Call 112 or your local gas emergency service immediately and move to fresh air. Either go outdoors or go near open doors or windows. Do a head count to check that all persons are accounted for. Do not re-enter the premises nor move away from an open door/window until emergency service responders have arrived, the premises have been aired out, and your alarm is in its normal condition. If your alarm reactivates within a 24 hour period, repeat steps 1-3 and call a qualified appliance technician to investigate for sources of carbon monoxide (CO) from fuel burning equipment and appliances, and inspect for proper operation of this equipment. Any problems identified should be corrected immediately. Make sure that motor vehicles are not, and have not been, operating in an attached garage or adjacent to the residence. IMPORTANT: Never Ignore the Sound of an Alarm! WARNING! Activation of your CO alarm indicates the presence of Carbon Monoxide which can KILL YOU.