Carbon Monoxide (CO) emerges as a byproduct of combustion whenever fuel is burned, and it is a common presence in households. Household appliances like gas or oil furnaces, refrigerators, clothes dryers, water heaters, fireplaces, charcoal grills, gas ranges, wood-burning stoves, and space heaters all contribute to CO emissions. Even automobile exhaust fumes contain CO, which can infiltrate homes through walls or doorways if a car is left running in an attached garage.

While proper ventilation and absence of appliance malfunctions, air pressure fluctuations, or airway blockages can usually ensure safe venting of CO to the outside, modern energy-efficient homes may face challenges. Insulation designed to retain warmth can inadvertently trap CO-polluted air throughout the year. Issues like cracked furnace heat exchangers, blocked vents, or insufficient air supply for combustion appliances can lead to back-drafting or reverse stacking, forcing contaminated air back into the home. Vigilance and proper maintenance are crucial in mitigating the risks associated with CO in residential environments.