Go indoors and keep clear of the windows. Keep emergency numbers for police and fire departments near your phone. Make sure that at least one smoke detector is placed on every floor of your home. Locate detectors on the ceiling away from air vents and near bedrooms. Test your detector every few months to ensure it's working.
Carbon monoxide is a poisonous gas.
It is particularly dangerous because it is colorless and odorless. If fuel is burned without an adequate supply of air, carbon monoxide gas can be produced. Be especially sure there is proper ventilation when fireplaces, wood stoves or other air consuming devices are operated at the same time as your regular heating system. Never use a charcoal grill in the house. Consider purchasing a CO detector.