diy air purifier for fire season

hear me out: as a proud owner of a fancy, expensive air purifier (clean air is my singular passion), i love my DIY supplementary box fan purifier just as much if not more. snag a box fan and stick an air conditioning filter on the back (ideally with duct tape, but this one is just suctioned to the back by the flow), and crank it up to 3. no cheaper or easier way to protect your lungs and your peace during fire season or any bad AQI period. there’s a beefed up version you can make linked above, but even the single-filter version works wonders 💨