an electronic sensor is configured to be carried by a person and to be used by the person to detect a cleanliness state of the person &# 39 ; s hands . a single unit includes the electronic sensor and a device to provide an indication of the cleanliness state of the person &# 39 ; s hands and / or a device to identify the person . a circuit that is configured to control how long after a cleanliness state of a person &# 39 ; s hands has been determined to be clean , the state is presumed no longer to be clean . a badge that includes indicia identifying a person who carries the badge , a sensor to be used to detect a cleanliness state of the person &# 39 ; s hands , and a visible indicator to indicate to other people the cleanliness state of the person &# 39 ; s hands can be used in combination .