When the alarm sounds, silence the alarm. Move everyone outside to fresh air and call for help from an outside location. If anyone is experiencing symptoms of carbon monoxide poisoning, call 911. If no one has symptoms, ventilate the building and contact a qualified service technician. Have all home equipment that is powered by fuels such as gas, wood, or petroleum products inspected by a qualified technician. Have fuel-burning heating equipment and chimneys inspected by a professional every year before cold weather sets in.