A dispensing device for dispensing an air treatment chemical, the device comprising: a housing (11, 12, 13, 14) with an inlet and an outlet and an electrically powered fan (19, 20, 21, 24) to pull air in through the inlet and exhaust the air through the outlet, creating an air stream through the housing; a switch for turning the fan on and off; a movable shutter that blocks the air flow when in a first, closed position and allows the air to flow when in a second, open position, the shutter having a projection thereon that interacts with the switch so that moving the shutter to the second, open position activates the switch to turn on the fan: characterized by a rotatable finger that must be rotated by interaction with the projection of the shutter before the switch can be activated, the dispensing device further including a table to receive and hold a substrate exposed to the air stream, wherein the substrate bears an air treatment chemical to be dispensed, with the substrate held in interactive relation with the finger so as to partially rotate the finger from a designated position when no substrate is held by the table, to a selected position when a substrate is held by the table, and wherein when the finger is in the selected position it can be further rotated there from by movement of the projection as the shutter is moved to activate the fan. a housing (11, 12, 13, 14) with an inlet and an outlet and an electrically powered fan (19, 20, 21, 24) to pull air in through the inlet and exhaust the air through the outlet, creating an air stream through the housing; a switch for turning the fan on and off; a movable shutter that blocks the air flow when in a first, closed position and allows the air to flow when in a second, open position, the shutter having a projection thereon that interacts with the switch so that moving the shutter to the second, open position activates the switch to turn on the fan: characterized by a rotatable finger that must be rotated by interaction with the projection of the shutter before the switch can be activated, the dispensing device further including a table to receive and hold a substrate exposed to the air stream, wherein the substrate bears an air treatment chemical to be dispensed, with the substrate held in interactive relation with the finger so as to partially rotate the finger from a designated position when no substrate is held by the table, to a selected position when a substrate is held by the table, and wherein when the finger is in the selected position it can be further rotated there from by movement of the projection as the shutter is moved to activate the fan. characterized by a rotatable finger that must be rotated by interaction with the projection of the shutter before the switch can be activated, the dispensing device further including a table to receive and hold a substrate exposed to the air stream, wherein the substrate bears an air treatment chemical to be dispensed, with the substrate held in interactive relation with the finger so as to partially rotate the finger from a designated position when no substrate is held by the table, to a selected position when a substrate is held by the table, and wherein when the finger is in the selected position it can be further rotated there from by movement of the projection as the shutter is moved to activate the fan.