Carbon monoxide (CO) is known widely as “The Silent Killer” because it is colorless, odorless, and tasteless, making it an extremely dangerous household hazard. It results from the incomplete burning of various carbon-containing fuels in everyday appliances and vehicles. The primary danger of CO is its ability to deprive the body of oxygen, leading to serious illness or death. Understanding the properties of CO and the appropriate placement of detectors is paramount to mitigating this invisible risk.
The Chemical Nature of Carbon Monoxide
Carbon monoxide (CO) is a simple compound formed by one carbon atom and one oxygen atom. The life-threatening nature of this molecule stems from its intense affinity for hemoglobin, the protein responsible for transporting oxygen in the blood. Hemoglobin binds to carbon monoxide approximately 200 to 250 times more tightly than it binds to oxygen.
When inhaled, CO rapidly displaces oxygen in the red blood cells, forming a highly stable compound called carboxyhemoglobin (COHb). This process significantly reduces the blood’s capacity to deliver oxygen to the body’s tissues and organs, initiating a condition known as hypoxia. Organs with high oxygen demands, such as the brain and the heart, are particularly susceptible to damage from this oxygen deprivation. Furthermore, CO also affects cellular respiration directly by binding to proteins, disrupting the cells’ ability to use any available oxygen.
Why CO Does Not Significantly Rise or Fall
The question of whether carbon monoxide gas rises or falls depends on its molecular weight compared to ambient air. CO has a molecular weight of approximately 28.01 grams per mole (g/mol), while air averages about 28.97 g/mol.
Because CO is only slightly lighter than air, it does not reliably rise to the ceiling like smoke or sink to the floor like propane. The density difference is minimal, so CO mixes readily and relatively evenly with the surrounding air. Within a home, air currents and temperature gradients completely override this minor difference in molecular weight.
Air circulation caused by forced-air heating and cooling systems, open windows, and simple convection currents are the dominant factors dictating how CO distributes within a room. If the source of the CO leak is a hot appliance, the heated gas may initially rise with the warm air, but it will quickly cool and disperse throughout the entire enclosed space. Therefore, the gas itself does not favor any specific height within a room, making the concern about CO rising or sinking largely irrelevant for detector placement.
Critical Sources of Carbon Monoxide Generation
Carbon monoxide is a byproduct of incomplete combustion, occurring whenever fuel is burned without a sufficient supply of oxygen. Numerous common household devices and engines can produce dangerous levels of this gas. Malfunctioning or poorly maintained fuel-burning appliances are the most frequent causes of indoor CO buildup.
Specific appliances that pose a risk include gas stoves, ovens, water heaters, and furnaces. Blocked chimneys, dirty flues, or improperly vented gas fireplaces can also prevent the gas from safely escaping the home. Beyond fixed appliances, portable sources like gasoline-powered generators, charcoal grills, and power tools must never be operated inside a garage or enclosed space. Even a vehicle left idling in an attached garage can quickly allow exhaust fumes to seep into the living areas of the house.
Detector Placement Based on Gas Dispersion
Since carbon monoxide mixes uniformly with air, detector placement is not rigidly dictated by the gas’s density, but rather by maximizing the chance of detection near sleeping areas. The most important guideline is to install detectors on every level of the home, including the basement. Placing a detector outside each separate sleeping area is highly recommended to ensure occupants are awakened by an alarm.
While CO alarms can be placed at any height, recommendations often suggest mounting them on the wall about five feet above the floor or at eye level. Some manufacturers suggest placement at knee level, particularly near beds, to protect sleeping occupants. Detectors should be installed at least 15 feet away from fuel-burning appliances, such as a furnace or stove, to prevent false alarms from trace amounts of CO produced during normal operation. Avoid installing units in direct sunlight, near open windows, or in highly humid areas like bathrooms, as these conditions can interfere with the sensor’s function.
Immediate Health Impact and Emergency Protocol
The signs of carbon monoxide poisoning are often non-specific and can easily be mistaken for common illnesses like the flu or food poisoning. Early symptoms from mild exposure frequently include a mild headache, dizziness, nausea, and general weakness. As exposure levels rise, symptoms progress to moderate effects like severe headache, mental confusion, loss of muscle coordination, and chest pain.
Severe poisoning can quickly lead to loss of consciousness, seizures, respiratory failure, and death. If a CO detector sounds an alarm or if symptoms are suspected, the immediate action is to evacuate the premises and move to fresh air outdoors. Never try to locate the source of the gas or attempt to ventilate the home before leaving. Once safely outside, call emergency services, such as 911 or the local equivalent, and seek prompt medical attention to confirm exposure.