If you smoke, quit. Most hardware stores carry inexpensive ones. Avoid secondhand smoke. This applies to anyone with breathing difficulties. Install an electronic air filtering system or use an air purifier in your home, especially in the bedroom.
Tests show that air filters help clear the air of allergy-causing agents.
Molds and mildew grow on leaves after they've been on the ground for a few days. Keep your basement dry, well ventilated, and well lit. Use dehumidifiers and exhaust fans to reduce moisture in the air. Get rid of house plants. Avoid barns, chicken coops, damp basements, and attics.