A wearable device for dispensing an air treatment chemical, the device comprising: a housing (20, 50, 80) including an inlet for permitting air to enter into an interior space of the housing (20, 50, 80) and including an outlet for permitting air mixed with air treatment chemical to exit the interior space; a substrate positioned in the housing (20, 50, 80), the substrate bearing an air treatment chemical; a power supply (75, 76, 77, 78) mounted in the housing (20, 50, 80); a motor mounted in the housing (20, 50, 80), the motor being powered by the power supply (75, 76, 77, 78); and a fan mounted in the housing (20, 50, 80), the fan being arranged to move air from the inlet adjacent the substrate so as to mix air treatment chemical into the moving air, and then to deliver the mixture of air and air treatment chemical through the outlet to outside of the housing (20, 50, 80); characterized in that: the fan includes a rotor connected to the motor and the fan includes 12 to 18 spaced apart blades (68a-68n) connected to and extending away from the rotor; the plurality of such blades (68a-68n) each having a body extending from an inner edge to an outer edge, the body having a length measuring 80% to 130% of a distance from a centerpoint of the rotor to the inner edge of the blade; and the outlet of the housing comprises a plurality of spaced apart openings, the openings being spaced around at least 180 degrees of the sidewall structure of the housing (20, 50, 80); a flow path from the fan to the openings being unobstructed. a housing (20, 50, 80) including an inlet for permitting air to enter into an interior space of the housing (20, 50, 80) and including an outlet for permitting air mixed with air treatment chemical to exit the interior space; a substrate positioned in the housing (20, 50, 80), the substrate bearing an air treatment chemical; a power supply (75, 76, 77, 78) mounted in the housing (20, 50, 80); a motor mounted in the housing (20, 50, 80), the motor being powered by the power supply (75, 76, 77, 78); and a fan mounted in the housing (20, 50, 80), the fan being arranged to move air from the inlet adjacent the substrate so as to mix air treatment chemical into the moving air, and then to deliver the mixture of air and air treatment chemical through the outlet to outside of the housing (20, 50, 80); characterized in that: the fan includes a rotor connected to the motor and the fan includes 12 to 18 spaced apart blades (68a-68n) connected to and extending away from the rotor; the plurality of such blades (68a-68n) each having a body extending from an inner edge to an outer edge, the body having a length measuring 80% to 130% of a distance from a centerpoint of the rotor to the inner edge of the blade; and the outlet of the housing comprises a plurality of spaced apart openings, the openings being spaced around at least 180 degrees of the sidewall structure of the housing (20, 50, 80); a flow path from the fan to the openings being unobstructed. the fan includes a rotor connected to the motor and the fan includes 12 to 18 spaced apart blades (68a-68n) connected to and extending away from the rotor; the plurality of such blades (68a-68n) each having a body extending from an inner edge to an outer edge, the body having a length measuring 80% to 130% of a distance from a centerpoint of the rotor to the inner edge of the blade; and the outlet of the housing comprises a plurality of spaced apart openings, the openings being spaced around at least 180 degrees of the sidewall structure of the housing (20, 50, 80); a flow path from the fan to the openings being unobstructed.