In an example embodiment, an automatic warning system that warns users of personal mobile devices (such as cellular telephones and portable music players) when they enter or are near the threshold of a hazardous area while using their mobile device. In an example embodiment, the mobile device is automatically paused upon entering a street and resumes when the user has crossed the street. In a cellular telephone embodiment, calls are automatically put on hold upon entering the hazardous area, optionally the other parties to the call are informed of the reason for the hold, and the call is automatically resumed when all parties have left the hazardous area.