1. Keep humidity under 50% by using air conditioning - possibly supplemented with dehumidifiers - in the summer. Use a gauge to measure indoor humidity. Small air dryers may be used to prevent mold growth in closets.

2. Avoid over-humidification. Either do not use a humidifier in the winter, or if you do, limit its output so that humidity remains under 50%. Use only humidifiers that have a heating element that prevents mold from growing in the unit itself.

3. Allow moisture to escape from the home. Ventilate the shower and cooking areas. Vent your clothes dryer to the outdoors. Open windows when outside humidity is low.

4. Do not store firewood indoors, and avoid live Christmas trees. Do not repot plants indoors. Mold lives on the bark of trees and in soil.

5. Avoid greenhouses, antique shops, summer cottages, and musty hotel rooms.

6. Wear a facemask, and possibly goggles, if you must cut grass, rake leaves, work in a barn, or be exposed to compost.