The present invention relates to a dispensing device for at least one air treatment agent comprising at least one airborne agent detector operable to detect airborne agents in the air； receiving means for receiving at least one source of air treatment agent； and control means for releasing an amount of at least one air treatment agent from a source thereof received in the receiving means when a current airborne agent level detected by the airborne agent detector deviates from a background airborne agent level detected by the airborne agent detector by more than a predetermined amount, wherein the background airborne agent level is calculated by the device. The present invention also relates to a method of dispensing at least one air treatment agent.
