This is a link for last month's Interagency Committee on Indoor Air Quality (CIAQ) webinar. Dr. Dustin Poppendieck, an engineer at the National Institute of Standards and Technology (NIST), presented on the efficacy and ozone risks of 222 nm UV lamps.
Main point: there is balance between biological risks from infectious aerosols, and chemical risk from ozone production. The risk balance will change based on community transmission rate, occupancy rate, and kind of occupancy.
"[UVC] is a complex chemistry, it has complex risks, it's not going to be a uniform magic bullet that we can apply everywhere, but it definitely probably will be useful in some locations."