Vacuum upholstered chairs, sofas and carpets and wash bedding often. This cuts dust mite allergens that can cause health problems when they become airborne. Control moisture levels with a dehumidifier, air conditioner, or heat pump. Keep interior surfaces dry. Fix leaks promptly.
Mold grows on moist surfaces.
Open windows to increase air flow when possible. Dust furnishings with treated cloths. Change furnace air filters often. Use fine filters that trap microscopic dust. Use an upright, model with a brush roller or a tank model with a power brush attachment.