Humidifier type, care can prevent bacteria spread

The instructions on most humidifiers say to clean and dry them daily or risk bacteria growth, but that doesn't always happen.

An informal poll found one in four people admitted to cleaning their humidifier only once a month or even less.

The concern is whether or not that puts human health at risk.

Humidifiers are supposed to add moisture to the air, but if it's not cleaned often enough, it could also be spreading bacteria, which could be a problem for people with asthma or allergies – it can even cause flu-like symptoms.

Consumer Reports looked at 35 humidifiers: 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.

Some manufacturers make claims of “bacteria-free vapors,” “germ-free mist,” and “antimicrobial material,” but those claims might not be reality.

“Humidifiers with antimicrobial claims weren’t necessarily any better at preventing bacterial growth or emitted bacteria," said Dory Sullivan of Consumer Reports.

The difference lies in the type of humidifier.

All of the ultrasonic and all but one of the vaporizers emitted some bacteria, but none of the 10 evaporative models with a wick filter did.

No matter which type of humidifier it is, though, the best bet is to empty, rinse and dry it out every day, and once a week follow the manufacturer’s instructions on how to disinfect the tank.