A humidifying apparatus includes a base, a water tank removably mounted on the base for supplying water to a chamber of the base, and a motor-driven impeller for generating an air flow over water stored in the chamber. An ultraviolet radiation emitting lamp irradiates water stored in the chamber. The air flow is humidified with water from the chamber, and conveyed by an outlet duct towards an air outlet for emission from the apparatus. A detachable section of the water tank is opaque to ultraviolet radiation and is positioned over the chamber when the water tank is mounted on the base. The detachable section of the water tank includes an air inlet of the outlet duct and a flange for occluding a peripheral portion of the chamber.