As soon as the evidence around airborne transmission was coming out, I ordered an air purifier and used to successfully quarantine a few covid-infected family members without further transmission.
It is absolutely criminal that we didn't get a new Clean Air Act for indoor air as a result of the pandemic. Pathogens, allergens, pollutants, and even just plain buildup of carbon dioxide in crowded areas--these can all be mitigated with proper ventilation and filtration.