using air purifiers like that for corona is mostly theater anyway, since air purifiers don't filter the air evenly (despite the misnomer metric "air changes per

using air purifiers like that for corona is mostly theater anyway, since air purifiers don't filter the air evenly (despite the misnomer metric "air changes per hour") in a room. mostly, it filters really well near the purifiers and poorly everywhere else. this of course depends on the strength of the fan, but for most consumer air purifiers, it's likely a few feet radius at best. that's not to say that even that isn't worth having in an average bedroom, but in a classroom, it's likely not doing much at all. also, you're already distancing (which is doing nearly all the work there) and wearing masks (which is mostly theater in a distanced classroom as well). the virus isn't free-floating live in the classroom. most virus falls to the ground directly. of what's aloft, it becomes inactivated pretty quickly for all sorts of reasons (dessication, ph, temperature, radiation, etc.) and most likely won't land anywhere near a viable infection spot. so almost no active virus is filtered out before it has a chance to reach a moist, viable passageway in another person. even huge central commercial systems likely wouldn't filter out coronavirus before they die off or land somewhere harmlessly. it's another potential intervention that sounds plausible on the surface, but is mostly useless against covid.