Carbon Monoxide (CO) is a toxic gas created by the incomplete burning of carbon-containing fuels such as wood, oil, natural gas, gasoline, and propane. Often called the silent killer, CO is dangerous precisely because it lacks any sensory characteristics that would alert a person to its presence.
Carbon Monoxide is Odorless
Carbon monoxide is entirely undetectable by human senses, possessing no odor, color, or taste. This characteristic allows lethal concentrations to build up in enclosed spaces without warning. The gas is produced any time a fuel-burning appliance, engine, or fire is operating without proper ventilation.
The confusion regarding the “rotten egg” smell stems from the distinct odor associated with natural gas leaks. Natural gas is naturally odorless, just like carbon monoxide. Utility companies intentionally add a chemical called mercaptan to natural gas to give it a strong, sulfuric, rotten-egg smell for safety. This deliberate additive ensures that a natural gas leak is immediately noticeable, but this foul odor has no relation to the presence of carbon monoxide.
Recognizing the Physical Signs of Poisoning
Since the gas cannot be detected by smell, the first indications of carbon monoxide exposure are physical symptoms. These early signs often mimic the flu, including a dull headache, dizziness, weakness, and nausea. This similarity to a common illness can cause people to ignore the initial warnings, delaying their escape from the contaminated environment.
As exposure continues, the symptoms become more severe, progressing to vomiting, confusion, blurred vision, and loss of muscle control. The toxic effect occurs because CO molecules enter the bloodstream and bind to hemoglobin, the oxygen-carrying protein in red blood cells. Carbon monoxide has an affinity for hemoglobin that is over 200 times greater than oxygen, quickly forming carboxyhemoglobin and effectively suffocating the body’s tissues. High-level exposure can lead to loss of consciousness, seizures, and death, sometimes within minutes.
Preventing Exposure Through Detection and Source Management
The only reliable method of detection in a home is through certified carbon monoxide alarms. These devices should be installed on every level of the home, including the basement, and particularly near all sleeping areas. Placing detectors outside bedrooms ensures that occupants will be alerted to a problem even while they are asleep.
Common household sources include improperly vented or malfunctioning fuel-burning appliances such as furnaces, gas water heaters, and gas stoves. Other sources are fireplaces, portable generators, and vehicles running in an attached garage. Regular professional maintenance of heating systems and flues is necessary to ensure proper combustion and venting. Never operate a grill, generator, or car inside a garage or enclosed space, as the gas can quickly build to lethal concentrations.