By Matthew Power. With the well-documented increase in allergy-sensitive individuals has come a predictable increase in stand-alone devices claiming to remove allergens from indoor air. But national health organizations, such as the American Lung Association (ALA), based in Minnesota, challenge the manufacturers' claims, saying that the small devices are more about hype than air "purification."

"It's virtually impossible to 'purify' indoor air," notes Bob Moffitt, communications manager with the ALA. "These devices are not going to make the air healthy if you're a smoker. The bottom line is, you get what you pay for, and a $150 unit is not going to do it."

"Claims about HEPA filtration are widely misused," he adds. "And research (see Web link) shows that most small units -- even those with true HEPA filters -- don't have enough air going through the filter to make a difference. And for God's sake, don't use any device that adds ozone to indoor air."

Moffitt adds that whole-house filtration systems and whole-house vacuums do a better job of removing particulates from indoor air. But even these systems won't remove dangerous gases such as carbon monoxide, as some people have come to believe.

"A better investment [than a portable air cleaner] would be to replace that 72-cent filter on your HVAC system with a good filter and turn on the furnace fan," Moffitt says. "But the truth is that a lot of the factors leading to poor indoor air quality can't be dealt with by air cleaners. They have to be cut off at the source."