Is it possible for an aircraft humidifier to spread Legionella? The humidifier is comprised of a glass fiber distribution pad with specially designed water channels that are moistened via spreader system to cool and humidify the air passing over it, utilizing the technology of evaporative humidification. When dry air passes over the moist surface, the water evaporates and the air is humidified while being cooled. There is no sump involved in the system and any excess water leaves via a drain port.
Evaporative cooling generally presents less risk for Legionella transmission. If the water supplying the system is potable cold water and not stored in any tank prior to use, it is unlikely that Legionella would grow in that water.