Ethyl alcohol sensor and method of use

An ethanol sensing unit (10) and a method of using, wherein the unit (10) is particularly suitable for use in a confined environment (16) such as the passenger compartment (16) of a passenger vehicle (18). The sensing unit (10) comprises a device (12,20) for collecting ethanol vapors while the device (12,20) is at a first temperature, a device (12,24) for heating the collecting device (12,20) to a second temperature higher than the first temperature so as to release ethanol vapors from the collecting device (12,20), and a device (26,28) for sensing the ethanol vapors released from the collecting device (12,20) when heated by the heating device (24). The sensing unit (10) is also adapted to delay the operation of the heating device (24) until a period of time sufficient for the collecting device (12,20) to adsorb ethanol vapors from air contained in the confined environment (16).