 Rufo, João Cavaleiro Europe Exposure Study Modeling Students Elementary (K-5) Bacteria Fungi Respiratory symptoms Endotoxins Exposure Fungi Indoor air Microbiologic diversity microbiome School Sensitization Classrooms with increased diversity scores showed a significantly lower prevalence of children with atopic sensitization, but not asthma. The risk of sensitization increased with increasing endotoxin exposure in classrooms. Similarly, significantly higher concentrations of Penicillium spp were found in classrooms with a higher number of children with atopic sensitization.