Carbon Monoxide: Air Pollution's Silent Killer

Carbon monoxide (CO) is a colourless, odourless, and deadly gas that is formed by the incomplete combustion of carbon-containing fuels such as natural gas, gasoline, or wood. It is emitted by a wide variety of combustion sources, including motor vehicles, power plants, and wildfires. CO is a common air pollutant that can cause serious health issues, including dizziness, confusion, unconsciousness, and death. CO levels are typically higher in indoor environments and in areas with heavy traffic congestion. Indoor sources of CO include gas stoves, malfunctioning or improperly vented gas appliances, and tobacco smoke. Unborn babies and people with heart conditions are at the greatest risk of experiencing health issues caused by carbon monoxide.

Incomplete combustion of fuels

Carbon monoxide is produced by the incomplete combustion of various fuels. This occurs when there is a limited oxygen supply for the reaction, and carbon monoxide and water are formed instead of carbon dioxide and water. Fuels are normally hydrocarbons – molecules made up of only hydrogen and carbon atoms. When these fuels combust, these atoms react with the oxygen in the air to form oxides. If there is plenty of oxygen, carbon will form carbon dioxide, and this is called complete combustion. However, if there is not enough oxygen, carbon can only form carbon monoxide, and this is called incomplete combustion.

Incomplete combustion is particularly dangerous as carbon monoxide is toxic and can cause death. It is a colourless, odourless gas, and very high levels can cause dizziness, confusion, unconsciousness, and even death. CO is of particular concern for people with heart disease, as it reduces oxygen delivery to the body's organs and tissues. For these people, exposure to carbon monoxide can cause chest pain, reduce their ability to exercise, and, with repeated exposure, contribute to other cardiovascular effects. Even healthy individuals can be affected by high levels of CO, potentially developing vision problems, reduced ability to work or learn, reduced manual dexterity, and difficulty performing complex tasks.

The incomplete combustion of fuels occurs in a variety of contexts, including the burning of fossil fuels, natural gas, gasoline, and wood. It is also common in motor vehicles, power plants, wildfires, and incinerators. Higher levels of CO generally occur in areas with heavy traffic congestion. Other sources of CO emissions resulting from incomplete combustion include industrial processes such as metal processing and chemical manufacturing, as well as residential wood burning and natural sources like forest fires.

The danger of carbon monoxide poisoning can be mitigated by ensuring that burners are cleaned and well-maintained and that burning fuels in enclosed spaces are always properly ventilated.

Outdoor sources of carbon monoxide

Carbon monoxide (CO) is an invisible, odourless, and colourless gas that is harmful when inhaled in large amounts. It is formed by the incomplete combustion of carbon-containing fuels, such as natural gas, gasoline, or wood. While CO poisoning is often associated with indoor spaces, there are several outdoor sources that contribute to air pollution and can have adverse health effects.

One of the major outdoor sources of CO is the burning of fossil fuels by vehicles, including cars, trucks, and boats. The emissions from these vehicles release CO into the atmosphere, particularly in urban areas with high traffic congestion. Additionally, outdoor power equipment, such as lawnmowers and generators, can also contribute to CO levels outdoors.

Another significant outdoor source of CO is the operation of industrial facilities and power plants. These facilities often burn fossil fuels, such as coal or natural gas, to generate electricity, releasing CO into the atmosphere. Wildfires and incinerators also produce CO emissions, especially in regions where they are prevalent.

Certain outdoor recreational activities can also generate CO. For example, camping, fishing, hunting, and boating may involve the use of camp stoves, charcoal grills, fuel-burning lanterns, and generators, all of which produce CO. It is important to use these items in well-ventilated areas and avoid using them inside tents, RVs, or cabins to prevent dangerous CO buildup.

While outdoor air pollution from CO is a concern, it is worth noting that drastic reductions in emissions from space heating and traffic have been achieved in recent decades, leading to improved air quality in urban areas. Additionally, the EPA in the United States sets and reviews standards for CO in outdoor air to ensure that it is maintained at safe levels.

Indoor sources of carbon monoxide

Carbon monoxide (CO) is an invisible, odourless, and tasteless gas formed by the incomplete combustion of fuels. When people are exposed to CO gas, the CO molecules will displace the oxygen in their bodies, leading to poisoning. Hundreds of people die accidentally every year from CO poisoning caused by malfunctioning or improperly used fuel-burning appliances.

• Furnaces: Most homes have a furnace to provide central heating. Since most furnaces use natural gas to produce heat, carbon monoxide can be a risk. Over time, and without regular maintenance, the heat exchanger can become cracked or dirty and may leak carbon monoxide into the house.
• Gas dryers: Gas dryers need adequate ventilation to prevent carbon monoxide. When there is not enough oxygen for combustion, the result is carbon monoxide. Vents that are not cleaned regularly can get clogged with lint or other debris, which can easily start a fire.
• Tobacco smoke: Tobacco smoke can be a major source of indoor carbon monoxide exposure.
• Incense burning: Incense burning in homes and public buildings can be a source of carbon monoxide exposure.
• Gas stoves, ovens, and grills: Gas stoves, ovens, and grills can be sources of carbon monoxide if they are incorrectly installed, poorly maintained, or poorly ventilated.
• Generators: Unsafe use of generators can cause carbon monoxide poisoning. Most generators run on fuel sources like gasoline or propane, which produce carbon monoxide when burned.
• Vehicles: Exhaust from vehicles operating in attached garages can be a source of indoor carbon monoxide exposure.
• Fireplaces: Poorly ventilated or clogged chimneys and wood-burning fireplaces can vent carbon monoxide into indoor spaces.

Health effects of carbon monoxide

Carbon monoxide (CO) is a colourless, odourless, and dangerous gas that results from the incomplete combustion of carbon-containing fuels, such as natural gas, gasoline, or wood. It is emitted by a wide range of combustion sources, including motor vehicles, power plants, wildfires, and incinerators. CO is harmful as it binds to haemoglobin in the blood, reducing the blood's ability to carry oxygen. This interference with oxygen delivery to the body's organs can cause a range of health issues, and even death.

The most common effects of CO exposure are fatigue, headaches, confusion, dizziness, upset stomach, vomiting, and chest pain. These symptoms are often described as "flu-like", and inadequate oxygen delivery to the brain can also lead to a person experiencing confusion and a lack of coordination. For people with cardiovascular disease, short-term exposure to CO can further reduce their body's ability to respond to the increased oxygen demands of exercise, exertion, or stress. Inadequate oxygen delivery to the heart muscle can cause chest pain and decreased exercise tolerance.

CO poisoning is a life-threatening emergency that can cause brain damage and even death if inhaled in high enough concentrations. It is particularly dangerous because it is impossible to detect without a CO detector, and people who are sleeping or drunk may die from CO poisoning before they experience any symptoms. Unborn babies, infants, elderly people, and those with anaemia or a history of heart or respiratory disease are more likely to experience adverse health effects from elevated levels of CO exposure.

To prevent CO poisoning, it is important to ensure proper ventilation and to avoid using fuel-burning appliances in enclosed spaces. Regular maintenance and inspections of fuel-burning appliances, chimneys, and exhaust systems can also help reduce the risk of CO buildup. Additionally, installing CO detectors near sleeping areas and other strategic locations in the home is crucial for early detection and warning.

Carbon monoxide detection and prevention

Carbon monoxide (CO) is a colourless, odourless, and poisonous gas that is formed by the incomplete combustion of carbon-containing fuels, such as natural gas, gasoline, or wood. It is emitted by a wide range of sources, including motor vehicles, power plants, wildfires, and indoor sources such as gas stoves, fireplaces, and tobacco smoke. Due to its invisible and undetectable nature, carbon monoxide is often referred to as the "silent" or "invisible killer".

To protect against carbon monoxide poisoning, it is crucial to have working carbon monoxide detectors installed in your home or enclosed spaces. These detectors are designed to sound an alarm when dangerous levels of carbon monoxide are present. The alarms have concentration-time functions, meaning they do not sound an alarm immediately unless the concentration is extremely high, to prevent false alarms from brief bursts of carbon monoxide.

There are four types of sensors available for carbon monoxide detection, varying in cost, accuracy, and speed of response. The most affordable option is a coloured chemical pad that changes colour upon reaction with carbon monoxide. However, it only provides a qualitative warning and offers the lowest level of protection. Other types of sensors include biomimetic sensors, which function similarly to hemoglobin, darkening in the presence of CO and proportional to the amount present.

In addition to detectors, prevention and safety measures are essential. The US Fire Administration and the US Environmental Protection Agency (EPA) provide safety messages and materials to increase community awareness about the dangers of carbon monoxide. It is recommended to install and maintain CO alarms inside your home, particularly in central locations outside each separate sleeping area and on every level. For portable generators, they should be used outdoors in well-ventilated areas away from doors, windows, and vents.

Furthermore, proper maintenance and use of fuel-burning appliances are crucial. Keep vents for dryers, furnaces, stoves, and fireplaces clear of snow and debris. Ensure that fuel-burning appliances, such as furnaces, heaters, or generators, are working and vented properly. Be cautious of idling cars in garages, as they can also contribute to carbon monoxide build-up.

Frequently asked questions