Normal Oxygen Level in Humans

According to the Medical News Today website, the normal level of arterial oxygen in human beings is between 12 and 14 kilopascals (kPa). Anyone with a level below 8kPa is considered to be critically ill.

Oxygen Deficiency

Oxygen deficiency typically leads to dizziness, fatigue and memory loss. Other symptoms include respiration, circulation and digestion problems, lowered resistance to bacterial and viral infections, muscle aches and, ultimately, death.

Causes

Medical conditions such as emphysema and chronic bronchitis -- known generically as chronic obstructive pulmonary disease -- can cause the oxygen level in the blood to fall below that required for the body to function normally.

Treatment

Traditionally, oxygen deficiency has been treated by artificial ventilation with pure oxygen. Pure oxygen, however, acts as a poison that can cause damage to the lungs through swelling.

Lowest Level

The lowest level of arterial oxygen in a living human being, 2.55kPa, was recorded in a climber near the summit of Mount Everest at a height of 29,000 feet. The expedition was led by doctors from University College London.

References

• Applied Ozone Systems: Oxygen Deficiency Disease
• Medical News Today: Mountaineers Measure Lowest Human Blood Oxygen Levels On Record
• Guardian.co.uk: Humans can survive much lower blood oxygen levels than thought
• PCCA: Home Oxygen Therapy