Carbon Monoxide: A Deadly Poison and a Neurotransmitter

Updated on March 26, 2017
AliciaC profile image

Linda Crampton is a writer and teacher with a first class honors degree in biology. She often writes about the scientific basis of disease.

A headache is one symptom of carbon monoxide poisoning.
A headache is one symptom of carbon monoxide poisoning. | Source

A Potentially Deadly Poison

Carbon monoxide in the environment is a deadly poison that kills hundreds of people in North America every year. Unlike some poisonous gases, carbon monoxide is produced by devices that we have in our homes as well as by industrial processes. It's a colorless, odorless, and tasteless gas and an insidious poison. We may not realize that we are being poisoned by carbon monoxide, since one of its effects is to make us confused and sleepy.

Strangely, this very toxic gas is a normal component of our bodies, where it's present in tiny quantities. It plays an important role in our nervous system and acts as a signaling molecule. Signaling molecules carry messages within or between cells or from one part of the body to another. A signaling molecule works by triggering a specific effect when it reaches its new location.

The chemical formula for carbon monoxide is CO. It's a simple molecule that is made of one carbon atom and one oxygen atom. This simple molecule can have big effects, however, depending on its concentration.

Gas stoves may produce carbon monoxide.
Gas stoves may produce carbon monoxide. | Source

Carbon monoxide is produced by the incomplete combustion of a fuel. Any device that burns gas, oil, kerosene, coal, charcoal, or wood can produce carbon monoxide.

Sources of Carbon Monoxide

Devices that may release CO in and around a home include furnaces, water heaters, gas stoves, propane space heaters, portable generators, charcoal grills, car engines, and fireplaces. Gasoline-powered lawn mowers, leaf-blowers, weed trimmers, chain saws, and snow blowers are also potential sources of CO.

Unfortunately, every year some people who have tried to keep warm in winter have died of carbon monoxide poisoning. Space heaters and stoves are frequently responsible for these deaths, which usually occur during power failures. Propane space heaters should never be used indoors and a gas stove should never be left on to warm a home.

It's a good idea to plan how to keep warm before a potential power failure occurs. If you have elderly acquaintances, you might want to help them prepare for a power failure. It would also be a good idea to visit them when there is no power to see how they're doing. Elderly people and babies are much more susceptible to health problems in cold temperatures than people of other ages.

A Health and Safety Video About CO

Why Is Inhaled CO Dangerous?

Our red blood cells contain a protein called hemoglobin. Hemoglobin's function is to transport oxygen from the lungs to the body's tissue cells, which use the oxygen to produce energy.

Carbon monoxide joins to hemoglobin, producing a substance known as carboxyhemoglobin. Carboxyhemoglobin can't carry as much oxygen as normal hemoglobin. The carbon monoxide also causes the hemoglobin to hold on to the oxygen molecules that have managed to join to it very tightly, preventing them from being released to the cells.

Researchers think that inhaled carbon monoxide hurts us in other ways besides blocking a cell's oxygen supply. It joins to myoglobin, a protein in muscle. This may cause muscle weakness. Carbon monoxide may also affect the functioning of the mitochondria, the structures in cells that produce the energy which we need.

According to the CDC (Centers for Disease Control and Prevention), in the United States between 400 and 500 people die from CO poisoning every year. In addition, more than 20,000 people need to visit the emergency department of a hospital due to CO exposure and more than 4,000 people need to be hospitalized.

Shortness of breath may be a symptom of carbon monoxide poisoning.
Shortness of breath may be a symptom of carbon monoxide poisoning. | Source

Possible Symptoms of Carbon Monoxide Poisoning

The symptoms of carbon monoxide poisoning may at first mimic the effects of the flu or other disorders. If an affected person stays in the dangerous environment they may become confused and fatigued. At this stage it may be hard for someone to voluntarily evacuate from the dangerous area. CO is especially dangerous for people who are already asleep.

The most common symptoms of carbon monoxide poisoning are as follows:

  • headache
  • dizziness
  • nausea
  • vomiting
  • weakness
  • chest pain
  • shortness of breath
  • confusion
  • fatigue
  • unconsciousness

These symptoms can be caused by other health problems, too, but they may indicate the present of carbon monoxide in the air.

A person who is or may be suffering from carbon monoxide poisoning needs to be removed to an atmosphere with fresh air. The rescuer should quickly open doors and windows before they help someone. The patient may need to receive supplemental oxygen. Even if the patient apparently recovers, they should be taken to a hospital.

CO Poisoning

Preventing Carbon Monoxide Poisoning

Carbon monoxide poisoning may have devastating consequences, but it can be prevented. The most important precautionary steps are to use equipment in safe conditions and to have working carbon monoxide detectors in the home. Here are some safety tips.

  • Place a CO detector on every floor of your home, especially near sleeping areas.
  • Make sure that detectors that are connected to an electrical outlet have a battery backup.
  • Replace the batteries in detectors regularly on easily remembered dates, such as family birthdays or the days when clock times change.
  • Get equipment such as furnaces and water heaters serviced once a year.
  • Make sure that devices such as stoves and fireplaces are vented.
  • Get chimneys cleaned regularly.
  • Don't leave a car running in a garage, even when the garage door is open.
  • Don't turn on gas-powered equipment such as chain saws in enclosed spaces.
  • Don't turn on generators in or near a home.
  • Never use a propane or kerosene space heater or a charcoal grill indoors.

A carbon monoxide detector and alarm
A carbon monoxide detector and alarm | Source

A Carbon Monoxide Detector Poll

Do you have carbon monoxide detectors in your home?

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A synapse is the region where one neuron ends and another begins.
A synapse is the region where one neuron ends and another begins. | Source

Carbon Monoxide as a Neurotransmitter

Carbon monoxide and two other dangerous environmental gases—nitric oxide and hydrogen sulfide—are present in our bodies in very small quantities. These gases appear to play a vital role in a wide range of body processes.

One process involving CO is the transfer of nerve impulses from one neuron, or nerve cell, to another. This transfer is called neurotransmission and is carried out by chemicals. The chemicals are known as neurotransmitters. Carbon monoxide, nitric oxide, and hydrogen sulfide are all neurotransmitters. They behave a little differently from other neurotransmitters, however.

Most neurotransmitters are stored in sacs called vesicles at the end of a neuron. The vesicles release their neurotransmitter molecules when a nerve impulse arrives. The molecules travel across the gap that is present between neurons and bind to receptors on the membrane of a second neuron. Once this union takes place, a new nerve impulse is generated in the second neuron. Some neurotransmitters have the opposite effect and stop a new nerve impulse from being generated.

Carbon monoxide and the other gaseous neurotransmitters aren't stored in vesicles but are rapidly made when they're needed. In addition, they don't bind to receptors on the second neuron but move into the neuron. Like other neurotransmitters they regulate the passage of the nerve impulse. They may actually act as neuromodulators, at least in some parts of the body. Neuromodulators influence the action of neurotransmitters instead of being neurotransmitters themselves.

This screenshot shows stained neurons from the cerebral cortex of the brain. Carbon monoxide is found in brain neurons.
This screenshot shows stained neurons from the cerebral cortex of the brain. Carbon monoxide is found in brain neurons. | Source

Carbon monoxide, nitric oxide, and hydrogen sulfide are sometimes called gasotransmitters instead of neurotransmitters. They seem to have similar functions in the body, but they sometimes work in different ways from each other.

Other Functions of CO

Researchers have discovered some specific functions of carbon monoxide in the body.

  • It relaxes the muscles in the blood vessels, causing the vessels to widen and blood pressure to decrease.
  • In rats, it protects against cardiac ischemia (a restriction in blood flow to the heart).
  • It causes relaxation of the muscles responsible for gut contraction.
  • In lab experiments with animals it reduces inflammation.
  • In the brain, carbon monoxide modulates the release of other neurotransmitters.

Carbon monoxide relaxes the muscles in blood vessels.
Carbon monoxide relaxes the muscles in blood vessels. | Source

Gasotransmitters in the Future

Scientists suspect that gasotransmitters could be used as medications if we understood their behavior better. In 2011 an organization called the European Network on Gasotransmitters, or ENOG, was created. The network holds conferences, meetings, and workshops. Its aim is to discover the functions and methods of action of the different gasotransmitters and to develop their use as medications. The network also wants to discover the differences and similarities in the actions of carbon monoxide, nitric oxide, and hydrogen sulfide.

It's interesting to realize that a potentially deadly gas such as carbon monoxide could have important health benefits. There is so much that we still need to learn about the human body. Understanding more about the action of carbon monoxide and the other gasotransmitters could lead to significant medical advances.


  • Carbon monoxide safety
  • Tinajero-Trejo M, Jesse HE, Poole RK. Gasotransmitters, poisons, and antimicrobials: it’s a gas, gas, gas! F1000Prime Reports. 2013;5:28. doi:10.12703/P5-28.

© 2013 Linda Crampton


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    • AliciaC profile image

      Linda Crampton 2 years ago from British Columbia, Canada

      Thank you, yograj yog. I appreciate your visit.

    • yograj yog profile image

      Yogesh Oza 2 years ago from Ahmedabad, Gujarat, INDIA.

      Very useful information about carbon monoxide. This hub can guide lot of people who use heating devices to protect them from cold. The role of CO to combine with haemoglobin to make it inert is really dangerous. Thanks for providing such a useful guide.

    • AliciaC profile image

      Linda Crampton 4 years ago from British Columbia, Canada

      Yes, carbon monoxide detectors are very important! They do give peace of mind, although we still need to be careful to prevent dangerous situations. Thanks for the comment, shiningirisheyes.

    • shiningirisheyes profile image

      Shining Irish Eyes 4 years ago from Upstate, New York

      Very important subject matter. One of the leading silent killers. I had carbon monoxide detectors installed three years ago and rest easier knowing this.

    • AliciaC profile image

      Linda Crampton 4 years ago from British Columbia, Canada

      Hi, mylindaelliot. Thanks for the visit. It is a difficult situation for people who aren't able to keep warm in their homes. Some people may not know that certain devices can release carbon monoxide. Other people may decide to take the risk. If they know the danger they certainly shouldn't tempt fate!

    • mylindaelliott profile image

      mylindaelliott 4 years ago from Louisiana

      I'm always so surprised that people don't think of this. I know people do what they have to do to keep warm but they should also be vigilant about it.

    • AliciaC profile image

      Linda Crampton 4 years ago from British Columbia, Canada

      Thank you, Ingenira. Unfortunately, CO can be a silent killer, as you say.

    • Ingenira profile image

      Ingenira 4 years ago

      Very comprehensive information on CO.

      CO is a silent killer.

    • AliciaC profile image

      Linda Crampton 4 years ago from British Columbia, Canada

      Hi, Nell. Yes, camping can be a dangerous activity with respect to carbon monoxide poisoning. This is definitely a situation where we should be careful with devices that burn fuels!

    • Nell Rose profile image

      Nell Rose 4 years ago from England

      Scary stuff Alicia, I remember watching the news recently it was talking about people dying in their tents because they had brought in the charcoal barbeques so as not to get wet if it rained! so sad, and something that we all should be made aware of, nell

    • AliciaC profile image

      Linda Crampton 4 years ago from British Columbia, Canada

      Thank you for the visit and the comment, Deb. Carbon monoxide is certainly a surprising chemical!

    • aviannovice profile image

      Deb Hirt 4 years ago from Stillwater, OK

      Thanks for all the info on CO. It is surprising that it is both beneficial and so deadly, too.

    • AliciaC profile image

      Linda Crampton 4 years ago from British Columbia, Canada

      Hi, drbj. Yes, carbon monoxide is a very interesting gas! Thanks for the comment and the vote.

    • drbj profile image

      drbj and sherry 4 years ago from south Florida

      How fascinating, Alicia, to learn that a gas like carbon monoxide which can be deadly may one day provide us with health benefits unknown to us today. Voted up.

    • AliciaC profile image

      Linda Crampton 4 years ago from British Columbia, Canada

      Thank you very much for the comment, the votes and the share, Peggy! It is interesting that very low concentrations of carbon monoxide may have health benefits.

    • AliciaC profile image

      Linda Crampton 4 years ago from British Columbia, Canada

      Hi, Bill. I appreciate the vote and the share, as always! Having working carbon monoxide detectors is so important. Like you, I hear about deaths due to carbon monoxide poisoning every winter. Power failures are certainly dangerous. It's very important that people prepare for them ahead of time.

    • Peggy W profile image

      Peggy Woods 4 years ago from Houston, Texas

      Hi Alicia,

      I had no idea that medical researchers were conducting tests to see if there will eventually be useful purposes for carbon monoxide. Amazing! You have written another useful and interesting hub. Voted that and sharing.

    • bdegiulio profile image

      Bill De Giulio 4 years ago from Massachusetts

      Hi Alicia. This is very important information. Here in New England we hear the sad news every winter of someone who died from CO2 poisoning. You really have to be careful, especially when the power goes out. I have multiple detectors, one on each floor and we religiously change the batteries twice a year.

      Thanks for sharing this info, especially on what this actually does to the body and why it is so dangerous. Voted up, shared, etc...

    • AliciaC profile image

      Linda Crampton 4 years ago from British Columbia, Canada

      Hi, Martie. Thanks for the comment and the vote. I appreciate your visit. It is very sad when carbon monoxide kills people. It's such a dangerous chemical when it's in the environment.

    • MartieCoetser profile image

      Martie Coetser 4 years ago from South Africa

      Alicia, this is an extremely interesting hub and video about carbon monoxide and the fatal result of inhaling it. The fact that some people choose to die from this is beyond my comprehension. Good to know that detectors are available. Voted up and very well presented :)

    • AliciaC profile image

      Linda Crampton 4 years ago from British Columbia, Canada

      Thanks, Bill. Yes, carbon monoxide is nasty - unless it's made inside our body, where it's useful!

    • AliciaC profile image

      Linda Crampton 4 years ago from British Columbia, Canada

      Hi, Vicki! It is scary and also very sad that so many people die each year from carbon monoxide poisoning. Carbon monoxide detectors can be very useful (as long as they are of good quality and have a working battery). Thanks for the visit.

    • billybuc profile image

      Bill Holland 4 years ago from Olympia, WA

      Nasty stuff for sure, Alicia. Very good information here my friend. Thank you!

    • profile image

      Vickiw 4 years ago

      Scary stuff! It ais amazing that more people aren't aware of these dangers. Every year you hear about people who have died after trying to barbecue indoors. Carbon monoxide detectors are quite inexpensive, and save lives.

    • AliciaC profile image

      Linda Crampton 4 years ago from British Columbia, Canada

      Hi, gags3480. Thank you for the comment, the vote and the share!

    • gags3480 profile image

      GAGANPREET SINGH BHATIA 4 years ago from Kanpur, India

      Thanks for the useful info. on this harmful gas.

      Voted up & shared.