Environmental, Health and Safety Services

What are some effects of oxygen deficient atmospheres?

Normal air contains approximately 20.8% oxygen by volume.  The minimum safe level for confined space entry is 19.5%.  As the oxygen level decreases, the following signs and symptoms may be experienced:

  • At 15%, impaired muscle coordination, increase heart rate, rapid fatigue, and intermittant respirations.
  • At 12%, judgment may become impaired and respirations continue to increase due to the lack of oxygen.
  • At 10%, lips may begin to turn blue, respirations increase, nausea, and inability to perform simple tasks.
  • At 8%, fainting and vomiting can occur.
  • At 6%, death can occur in about 8 minutes.
  • At 4%, likely coma in about 40 seconds, with possible recovery within 4 minutes.

Continuous air monitoring and ventilation is the best means of prevention.