An occupancy alarm system can be integrated into a motor vehicle or can be portable. The occupancy alarm system may be programmed to communicate with a program within a logic unit of the on-board computer within the vehicle or a cellular telephone or other wireless logic device so that if the driver's door is open and the engine is turned off but there still is an occupant in the motor vehicle, an alarm is immediately triggered. The GPS coordinates of the motor vehicle or the cellular telephone or other wireless device may be communicated to a remote location service or a local emergency center as part of the alarm. The occupancy sensor may be mounted on the occupant or on the restraint system, and may interact with an ambient temperature sensor and an alarm, both of which may be integrated into a motor vehicle, to indicate that a dangerous condition exists for an occupant within the motor vehicle. The occupancy sensor, the ambient temperature monitor, and the alarm may further be integrated together for a portable alarm system or may be mounted or otherwise integrated onto a portable restraint system. The occupancy alarm system may provide an interface and an override such that when the occupant remains in a potentially hazardous environment, that state is communicated via the interface and, if monitored by a responsible adult, the alarm can be overridden.