A person-carried portable transceiver unit informs a remote home base of the person's activities, location, and/or exposure to a toxic gas. The person uses the portable transceiver unit for sending different predetermined chosen text messages to the home base. In some examples, the particular message is chosen by the number of times the person sequentially triggers a single switch on the unit. In cases where the single switch is a pushbutton, pressing the button three times, for example, could indicate the person is heading to a worksite, and pressing the button four times could indicate the person arrived at the worksite. For the home base to determine whether the person is still conscious and alert while at the worksite, the home base periodically sends to the portable unit reminder signals that prompt the person for a certain response, such as, for example, the person pressing the button twice in succession.