Carbon Monoxide in Cigarette Smoke

How does carbon monoxide hurt smokers?

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What is Carbon Monoxide?

Carbon monoxide (CO) is a poisonous, colorless and odorless gas that is produced as a result of incomplete burning of carbon-containing fuels. It is present in indoor and outdoor air in varying amounts from things like vehicle exhaust, gas stoves, wood-burning stoves and furnaces. Cigarette smoke can contain high levels of carbon monoxide. 

Carbon Monoxide in the Body

When carbon monoxide is breathed into the lungs, it binds with hemoglobin in red blood cells to make carboxyhemoglobin (COHb) which is then transported into the bloodstream.

Once this happens, oxygen cannot bind with receptors on the same cell. And because CO is much faster at binding with hemoglobin than oxygen (about 200 times faster), when CO is present in the lungs, it wins the spot on red blood cells.

Carbon monoxide is quick to connect with red blood cells, but is slow to exit the body, taking as much as a day to be exhaled through the lungs.

An abundance of carbon monoxide in the bloodstream starves the body of oxygen and in the worst cases, can cause death.

Carbon Monoxide in a Smoker's Body

The normal level of COHb in the bloodstream from environmental exposure to carbon monoxide is less than one percent.

For smokers, factors like brand, how many cigarettes are smoked and the amount of time between cigarettes can cause COHb saturation in the blood to be much higher. A pack a day smoker can have a 3 to 6 percent COHb level in the blood,  two packs a day, 6 to 10 percent, and three packs a day, as much as 20 percent.

The health effects of CO saturation in the blood above one percent become noticeable as well:

From 1% to 5%, heart rate goes up.

From 2% to 15%, exercise tolerance goes down.

From 15% to 20%, headache and visual distortions can occur.

Lack of oxygen in cells also forces the heart to work harder to distribute oxygen around the body, making CO a major contributor to heart disease, including heart attacks and atherosclerosis.

Secondhand smoke may also contain high levels of CO, so non-smokers who breathe in ETS will have increased levels of CO in their blood also.

Can Smoking Cause Carbon Monoxide Poisoning? 

It is possible to suffer CO poisoning from cigarette smoking if a large number of cigarettes are smoked in quick succession in an enclosed space. For most smokers though, symptoms of too much CO, like a racing heart, headaches and nausea will cause them to slow down on the smokes enough to not need medical help.

In one documented extreme case, a woman made a trip to the emergency room at her local hospital because she felt dizzy and had a headache. Blood work revealed an elevated level of carbon monoxide in her blood.  Her home was checked for a carbon monoxide leak and none was found.  

A week later she returned to the hospital with the same symptoms. This time, the carbon monoxide in her blood was nearly 25 percent. It's no wonder she felt so bad. She was a heavy smoker of over two packs a day and had smoked numerous cigarettes in a short period of time.

The doctor treated her with oxygen and she recovered, but the only way to solve her problem for the long tern was to quit smoking.

Symptoms of Carbon monoxide poisoning:

Breathing low levels of CO can cause:

  • fatigue
  • increased chest pain in people with chronic heart disease

In otherwise healthy people, inhaling higher levels of carbon monoxide may cause flu-like symptoms (with no fever) such as:

  • headaches
  • dizziness
  • weakness
  • sleepiness
  • nausea
  • vomiting
  • confusion
  • disorientation

At very high levels, exposure to carbon monoxide will cause loss of consciousness and death, so it is important to seek medical attention if you experience any of the symptoms above.

More on the Chemicals in Cigarette Smoke:

Secondhand smoke is a toxic cocktail of over 7,000 chemical compounds, 250 of which are known to be poisonous and upwards of 70 that have been identified as carcinogens.


American Journal of the Sciences. Recurrent Carbon Monoxide Poisoning from Cigarette Smoking. Volume 340, Issue 5, November 2010, Pages 427–428.

Agency for Toxic Substances and Disease Registry. Public Health Statement for Carbon Monoxide. Updated January, 2015.

New York State Dept of Health Tobacco Control Program. Cigarette Smoking, Carbon Monoxide and Your Health. Accessed November, 2015.

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