Criminal Mischief: The Art and Science of Crime Fiction: Episode #45: Carbon Monoxide Poisoning
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From FORENSICS FOR DUMMIES:
That Sneaky Carbon Monoxide
Carbon monoxide is sneaky and deadly. When authorities find a suicide victim in her garage, sitting in a car with the engine running, they can usually chalk up that death to carbon monoxide.
Carbon monoxide is a tasteless, odorless, colorless gas that is completely undetectable by humans. It results from the incomplete combustion of carbon‐containing fuels like wood, coal, and gas. Faulty stoves, heaters, and fireplaces can fill the air with CO. Carbon monoxide poisoning kills more people trapped in fires than the fire itself does.
CO is particularly treacherous because it binds to hemoglobin, producing carboxyhemoglobin in your blood. Because carboxyhemoglobin contains no usable oxygen, cells containing this molecule can’t supply oxygen to the tissues of the body. Thus, the body’s cells become starved for oxygen. Carbon monoxide binds to hemoglobin 300 times more readily than oxygen does and thus takes oxygen’s place in the body. Your body can get very high blood levels of CO by breathing air that contains only small amounts of it. For example, breathing air that contains a carbon monoxide level as low as 0.2 percent can lead to blood CO saturations greater than 60 percent after only 30 to 45 minutes.
Most people believe that CO is toxic only in an enclosed area, but that’s just not true. People have died while working on their cars in the open air; typically, someone finds the victim lying near the car’s exhaust. Similarly, swimmers and water skiers who loiter near the dive platform on the back of an idling powerboat also run the risk of CO poisoning. Carbon monoxide’s powerful attraction to hemoglobin explains how people can succumb to CO poisoning in open areas.
The signs and symptoms of CO toxicity correlate with its concentration in the blood:
1–The normal level of CO in the blood is 1 to 3 percent, but it can be as high as 7 to 10 percent in smokers.
2–At levels of 10 to 20 percent, you experience headaches and a poor ability to concentrate on complex tasks.
3–Between 30 and 40 percent, headaches become severe and throbbing, and nausea, vomiting, faintness, and lethargy appear. Pulse and breathing rate increase noticeably.
4–Between 40 and 60 percent, the victim becomes confused, disoriented, weak, and displays extremely poor coordination.
5–Above 60 percent, coma and death arrive.
In the elderly and those individuals with heart or lung disease, levels as low as 20 percent can be lethal. Victims of car exhaust suicide or those who die from fire in an enclosed room may reach CO levels as high as 90 percent.
Autopsy findings in CO poisoning depend, in part, on carboxyhemoglobin’s bright red color. When the ME performs an autopsy on a victim of CO poisoning, the blood and internal organs often appear bright red, and this offers a clue to the possible cause of death.
Individuals who survive CO intoxication can suffer serious health problems. Carbon monoxide mostly damages the brain because it’s the organ most sensitive to a lack of oxygen. Symptoms and signs of significant brain insult may begin immediately or be delayed for several days or weeks. The most common after‐effects include chronic headaches, memory loss, blindness, confusion, disorientation, poor coordination, and hallucinations. The ME may be asked to evaluate a surviving victim if authorities suspect that the exposure was the result of a criminal act or they want documentation for a civil lawsuit.
CO Deaths From car Used as Heat Source: https://www.nbcnews.com/news/weather/two-dead-carbon-monoxide-poisoning-after-using-car-heat-texas-n1257972
PubMed: CO Poisoning Deaths is US, 1999-2012: https://pubmed.ncbi.nlm.nih.gov/26032660/
CDC: CP Poisoning: https://www.cdc.gov/dotw/carbonmonoxide/index.html
Famous People Who Died of CO Poisoning: https://www.ranker.com/list/famous-people-who-died-of-carbon-monoxide-poisoning/reference