North Tahoe Fire and Meeks Bay Fire urge residents to check the date on the back of their Carbon Monoxide alarms, as many units expire this year and must be replaced. Poisonings from carbon monoxide increase during cold weather as families rely on gas, oil and coal burning appliances for heat, and a working CO alarm is a life-saving device. Carbon Monoxide is the leading cause of accidental poisoning deaths in America, not related to drugs.