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Carbon Monoxide (CO) Poisoning As a Method of Suicide

The following information reflects material I have researched from a variety of sources. Many of the web-based sources are referenced by their URL at the end of this document.

Part One: Life, Death and Gas

Animal life depends upon oxygen. When we lose the availability of oxygen we asphyxiate (suffocate). Common methods of asphyxia include drowning, strangulation, obstructed airways, etc. Asphyxia can also be caused by the absence of oxygen in an environment where we are free to breathe, inside a plastic bag, for example.

We produce carbon dioxide (CO2) as a waste product. The body is very sensitive to high levels of CO2 and when present will begin an involuntary reaction that includes panic and increased rate of breathing. You can try this with a plastic bag over your head. In a minute or two you will become acutely aware that you need to breathe fresh air, even though you have yet to experience oxygen deprivation, your body has become aware of the high levels of CO2 and is automatically alerting you to seek fresher air.

Sometimes gases can replace oxygen and induce death without causing a CO2 panic reaction. Some of these gases are bioreactive gases and some are innocuous gases.

Innocuous gases, such as nitrogen (which makes up about 70% of the atmosphere) do not cause the asphyxia panic that CO2 does. Replacing oxygen with nitrogen will cause death, but I do not know much about this.

Some bioreactive gases, such as nitrous oxide, produce specific reactions that are well perceived at the time of poisoning. Nitrous oxide is widely used as an analgesic in dentistry, it is commonly known as laughing gas. It produces a sense of euphoria and it can easily be lethal. Another gas that is bioreactive is Carbon Monoxide (CO). CO is commonly available, easily produced, colorless, tasteless and odorless. It can produce some vague, flu-like symptoms before causing death. The order of symptoms that might occur as someone dies of CO poisoning are:

  1. Headache
  2. Dizziness
  3. Upset Stomach
  4. Clumsiness
  5. Drowsiness
  6. Brain Damage
  7. Death

Part Two: Carbon Monoxide and Suicide:

The three principal advantages for CO poisoning for the suicide are:

  1. Availability
  2. Lack of discomfort
  3. Speed

Carbon monoxide is produced when anything ---ANYTHING--- is burned incompletely. (Virtually all combustion is somewhat incomplete, so it is safe to say that anytime you burn anything you produce CO.) The most common sources of accidental and suicidal deaths by CO are automobiles and furnaces/hot water heaters, but CO can be used for suicide wherever there is (1) combustion and (2) a contained area in which to collect the CO. Other sources of CO that have caused poison deaths are fireplaces, gas clothes dryers, ovens, stoves, space heaters, braziers, charcoal briquettes, etc.

The distribution of CO in a space depends upon a variety of factors. Your goal is to have the highest possible partial pressure of CO, that is have CO be as large a part of the total gases. It is best to plan on venting a space at a point farthest away from the source. A single vent (low pressure) away from your source (high pressure). The effect of CO is increased as heat and humidity are increased.

Concentrations of CO of 800 parts per million (ppm) can be lethal after three hours. At 6,400 ppm death occurs within 30 minutes or less. CO is better than oxygen at binding with the hemoglobin in our red blood cells, hemoglobin is about 250 times more likely to bind with CO than with oxygen. When CO and hemoglobin combine they produce carboxyhemoglobin. This has a half life of five hours and concentrations of about 50% (half of the hemoglobin is bound up as carboxyhemoglobin) produce death. According to the Haldane Equation, the amount of carboxyhemoglobin, compared to hemoglobin, is about 210 times the amount of CO, compared to oxygen. So, levels of one quarter of one percent (.25%) of CO in the air will produce lethal levels (210 times .0025 = 52.5%) and higher levels will produce death more quickly.

Perhaps it is simpler to say that it is fairly easy to produce a lethal level of CO.

Part Three: Choosing a Source for CO:

Your best bet for producing lethal levels of CO might be burning a charcoal grill in a well insulated garage or room. Start it out-of-doors and burn it till you have a good bed of glowing coals. Then move it indoors and close up the space, leaving only one small vent open, away from the charcoal Heat and humidity speed up the poisoning process.

I have constructed a diverter for the flue from my hot water heater so that it will vent into my living room. My hot water heater burns natural gas which produces a pleasant (for me) smelling exhaust and I can use this method to die inside my home with only a small risk of a fire.

Automobiles (or any devices with gas or diesel engines) produce adequate quantities of CO. Diverting the exhaust into the passenger cabin of a car gives one the opportunity to die in any variety of places, including a favorite scenic lookout, without putting others at risk. Since 1975 in the US, and 1993 in the UK, passenger cars have been equipped with required catalytic converters. The goal is to reduce the emission of CO, oxides of nitrogen and unburned hydrocarbons. Depending upon the car, this is accomplished by balancing the tuning of the carburation, use of catalysts in the catalytic converter and injection of oxygen into the exhaust. The effectiveness of this system depends upon the car being well tuned and the oxygen sensor being in good working order. Increasing the carburetor mixture to "rich" or applying choke by operating a manual choke or by defeating the automatic choke, will increase the amount of CO in the exhaust. Defeating the oxygen sensor (which is designed to fail at 50,000 miles) or removing the catalytic converter will also increase the CO content. In any event, a well-tuned car with emissions controls in place will still produce adequate levels of CO to cause death, but it will take longer. A cold engine will always produce a higher concentration of CO than a hot engine.

With most methods you can allow the CO to build up, then enter the space after it has reached high concentrations.

Whatever method you choose it should be easy to predict the length of time it takes to produce and collect a lethal level of CO. You can use CO detectors (with digital readouts), readily available at any hardware or home supply store, to measure the level of CO accumulated over a period of time and the rate of increase. It is then easy to extrapolate how long it will take to build up to the concentration you desire.

Accessories for Death by CO Poisoning

In about half the cases of suicide by CO (in automobiles) it was determined that alcohol and/or drugs were present. You may be able to predict, but you will hardly be sure, how long it will take before you become unconscious. During that time there may be other exhaust fumes, humidity or warm temperatures. It seems to make sense to have some drinks, drugs, music, etc. available for the minutes it will take to become unaware.

Reference URL's:
The Wayne State University School of Medicine Carbon Monoxide Headquarters home page. Wayne State University is a major teaching and research institution, this site is wonderfully complete, pages on the history of CO research, sources, actions in the body, formulas for uptake, links; this is THE comprehensive site for a thorough investigation of CO.
Wayne State University School of Medicine Epidemiological Study of all US CO deaths 1979-1988
Wayne State University School of Medicine This is an index to lay articles on carbon monoxide in the home, written by Dr. David Penney. They were published in the Mirror newspapers during the past year.
Wayne State University School of Medicine For those concerned that a vehicle equipped with a catalytic converter will not supply a lethal dose of CO, visit this site. It includes models, figures and bibliographies of studies.
Wayne State University School of Medicine On this page you can read that,"[a]lso, current catalytic converters still permit exhaust gases to contain lethal CO concentrations. "
The Carbon Monoxide FAQ site. All the information you would need to plan a CO suicide and little more. Lay language, nice chart of PPM concentrations and symptoms.
Iowa State University has a more compact with fewer formulas and more plain language articles. Has a page on charcoal briquets that is almost a "how-to" for the suicidal. Many pages on home heating and CO.
In British English, and a bit academic, but if you call it "Town gas" you might want to check it out. Focus is on accidental death, but suicide is discussed on page 3 of the site where it says suicide by car is depressingly easy.
CO ALERT! A lay language site, easily navigated
A confusing site on auto emissions and CO published by the US EPA. I include this site with some misgivings. The EPA is manipulating figures to give the appearance that car exhaust is safe. It is safer, but it contains quite lethal levels of CO. Read this page carefully and remember that figures don't lie, but liars figure. Use the information in other sites to interpret the EPA claims.
Manufacturers of CO detectors, this site gives basic information of home sources of CO and describes how their sensors work and how they should be placed for good measurement. Good information for those who want to test their system using a CO detector.

-Doug J.
Last update: Saturday, August 1, 2002 08:10

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