OSKAR Evaporator Evaporative Humidifier An evaporative humidifier is a type of humidifier that uses a fan to blow air over a water-soaked filter, vaporizing the water and naturally dispersing it into the air. It works on the same principle as drying a wet towel with a fan. Because it doesn't use a heater, it's energy-efficient, safe, and prevents over-humidification. I purchased it one year ago. I haven't used it much. It's in good condition and works without any problems. As shown in the photos, the paper filter has discolored, but please replace it with a new filter after purchase.