Co-generated particles, but not ambient particles, shield bioaerosols from Far-UVC inactivation and increase exposure to viable bioaerosols.

Far-UVC radiation can be an efficient and secure approach for bioaerosol sterilization in occupied high-risk settings like healthcare facilities. In dental clinics, aerosols produced by dental procedures are characterized by the existence of co-generated particles such as grind tooth fragments, restorative materials, and dental calculus. In this study, the influence of particles on far-UVC disinfection efficiency was investigated. First, the susceptibility of aerosolized bacteria and viruses to far-UVC radiation was experimentally measured under three conditions, i.e., without particles, with co-generated particles, and with ambient particles. The findings indicated that co-generated particles, but not ambient particles, shielded bioaerosols from far-UVC inactivation. The far-UVC susceptibility of aerosolized E. coli and MS2 with co-generated particles was only 49 % and 40 % of that without particles, respectively. Then, the impact of co-generated particles on far-UVC disinfection performance and occupational exposure to viable bioaerosols in a dental clinic was investigated by numerical method. It was found that, due to the shielding effect of co-generated particles on bioaerosols against far-UVC inactivation, the dentist's exposure to viable bioaerosols increased by 41 %. Thus, it is crucial to consider the shielding effect of co-generated particles during the far-UVC system design to ensure reliable bioaerosol inactivation.