Characteristics and Exposure Risk of Indoor Bioaerosols Before and after Covid-19 on Campus in Central China

This study focused on indoor bioaerosols in the student dormitory (SD), dining rooms (DR), and study rooms (SR) of a university in central China from 2019 to 2021. To explore the changes in campus indoor bioaerosols in different prevention and control stages before and after the outbreak of COVID-19. An Eight-Stage Andersen impactor was used to capture bioaerosols, and high-throughput sequencing was performed to analyze their species composition. The exposure risks of students were assessed through non-carcinogenic risk. The results showed that the indoor bioaerosols concentrations in SD, DR and SR were 110±10 CFU/m3, 146±14 CFU/m3 and 113±17 CFU/m3 respectively in 2020, significantly higher than the indoor bioaerosols concentrations in 2019 and 2021. The proportions of bacteria adhering to particles smaller than 3.3μm in the air of SD in 2021 and DR in 2020 were lower than that in 2019. In 2020-2021, the relative abundance of Brevundimonas, Acinetobacter, Pantoea and Bacillus increased compared with that in 2019, and the relative abundance of Sphingomonas decreased. The potential pathogenicity of bioaerosols in DR in 2021 was the highest. The prevention policy of COVID-19 has restricted students' study and life, which may affect the characteristics of indoor bioaerosols on campus. During the closed management of COVID-19 epidemic, limiting the flow of people in the enclosed space and increasing ventilation are important measures to reduce the risk of indoor bioaerosols.