Air cleaners.(Home & Yard: More Value for Less)(Buyers guide)

Even the best air cleaner may be a questionable investment, since there's little medical evidence that air cleaners alone reduce the effects of indoor pollutants for those with asthma and allergies.

The air inside your home is more polluted than the air outside, according to estimates by the U.S. Environmental Protection Agency. But that doesn't mean it's unhealthy and needs to be cleaned--or that you need an air cleaner.

Before you buy one, try some commonsense solutions to eliminating and controlling pollutants and ensuring proper ventilation. If these aren't enough, an air cleaner may help. But only people with respiratory problems are likely to benefit.

For homes with forced-air heating and cooling, a competent, professionally installed whole-house air cleaner is likely to outperform most slide-in filters. (Two filters we tested, the American Air Filter Dirt Demon Ultra High Efficiency and the 3M Filtrete Ultra Allergen Reduction 1250, performed well.) Otherwise, your only option is a room air cleaner.

WHAT'S AVAILABLE

Whole-house air cleaners. Major brands include 3M, American Air Filter, Aprilaire, Carrier, Honeywell, Lennox, Precisionaire, Purolator, and Trane. Models range from low-cost fiberglass furnace filters to electronic precipitators, which must be installed professionally in the duct system.

Furnace filters range from plain matted-fiberglass (about $1), meant to trap large particles of dust and lint, to electro-statically charged pleated filters ($10 to $30), which are designed to attract pollen, lint, pet dander, and dust.