2024 Yes https://www.sciencedirect.com/science/article/pii/S0269749123022108?via%3Dihub Br?goszewska, Eva Europe Exposure Study Elementary (K-5) Bacteria Bacterial aerosol Bioaerosol Exposure dose Kindergarten Microbiological indoor air quality Size distribution The highest average concentration of bacterial aerosol was observed during autumn (1698 +/- 663 CFU/m3) in comparison to winter months (723 +/- 134 CFU/m3). Respirable doses for children and staff were 2945 and 2441 CFU/day during winter and 5988 and 4964 CFU/day during autumn, respectively. Deposition doses incorporated from empirical models for regional deposition in the respiratory tract showed that children in kindergarten absorb 33% less of bacteria into alveolar region if breath by nose instead of mouth. Additionally, risk assessment results indicate that the hazard indices for children attending kindergartens for 3 years and for staff working 25 years are below 1, suggesting minor risks associated with the inhalation of bioaerosols during autumn and winter. HI was <1, so the non-carcinogenic effects are on an acceptable level, but the indoor/outdoor ratio were 3.5 and 2.4 for autumn and winter, respectively, indicating children's and adult's exposure to bacterial aerosol should be reduced.