Oxygen Deficient Chart

Oxygen, a colorless odorless molecule, is the eighth element of the periodic table and third most abundant element by mass in the universe after hydrogen and helium. In addition to being the essential ingredient for cellular respiration (or breathing), millions of tonnes of O2 is extracted annually for industrial purposes such as water treatment, medical, aerospace, metal-working, and chemical industries.

While oxygen is essential for all living organisms on earth as well as a vital component for industrial and manufacturing purposes, too much or too little oxygen can have serious consequences from serious injury and accidents to death. Please familiarise yourself with the effects of a oxygen deficient atmosphere.

heart-icon.png 23-19.5%

Safe Oxygen Levels

19.5% is the minimum acceptable oxygen level. Levels over 23.5% pose an increased risk for fire or explosions.

heart-icon.png 15-19%

First signs of Hypoxia

Decreased ability to work strenuously. May impair coordination and may induce early symptoms in persons with coronary, pulmonary or circulatory problems.

pulse-icon.png 12-14%

Increased Pulse

Respiration increases in exertion, pulse raised, impaired coordination, perception and judgement

brain-icon.png 10-12%

Abnormal fatigue

Respiration further increases in rate and depth, poor judgement and blueness of lips.

ambulance-icon.png 8-10%


Mental failure, fainting, unconsciousness, ashen face, blueness of lips, nausea and vomiting.

death-icon.png <10%


Inability to move, loss of consciousness. Coma in 40 seconds, convulsions, respiration ceases and death.

Note: Exposure to atmospheres containing 12% or less oxygen will bring about unconsciousness without warning and so quickly that the individual cannot help or protect themselves. ​ When personnel are subjected to, and around, oxygen-deficient atmospheres, there are certain considerations which are as follows: 

1) Analyze the atmosphere to determine if there is enrichment or deficiencies of oxygen, continue to monitor during work process.
2) Train the worker on what to expect and how to handle it.
3) Blank any incoming lines to a confined area and ventilate the area.
4) When it is necessary to work in any oxygen-deficient atmosphere, provide self-contained breathing apparatus for all workers.