1. Keep you house clean. A clean house may be healthier house, because good indoor hygiene can greatly cut down on dust and animal dander. 2. Keep the greenery outdoors. In-door plants are pretty, but they can also collect and foster the growth of mold. 3. Change your filters. 4. Invest in air an purifier 5. Let the fresh air in. Even in cold months, open from time to time to allow fresh air to move in the house.