The Israel Pediatric Association has issued a strong warning against the use of vaporizers (humidifiers) in children’s bedrooms, Kikar Hashabat reports.

Many parents use such machines during the winter in hopes of easing or preventing coughs and other respiratory illness.

Doctors warned that not only is there no proof that the machines are effective, but they can actually pose a health risk – and at times, can even prove fatal.

The threat that has pediatricians worried is Legionnaires’ disease, a potentially fatal illness caused by a bacteria carried by amoeba that grow in stagnant water. The still, room-temperature waters of a vaporizer can provide a welcome environment for the illness.

A young baby was recently hospitalized in critical condition in central Israel after contracting Legionnaires’ disease from the humidifier in his room. One year earlier, an 18-month-old baby boy died of the illness; in that case, too, the illness was caused by the vaporizer in his room.

The two cases and a third similar case led doctors to set up a committee to examine the issue. The committee came to the conclusion that pediatricians should recommend against use of vaporizers of both the hot-water and cold-water variety.

“The use of vaporizers has not been proven to be an effective treatment… Due to this fact, and in light of the significant – if rare – danger of contracting Legionnaires’, we do not recommend using vaporizers,” the pediatricians wrote.