As far as air purifiers are concerned, there are well-regarded designs you can buy that use PC fans (you can order without fans and put in your choice of fans)

As far as air purifiers are concerned, there are well-regarded designs you can buy that use PC fans (you can order without fans and put in your choice of fans) and furnace filters. I just got a North Box Polaris: https://aidankepo.wixsite.com/northboxsystems https://aidankepo.wixsite.com/northboxsystems. Luggable supplies an equivalent for Americans.