Is the air purifier good for dust, pet dander or mold spores?

Yes. The air purifier is equipped with a HEPA filter which is excellent at trapping minuscule particles as small as 0.3 microns. To put that in perspective, the diameter of a strand of hair is 30 microns while a pollen particle is as small as 10 microns. The HEPA filter is excellent at trapping all physical matter, such as dust, pollen, pet dander, mold spores and more.