Depends on what the air purifier was filtering. Mine does PM10, PM2.5, VOC and NO2. That means it’s filtering out particles down to 2.5mm plus volatile organic compounds (smoke, aerosolized oils, water vapour with pathogens, etc) and nitrous oxide.

The filter is a multi stage filter; the PM2.5 stuff passes right through the PM10 filter.

Interestingly, if I want to clear a room of smoke, sawdust, drywall dust or similar, what works the best is running my shop vac with a HEPA filter installed until I can’t smell the dust (usually around 5 minutes) and then I turn my air filter on full blast and it clears up the air in around 20 minutes. If I just ised the air filter, I’d probably clog it up and then just have to replace the comparatively expensive filter.