Zappers are great for mold issues along with mites. My zapper kept me alive for a long time until I was finally able to get a frequency generator.
Did you know you can just use a 9 volt battery and get the same effect as a zapper?
1) Hold the battery in one hand.
2) Wet this hand's thumb and place it on one of the terminals (the little metal cylinder things).
3) With your other hand (also wet), tap repeatedly on the other terminal. Tap as fast as possible.
For best results cover your hands with a wet paper towel, instead of just using your bare skin as contact.