Carbon Dioxide Poisoning

The Truth About Carbon Dioxide Poisoning

Carbon dioxide naturally exists in air, plus it is produced by combustion and other processes.
Carbon dioxide naturally exists in air, plus it is produced by combustion and other processes. Moussa81 / Getty Images

You are exposed to carbon dioxide every day in the air you breathe and in household products, so you might be concerned about carbon dioxide poisoning. Here's the truth about carbon dioxide poisoning and whether it's something you need to worry about.

Can Carbon Dioxide Poison You?

At ordinary levels, carbon dioxide or CO2 is non-toxic. It is a normal component of air and so safe it is added to beverages to carbonate them. When you use baking soda or baking powder, you are purposely introducing carbon dioxide bubbles into your food to make it rise. Carbon dioxide is as safe a chemical as any you'll ever encounter.

Then Why the Concern Over Carbon Dioxide Poisoning?

First, it's easy to confuse carbon dioxide, CO2, with carbon monoxide, CO. Carbon monoxide is a product of combustion, among other things, and it is extremely toxic. The two chemicals are not the same, but because they both have carbon and oxygen in them and sound similar, some people get confused.

Yet, carbon dioxide poisoning is a real concern. It is possible to suffer anoxia or asphyxiation from breathing carbon dioxide, because exposure to increased levels of carbon dioxide may be related to decreased concentration of oxygen, which you need in order to live.

Another potential concern is dry ice, which is the solid form of carbon dioxide. Dry ice generally is not toxic, but it is extremely cold, so if you touch it you risk getting frostbite. Dry ice sublimates into carbon dioxide gas. The cold carbon dioxide gas is heavier than the surrounding air, so the concentration of carbon dioxide near the floor may be high enough to displace oxygen, potentially posing a danger to pets or small children. Dry ice does not pose a significant hazard when it is used in a well-ventilated area.

Carbon Dioxide Intoxication and Carbon Dioxide Poisoning

As the concentration of carbon dioxide increases, people start to experience carbon dioxide intoxication, which may progress to carbon dioxide poisoning and sometimes death. Elevated blood and tissue levels of carbon dioxide are termed hypercapnia and hypercarbia.

Carbon Dioxide Poisoning Causes

There are several causes of carbon dioxide poisoning and intoxication. It may result from hypoventilation, which in turn may be caused by not breathing often or deeply enough, rebreathing exhaled air (e.g., from a blanket over the head or sleeping in a tent), or breathing in an enclosed space (e.g., a mine, a closet, a shed). Scuba divers are at risk of carbon dioxide intoxication and poisoning, usually from poor air filtration, not breathing at the normal rate, or simply from having a harder time breathing. Breathing the air near volcanoes or their vents may cause hypercapnia. Sometimes carbon dioxide levels become imbalanced when a person is unconscious. Carbon dioxide poisoning can occur in space craft and submarines when scrubbers aren't functioning properly.

Carbon Dioxide Poisoning Treatment

Treatment of carbon dioxide intoxication or carbon dioxide poisoning involves getting carbon dioxide levels back to normal in the patient's bloodstream and tissues. A person suffering from mild carbon dioxide intoxication typically can recover simply by breathing normal air. However, it is important to communicate a suspicion of carbon dioxide intoxication in case the symptoms worsen so that proper medical treatment may be administered. If multiple or serious symptoms are seen, call for emergency medical help. The best treatment is prevention and education so that conditions of high CO2 levels are avoided and so you know what to watch for if you suspect the levels may be too high.

Symptoms of Carbon Dioxide Intoxication and Poisoning

  • Deeper breathing
  • Twitching of muscles
  • Increased blood pressure
  • Headache
  • Increased pulse rate
  • Loss of judgment
  • Labored breathing
  • Unconsciousness (occurs in under a minute when CO2 concentration rises about 10%)
  • Death


  • EIGA (European Industrial Gases Association), "Carbon Dioxide Physiological Hazards - Not Just an Asphyxiant", retrieved 01/09/2012.

Key Points

  • Carbon dioxide poisoning results in a condition called hypercapnia or hypercarbia.
  • Carbon dioxide intoxication and poisoning can elevate pulse rate and blood pressure, produce a headache, and result in poor judgement. It can result in unconsciousness and death.
  • There are multiple causes of carbon dioxide poisoning. Lack of air circulation, in particular, can be dangerous because breathing removes oxygen from the air and adds to its carbon dioxide content.
  • While carbon dioxide can be toxic, it is a normal component of air. The body actually uses carbon dioxide to maintain proper pH levels and to synthesize fatty acids.
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Your Citation
Helmenstine, Anne Marie, Ph.D. "Carbon Dioxide Poisoning." ThoughtCo, Aug. 27, 2020, Helmenstine, Anne Marie, Ph.D. (2020, August 27). Carbon Dioxide Poisoning. Retrieved from Helmenstine, Anne Marie, Ph.D. "Carbon Dioxide Poisoning." ThoughtCo. (accessed June 12, 2021).