Supposedly HEPA filters get rid of mold spores. I've just recently started wiping my windows & window tracks periodically (I should do it daily). I live in a very damp climate, and when it's cold outside, the old windows get lots of condensation built up.
We have 2 HEPA filters in the house. I do notice that they work really well on smells, so it must be doing something. Another thing we have are DRIZAIR (?), little things you put crystals in that absorb moisture out of the air and it collects into a bowl....then you empty it. They sell them in sporting goods at walmart.