Ethan @ethanrosenthal.com · 28d I guess I should invest in an air purifier 6 likes 1 replies ? Reply Replies Justin Buist · 28d You can go budget. Handy for emergencies like this. Just strap a 20x20" MERV-13 furnace filter to the back of a 20" box fan. That filter was basically clean yesterday and you can already see the gunk it's picked up.