Normal CO2 Levels in Blood

Written by Torque Earnest,

Carbon dioxide allowed in drugs for humans is 130 times higher than the current atmospheric content of carbon dioxide gas. So what gives? The normal CO2 levels in blood is in the range of 30 – 40mm of Hg. High or low levels of carbon dioxide leads to hypercapnia or hypocapnia respectively. CO2 imageThis article gives you information on this subject.

CO2 is the chemical formula of carbon dioxide, one of the gaseous variants of the element Carbon, which is also present in our body and is an essential constituent. Though it is more synonymous with the harmful Greenhouse gases which are responsible for the Ozone depletion, it is very much an important constituent of our body. If the normal CO2 levels in blood drops, we may suffer from cerebral vasoconstriction plus many other issues.

The permissible levels of CO2 in blood is only 5% in case of drugs. The basic reason behind raising the normal CO2 levels in body is because of the function of carbon dioxide. It helps balance the oxygen levels in certain medical conditions like apnea. It also acts as a stimulant for more oxygen intake. Apnea or sleep apnea is a disorder in which the oxygen levels decrease in the body. We will now see the symptoms and repercussions of varying normal carbon dioxide levels in blood in the following paragraphs.

High carbon dioxide levels in blood is usually noticed in smokers as they inhale carbon monoxide which again is very harmful. Readings of increased levels of CO2 in blood is anything above 45 mm of Hg and this condition of the body is called hypercapnia. Hypercapnia is caused by various reasons, one of which is hypoventilation. As the name suggests, hypo-ventillation is related to the exchange of gases in our body with the atmosphere.

An interesting fact here is that the percentage of carbon dioxide allowed in the administration of drugs for humans is 5%, as mentioned earlier, but if compared with the normal atmospheric content of carbon dioxide gas, it is 130 times higher!

Symptoms of Hypercapnia


High blood pressure

Flushed skin


Slack neural activity

Muscle twitching

Extra systoles

It is not that the body segregates carbon dioxide and keeps it in. What happens exactly in this condition is that the body is not able to exhale the inhaled air completely.

Low carbon dioxide levels in blood can cause symptoms that might go unnoticed because, the symptoms in early stages of hypocapnia are similar to those when one is fatigued or sleep deprived. The following list gives you the symptoms. It is important to note that these are also signs of carbon dioxide poisoning.

Symptoms of Hypocapnia

Optical malfunction


Muscle cramps

Visual blackouts

Panic attacks


Hypocapnia is observed in cases of hyperventilation. This term is the opposite of hypoventillation, as explained above. This condition triggers increase in the alkaline levels in the body. The reason behind this reaction is that the pH levels get increased because one of the functions of CO2 is to balance the acid levels in the body.

Hope this article helps you in keeping a tab on the symptoms mentioned here and take better care of yourself.


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Comments (5)

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    Correct exactly, as in the normal state the respiratory response is to the CO2 in the blood rising not the O2 decreasing, and in the chronic state the reverse is the case. increasing ventilation decreases CO2. I assume he came across the acute management and thought it was the norm. The expiratory CO2 in the norm is usually balanced around 40,000ppm which is what I think he meant as being non toxic, and the stimulatory mix is at 50,000ppm, and normal administered O2 is pure but limited to maintaining a mix a few percent above normal usually by limiting flow rate. If the O2 is too high in chronic lung disease especially, ventilation decreases as O2 remains up, and CO2 is then retained, possibly fatally.

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    Ian Forrester


    FauxScienceSlayer does not understand the use of medical oxygen supplemented with 5% CO2. This is not normal oxygen which is given to patients but is a special gas mixture only used in hospitals under strict supervision. It is only given to patients who have been known to have stopped breathing. The included CO2 encourages the breathing reflex to be re-established in these patient.

    This mixture is not the one used by people who need supplemental oxygen in their air supply.

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    Diminished levels of blood CO2 and hyperventilation are virtually an everyday presentation to a physician. Simply the auscultation of the chest by stethoscope and asking the patient to breath deeply for 20 or so breaths causes the symptoms of light-headedness. It is a regular occurrence for patients to be carried into the surgery by relatives, the patient in hysterics and assuming they are dying. This is called hysterical hyperventilation. The first symptoms are in the longest nerves and mainly tingling in the fingers, though eventually tetanic like cramps of the hands can result as muscle fibres join in. The cause is the reduced buffering by reduction of bicarbonate in the blood. The brain with 10 to the 15 neurones doesn’t tingle but puts out emergency signals that induce adrenaline output which in a feed back fashion cause reflex hyperventilation. The patient feels a sense of impending doom. As noted above humans can work happily in environments up to 30,000ppm CO2 without hypercapnia. We can also use our kidneys to excrete extra bicarbonate. It often surprises people to learn that haemoglobin transfers oxygen to the cells, but we need the dissolved CO2 to slowly wend its way back to the lungs for ventilation to remove it to stay well. Also in chronic lung disease, the body response to O2 governs ventilation and given excess O2 the CO2 can rise to fatal levels hence the comment above.

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    What the hell kind of TOXIN is this ? ? ?

    Medical Oxygen MUST contain 5% Carbon Dioxide to allow you to balance your blood pH or DIE from OXYGEN POISONING. Humans, being Carbon Life Forms, inhale 400 PPM of CO2 and exhale 40,000 PPM of CO2 until we die. At that point bacteria deconstruct our organic compounds and release CO2 from decomposition.

    We have been systematically LIED to about EVERYTHING.

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