Carbon Monoxide Safety
It’s cold outside! So batten down the hatches, but beware of carbon monoxide
February 13, 2020
By: Brenda Wiederkehr, Access Compliance
It’s wintertime, and particularly in the north, we close the windows and doors, creating a microenvironment to warm up and stay comfortable. Some people heat with electricity, which runs the risk of further drying the already dry winter air. However, most places stay warm by burning products. Most of the time, these items are hydrocarbons such as petroleum-derived products like coal, oil, or gas, or in the form of renewable fuels such as wood.
Usually, if hydrocarbon fuels are burned with enough oxygen and at a high enough temperature, the combustion products are water and carbon dioxide. In fact, carbon dioxide, is a by-product of our human internal processing of hydrocarbons in the breakdown of food. We also use oxygen and produce carbon dioxide and water; which we exhale. If carbon dioxide builds up in our body, (for any variety of reasons), it has a narcotic effect, meaning that it can induce narcosis or sleep and acts like an anesthetic gas. Fortunately, our brains have sensors which regulate our breathing rate and volume of breathing, to combat changes in carbon dioxide levels.
But if the combustion process is done inefficiently; if there is not enough oxygen or the temperature is too low, instead of carbon dioxide, the combustion produces carbon monoxide. We do produce small amounts of carbon monoxide in our body, and we are learning that this has a beneficial effect in modulating certain cellular functions. When this colorless, odorless gas moves in our bloodstream, it binds to the same chemical that transports oxygen from our lungs to our body’s cells, hemoglobin. A hemoglobin molecule has four receptors, which can hold four oxygen molecules. Carbon monoxide, which can also bind to these sites, competes with oxygen. When hemoglobin has carbon monoxide attached to it, it is called carboxyhemoglobin, or COHb. The average level of carboxyhemoglobin in our population is 0 to 3% of all hemoglobin molecules. Since cigarettes involve the smoking of leaves at a relatively low temperature, cigarette smokers may have elevated blood levels of carboxyhemoglobin. A pack-a-day smoker can have a 3 to 6% COHb level in the blood, two packs a day, 6 to 10%, and three packs a day, as much as 20%. Unfortunately, carbon monoxide holds on to those binding sites much tighter than oxygen and can prevent oxygen from being transported from our lungs to our body’s tissue cells. This results in our body being starved of oxygen which can lead to asphyxiation.
Levels of carboxyhemoglobin and their symptoms:
- 10-20% - Headaches, usually over the brow or frontal location, and nausea can occur. In fact, unexplained headaches in several people can often be the first signs of a problem in a worksite.
- Over 20% - Can cause impaired judgement, dizziness, difficulty concentrating and muscular weakness.
- Over 30% - Can cause shortness of breath with exertion, confusion and, in patients with coronary heart disease, may cause chest pain. (Methylene chloride, a common industrial solvent, is metabolized in the body to carbon monoxide and can cause heart issues as well as the other symptoms listed.)
- Higher levels - Can trigger coma, seizures, loss of consciousness and death. (Think of people who commit suicide by staying in a running vehicle inside a closed garage.)
In a work environment, anytime combustion is taking place, there is a risk for carbon monoxide production. One of the best engineering controls is dilution by supplying fresh air or venting air from combustion to the outside. As such, if you are working on a running motor vehicle in your garage, venting the exhaust to the outside makes sense. Improperly vented furnaces, fireplaces and grills can all create a risk of carbon monoxide poisoning. In fact, wherever there is combustion, there is a risk, and winter is a risk factor when we shut the windows and doors and turn up the heat.
Here are some carbon monoxide safety tips:
- Use carbon monoxide detectors.
- Watch for symptoms where any combustion is taking place.
- Call the fire department to check if carbon monoxide levels may be elevated.
- Use ventilation and other engineering controls if carbon monoxide production risk is present.
- Evacuate the space and seek fresh air if elevated levels are assumed.
- Seek medical assessment and care if symptoms arise.