Protip: you can turn a box fan into an incredibly effective air purifier[0] (particle measurements in thread). The one they show is pretty elaborate, using 4 filters and some construction, but you can also use a single filter and slap it on the back of the box fan and have similar results. The air purifier industry is more about aesthetics than it is function.
0. https://twitter.com/LazarusLong13/status/1425517352624410627