Our testing has shown some air cleaners to be of dubious value. Hiring an HVAC professional to check that your boiler or furnace is combusting and exhausting properly before every heating season is a must. There are also a number of easy--and often free--things you can do to improve the air quality inside your home:

1. Remove your shoes before entering the house to avoid tracking in dirt, dust, and pollen.
2. Limit dry cleaning, and air out treated items before bringing them indoors. And don't forget that there are alternatives to traditional dry cleaning.
3. Open windows frequently to allow polluted air to exit and fresh air to enter.
4. Install bathroom exhaust fans and a range hood--and use them.
5. Encase bedding in mite-proof covers and wash linens in the hottest water possible.
6. Dust with a damp rag or an electrostatically charged, or "magnetic," duster, which won't redistribute particles.
7. Vacuum often, including the refrigerator coils, which attract dust and often circulate it back into the air.
8. Don't burn candles, incense, tobacco products, or wood indoors.
9. Store cleaning products, chemicals, and firewood, the last of which can be a breeding ground for mold and insects, away from the living space in a shed or detached garage.
10. Before installing wall-to-wall carpeting, which is likely to emit VOCs (volatile organic compounds), air it out for a day or two. After installation, keep windows open in the room and run a fan for two or three days to provide ventilation.
11. Use paints labeled "low-VOC" and wear a respirator or mask when applying them.
12. Don't idle your car or operate outdoor power equipment or barbecue grills inside the garage or anywhere fumes can make their way indoors.