Did you know that every cubic foot of air in the average home is loaded with about 3 million dust particles? Though most of these particles are so small that they're not visible, they can be a health hazard, particularly for people who suffer from allergies and bronchial problems.

Air cleaners (sometimes called air filters or air purifiers) can help reduce the problem by filtering out the microscopic particles caused by smoking, fireplaces, pets, molds, pollen, and other sources of indoor pollution. A variety of technologies are used by these devices to clean the air. And you can get types that filter the air in a single room or models that connect to the home's heating system to handle the entire house.

In this section of HomeTips, you'll learn how air purifiers work, how to make informed buying decisions, do-it-yourself maintenance and care, and more.