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Garage Hazards

Carbon monoxide poisoning awareness

Garage Hazards


Workplace Safety Division
Directorate of Assessments and Prevention
U.S. Army Combat Readiness Center
Fort Rucker, Alabama

Industrial Scientific reports that each year about 500 people in the United States die from carbon monoxide (CO) poisoning, and over 10,000 more seek medical treatment, despite the wealth of information about its risks. According to the Occupational Safety and Health Administration, one of the most common sources of CO exposure is the internal combustion engine. The risk of CO exposure is increased when operating a gasoline-powered engine in enclosed spaces, specifically attached garages.

Carbon monoxide poisoning has been studied since at least the 1920s, when ventilation concerns in major motor vehicle tunnels were examined (Parker, 2014). Since then, many states have enacted laws regarding CO detectors. As of 2018, 27 states and the District of Colombia have adopted varying statutes regarding CO detectors. Another 11 states have helped spread awareness on CO detectors through their building codes or the adoption of the International Residential Code (National Conference of State Legislatures, 2018). 

Carbon monoxide is formed by the incomplete burning of any material containing carbon, such as natural gas, gasoline, kerosene, oil, propane and coal. Dangerous levels of CO can be produced from any fuel-burning appliance, including automobiles. When the gas builds up in enclosed spaces, people who breathe it risk being poisoned. 

With more than 274 million vehicles registered in the United States, now is not the time to become complacent with the inherent risks associated with the operation of fuel-burning automobiles (Statista, 2019). As cooler weather approaches, people may mistakenly begin to warm their cars in garages. It may be even more tempting now that remote car starters have become commonplace; however, this is never a good idea. A study by Iowa State University concluded that operating an engine in a closed building is extremely dangerous, even for short periods of time. It’s so dangerous that the study concluded it should never be done. High concentrations of CO build very quickly and an individual “may collapse before they even realize there is a problem” (Greiner, 1996). Furthermore, cold engines produce higher concentrations of CO and for longer periods of time. 

For the first two minutes of operation, an automobile engine can produce CO concentrations at 80,000 parts per million (ppm) (Greiner, 1998). The risk is compounded when the vehicle is started in an attached garage. Air typically flows into the house from an attached garage, bringing with it any CO and exposing everyone inside to unsafe fumes (Greiner, 1998). 

Is operating an engine with the garage door open acceptable? No, according to the same study, which found that CO concentrations in the garage were at 500 ppm with the garage door open after warming up a vehicle for only two minutes. Even with windows and doors open, one should never run any gasoline-powered engine, to include a power generator, inside a garage or other enclosed structure (Greiner, 1998).

The Centers for Disease Control and Prevention (CDC) recommends that every home have at least one working CO detector in the house. These detectors should be battery operated or have battery backups (2017). Since CO is slightly lighter than air, detectors should be placed higher than ground level. 

Early signs of poisoning are difficult to detect, as CO is colorless, odorless, tasteless and non-irritating (Industrial Scientific, 2018). This “silent killer” strikes quickly, catching victims off guard. People who are sleeping or who have been drinking alcohol can die before ever having symptoms of CO poisoning (National Safety Council, 2019). For more on CO poisoning symptoms, see Table 1 below.
Carbon monoxide is dangerous because it binds to hemoglobin in the blood (carboxyhemoglobin) and prevents the blood from carrying enough oxygen. Non-reversible physical damage can occur quickly when the body suffers any oxygen shortage (Industrial Scientific, 2018). Parts of the body that require a lot of oxygen, such as the heart and brain, are particularly susceptible to damage (OSHA, 2012). 

High concentrations of CO kill in less than five minutes. It will take more time for the body to be affected by lower concentrations of CO, but the risk is still tremendous. How long a person is exposed, the concentration of CO and the activity level of the person breathing it will determine the effect on the body (Berg, 1984). For more on the toxic effects of CO, see Table 2 below.

According to the CDC, if CO poisoning is suspected, the victim should immediately move into fresh air and seek medical treatment (2017). The half-life of carboxyhemoglobin in fresh air is about four hours. Medical treatment includes the administration of oxygen. If there are large amounts of CO in the bloodstream, the oxygen may be administered via a hyperbaric chamber, a pressurized oxygen device that forces the CO from the body (Greiner, 1996).

Protect yourself and your family from the risks associated with automobiles and CO poisoning. Never leave a vehicle running in an enclosed or partially enclosed space. Open the garage door before starting your vehicle and immediately back out. Additionally, know the state requirements for CO detectors where you live, and install them to alert you to the silent killer. 




  • 1 November 2019
  • Author: USACRC Editor
  • Number of views: 2405
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