Found this site which has a lot of info on cleaning the air, specifically for covid. So a lot of resources on UV-light, ventilation, and air filtration.
Also, if you want to check co2 levels in places you live or work, to test air quality, the Vitalight mini-co2 detector is very useful and inexpensive compared to what is normally recommended. I just got one to test air quality at work. It's basically 30-40 dollars compared to other models which are sometimes hundreds of dollars each.