Bacteria-breeding humidifiers

FRESNO, Calif. (KFSN) -- With winter's drier air, people start using humidifiers. Manufacturers recommend cleaning them every day, but according to an informal Consumer Reports' poll, one in four people clean their humidifier only once per month or even less. Consumer Reports' latest research finds bacteria can grow fast -- putting your health at risk.

A dirty humidifier can emit bacteria into the air, and that could be a problem for people with asthma or allergies and cause flu-like symptoms. Many manufacturers make anti-bacterial claims like "produces pure bacteria-free vapors, "germ-free mist," and "antimicrobial material."

Consumer Reports took a closer look at 34 humidifiers in three categories-- vaporizers, which emit steam, ultrasonic humidifiers that release a fine mist into the air, and evaporative humidifiers, which blow air over a wet wick filter. Over the course of three days, testers measured the microbial growth in the humidifier's tanks.

In a second test, they added bacteria to each tank and measured whether any came out in the humidifier's mist. Humidifiers sold with antimicrobial claims weren't necessarily any better at preventing bacterial growth.

What did make a difference in Consumer Reports' tests was the type of humidifier. All of the ultrasonic humidifiers and all but one of the vaporizers emitted some bacteria. But none of the 10 evaporative wick models did.

If you have an infant or if you suffer from asthma or allergies, consider the Vicks Warm Mist Vaporizer V150SGN for $15, or for larger rooms, the Honeywell HCM-350 evaporative humidifier for $60. Neither grew or emitted any bacteria in Consumer Reports' tests.

With any type of humidifier, the safest approach is to empty, rinse, and dry it out every day. And once per week, follow the manufacture's instructions on how to disinfect the tank.