Disclosed herein are wearable devices for dispensing insect repellents, fragrances, and/or other chemicals along the outside of the clothing of a human, to avoid the need to apply such chemicals directly to clothing or to human's skin. The devices have an on/off switch that automatically controls a shutter which enables and restricts air flow, while also controlling fan operation and covering of a use-up cue. The device also is designed to prevent fan operation when an impregnated slab is not present. Also disclosed are preferred refills for use with such devices.