This time claiming "air purifiers don't reduce exposure to viruses in classrooms"
BOLLOCKS
1st clue this was going to be a junk study: they did an RCT
Wrong tool
There is no equipoise, no unknown or barely discernible benefit to weigh against likely harm
2nd - Many studies already show cause & effect & mathematically quantify the relationship between exposure levels / reduction levels of pathogens in air and infections