Carbon monoxide (CO) is a colorless, odorless, and tasteless gas, often called the “silent killer” because it can accumulate to hazardous levels without warning. Exposure to carbon monoxide can cause serious health issues by preventing the body’s red blood cells from carrying oxygen, leading to tissue damage and potentially death. This article identifies common sources of carbon monoxide, helping individuals understand potential risks.
Common Indoor Sources
Many fuel-burning household appliances can produce carbon monoxide, especially when not functioning correctly or lacking proper ventilation. Furnaces generate CO as a byproduct of combustion. While properly installed units vent gas outside, older or poorly maintained systems can develop cracks in heat exchangers, allowing CO to leak into the home. Gas-powered water heaters can also become CO sources if their venting systems are blocked, damaged, or improperly installed, causing combustion gases to back-draft indoors.
Gas stoves and ovens produce carbon monoxide, especially if not adequately ventilated or if burners are dirty, leading to incomplete combustion. Fireplaces, whether wood-burning or gas-fueled, are another common indoor source. CO production increases if chimneys are blocked, uncleaned, or if fuel does not burn completely. Gas clothes dryers can emit CO if their exhaust vents become obstructed, preventing the expulsion of combustion byproducts. Unvented space heaters, including kerosene or gas models, release combustion products directly into indoor air, posing a risk of CO buildup, particularly in enclosed areas.
Outdoor and Environmental Origins
Carbon monoxide can also originate from sources outside the home, contributing to ambient CO levels or posing a risk if allowed to enter. Vehicle exhaust is an external source. Idling cars in attached garages or near open windows and vents can allow dangerous CO levels to enter homes. Even with garage doors open, exhaust fumes can accumulate to hazardous concentrations.
Industrial activities, such as factories, power plants, and manufacturing processes, release carbon monoxide into the atmosphere, primarily from incomplete combustion of fossil fuels in boilers and furnaces. These emissions contribute to air pollution. Wildfires and brush fires produce substantial carbon monoxide as a byproduct of burning biomass. While often dispersed at higher altitudes, strong winds can carry CO downwards, potentially impacting air quality in populated areas.
Unexpected and Dangerous Sources
Some less obvious items, often misused indoors, present carbon monoxide hazards and are frequently associated with accidental poisonings. Portable generators, designed for outdoor use, are dangerous if operated inside a home, garage, basement, or any enclosed space. Their exhaust contains high levels of CO that can be deadly within minutes, and even open windows or doors do not provide sufficient ventilation.
Charcoal grills, intended solely for outdoor use, pose a threat if used indoors, even in a garage. Burning charcoal releases toxic CO, which can quickly build up to fatal concentrations, and fans do not prevent its accumulation. Propane or kerosene heaters, particularly unvented models not designed for indoor use, can produce carbon monoxide if combustion is incomplete or ventilation is poor. Power tools with internal combustion engines, such as pressure washers or concrete saws, used in enclosed or poorly ventilated areas, generate CO, creating a dangerous environment for operators and those nearby.