The pandemic conditions seriously affect everyday life in schools. Wearing mask, distancing, and permanently open windows are useful measures, but not always an option during the colder season. Therefore, electric air cleaners are discussed to enable safe classes by providing air that is free of infectious aerosols. The clean air delivery rate (CADR) is often used as a measure to select an appropriate air cleaner for a specific room size and situation. In our study we determined the viable virus removal by a commercial air cleaner in a 30 m3 environmental test chamber. The same air cleaner was then operated in a test room with typical classroom furnishing. Here, the concentration of viable viruses was measured under different scenarios (air cleaner positions, window open/closed). The results show that the very effective removal of viruses seen in the test chamber cannot always be observed in the test room.
Uhde et al. (Sat,) studied this question.