Carbon Monoxide: It’s a Gas

Red blood cells are packed full of hemoglobin molecules, which bind oxygen in the lungs and then cart it through the arteries for distribution to the body. It’s an exquisitely beautiful system: tissues running low on oxygen build up acid, and acid weakens the oxygen-hemoglobin bond, allowing oxygen to be easily off-loaded to the tissues that need it most.

Carbon monoxide screws all of that up. It binds very tightly to the hemoglobin molecule (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1281520/) , and makes oxygen molecules do the same. The odd thing about carbon monoxide poisoning is that while the body is starving for oxygen, there is actually plenty of oxygen in the bloodstream: it just can’t be pried off the red blood cells.

The human body responds to this oxygen deprivation with symptoms such as headache, nausea and vomiting, dizziness, lethargy and a feeling of weakness. The higher the levels of carbon monoxide, the worse the symptoms—including death (arguably the worst symptom one can experience).

Carbon monoxide (CO) is a by-product of burning fuel (i.e. you won’t get it from an electric heater), so poor ventilation is a requisite. On the production side, a fire that is oxygen-starved will produce more CO; on the ventilation side, CO can accumulate if, for example, the exhaust from your gas stove is not exiting your house because the long-tailed tree rats have clogged your vent hood, again.

According to Mayo Clinic (https://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/8649) , automobiles are the most common source for CO poisoning, and the CDC (https://www.cdc.gov/co/faqs.htm) recommends that a mechanic perform an annual check of the exhaust system, since a small leak in the exhaust system can lead to a build-up of CO inside the car. And they also suggest that one should never run a car inside a garage that is attached to a house even with the garage door open.

Cigarettes produce carbon monoxide, which is a key component in the biochemical brew of smoking that causes scarring and narrowing of the blood vessels, i.e. atherosclerosis. Non-smokers have baseline CO levels of 2% or less, whereas smokers have levels up to around 9%, depending on how much they fumar.

Symptoms of CO poisoning usually don’t arise until the blood levels get to 20% or higher, but sometimes the symptoms can be disproportionately more severe than the blood level would suggest. That’s because CO blood levels fall 15% every hour you are away from the CO source; so, if it took a while for the person to get to the emergency room or clinic, they had time to exhale a portion of the CO off.

Carbon monoxide is a colorless, tasteless, odorless gas, so with winter coming on and the windows and doors closing, it’s a good time to check your fire and CO detectors.