Seasonal concentrations and size distributions of culturable bacterial aerosols inside and outside university classrooms – A case study in Beijing

Disruption and recovery of outdoor bioaerosols before, during, and after the COVID-19 outbreak at a campus in Central China: pathogen composition, particle size distribution, influencing factors, and exposure risk

“…There have also been previous studies of bioaerosols in outdoor environments on campuses; for example, the mean bacterial concentration of 237 CFU m −3 measured by Fang in the outdoor environment of a university in Hangzhou 15 and the outdoor concentration of 131 CFU m −3 measured by Heo in a university in Korea 31 are comparable to the results of this study. In Tehran, Iran, there are campus outdoor ambient bacterial concentrations (300 CFU m −3 ) outside of school dormitories, 16 and a campus in Turkey during the COVID-19 lockdown period (215–514 CFU m −3 ), 32 the average outdoor concentration in a campus in Beijing (314 ± 229 CFU m −3 ), 12 an academic institution in the Central Plains (251–610 CFU m −3 ), 14 and a campus in Taiwan (714–1706 CFU m −3 ). 13…”

“…And the smaller the particle size, the easier it is for bacteria to adsorb on fine particles and remain suspended in the air for a long time, where they can be inhaled and deposited in the human respiratory system, making them more likely to affect humans; 37 whereas some studies have demonstrated that particles smaller than 2.5 μm are more hazardous to human health, 5 previous studies have shown that the particle size of bacteria outside university classrooms was primarily distributed between 2.1 and 4.7 μm. 12…”

“…Previous research on microbial concentrations and species in outdoor campus environmental bioaerosols revealed that Zhao detected average bioaerosol concentrations of 314 ± 229 CFU m −3 in 11 university classrooms before COVID-19. 12 Hsu measured bioaerosol concentrations of 714 ± 1706 CFU m −3 at a Taiwanese campus. 13 In contrast Gupta conducted a 6 months study at an Indian Institute of Technology (IIT) and showed that the bioaerosol concentrations in the outdoor environment of this campus ranged from 251 to 610 CFU m −3 and the main genera were Bacillus , Staphylococcus , Micrococcus , Streptococcus , and Enterococcus .…”