The Therapure ultrasonic humidifier from Envion produces healthy, moisturized air and helps to reduce flu viruses in your home. Choose the cool mist setting to help you breathe more comfortably and relieve your dry nose and skin. Choose the warm mist setting to relieve cold and flu symptoms, including congestion, cough and sore throat. The tank fill light lets you know when the water level is low, and the humidifier shuts off automatically when the tank is empty or the desired humidity level is reached.