What are the best air filters for mold and mycotoxins that are small enough to fit in a small room, like a bathroom? Does a large standalone air purifier need to clean at .003 microns to clear mold from the air?

While having an air purifier with a HEPA filter capable of capturing particles as small as 0.003 microns can be effective, it’s important to note that mold spores typically range in size from about 1 to 30 microns. Most standard HEPA filters can capture particles as small as 0.3 microns, which is sufficient for trapping mold spores.

Here is a high flow HVAC filter replacement option: https://www.filtrete.com/3M/en_US/p/d/b00039984/