Carbon monoxide (CO) is a highly toxic gas that forms from the incomplete burning of carbon-containing fuels such as gasoline, wood, natural gas, and charcoal. This invisible, odorless, and tasteless nature has earned it the nickname “the silent killer.” The gas is a by-product of common household appliances, like furnaces, water heaters, and stoves, when they malfunction or are improperly vented. Understanding how this substance behaves in an enclosed space is a significant part of protecting a home and its occupants from poisoning.
The Physical Properties of Carbon Monoxide Gas
The core question about whether carbon monoxide rises or falls can be answered by comparing its molecular weight to that of ambient air. Carbon monoxide (28.01 grams per mole) is technically lighter than air (28.97 g/mol), but the difference is minimal, less than 3% in density. This marginal difference becomes almost entirely irrelevant in the dynamic conditions of a typical home or building, as the slight density variation is easily overcome by minor air currents and temperature fluctuations. Therefore, relying on the physical property of CO being negligibly lighter than air for safety planning would be a mistake.
How Carbon Monoxide Moves Inside a Building
In the dynamic environment of a home, the movement of carbon monoxide is dictated by airflow and temperature gradients. When CO is produced by a malfunctioning fuel-burning appliance, it is typically hot, causing it to rise initially due to thermal buoyancy and convection currents. As the newly generated CO moves away from the heat source, it begins to cool and mix rapidly with the ambient air. Due to the gas’s near-identical density to air, it diffuses quickly and evenly throughout the entire volume of the room. Air movement, such as drafts and forced-air heating, ensures this uniform distribution, resulting in a homogeneous mixture where dangerous levels of CO can be present anywhere.
Best Locations for CO Detectors
Given that carbon monoxide rapidly mixes and spreads uniformly throughout a space, the placement of a detector is primarily about ensuring occupant safety. Safety officials recommend installing detectors in several key locations:
- Near sleeping areas, where they can wake occupants.
- On every level of the home, including the basement.
- Near or over any attached garage.
The optimal mounting height is a subject of variation, though many manufacturers suggest a wall placement at eye level, around five feet from the floor. Studies have shown that the height of the detector does not significantly impact its ability to detect the gas. The most important factor is having working detectors positioned where their alarm can be heard by all occupants. To prevent false alarms, detectors should be installed at least 15 feet away from any fuel-burning appliance.
Recognizing Acute Carbon Monoxide Poisoning
Exposure to high concentrations of carbon monoxide leads to acute poisoning, which can quickly become life-threatening. The gas enters the bloodstream and binds strongly to hemoglobin, the molecule in red blood cells that normally carries oxygen. This process forms carboxyhemoglobin, which effectively prevents the blood from transporting oxygen to the body’s tissues and organs.
The initial symptoms of acute CO poisoning are often vague and resemble those of the common flu, including headache, dizziness, nausea, and general weakness. As exposure continues, symptoms worsen to include confusion, chest pain, impaired coordination, and eventually loss of consciousness. If poisoning is suspected, the affected individual must immediately move to fresh air and seek emergency medical assistance.