MadSci Network: Environment

Re: How long can you live without air

Date: Tue Apr 1 16:34:18 2003
Posted By: June M. Wingert , RM(NRM),Associate Scientist
Area of science: Environment
ID: 1048678263.En

Greetings Aviva:

At first I thought that this was a pretty straightforward question to answer, but, the more I researched it , the more I found it to be complex. So,,, here is the multi-answer to your question. How long can you live without air? MINUTES!

Clearly the importance of available oxygen to every cell of the body is a matter of health or sickness, weariness or vitality, a weak immune system or a strong one, and even life or death. In fact, after about 6 minutes the brain without oxygen begins to die. It is an essential nutrient. The brain becomes dead.

From this Wired article:
If someone is brain dead, the person is dead, period. This fact can be hard to accept, particularly when a patient might look very much alive to family members. Brain dead people often still have a heartbeat, and their chests may rise and fall with the help of a ventilator, sometimes giving hope to grieving families that the person may suddenly wake up. The simple fact remains, a brain dead person is a dead person.

All states have since recognized that doctors can use "brain death" as the sole criterion for determining that a patient has died. Doctors must perform various tests to verify brain death. If the tests show brain activity, the patient may be in a coma or vegetative state. A brain dead person doesn't show brain activity.
Point your browser to this URL for a list of the various tests doctors use to determine brain death.

There is also phenomenon called Cold Water Drowning

This is a situation where the 6 minutes does not apply. The following information was taken from the Geophysical Institute, University of Alaska Fairbanks, in cooperation with the UAF research community. T. Neil Davis is a seismologist at the institute.

"Spring starts the season when children fall through the ice; later in the year many adults drown while swimming or boating in Alaskan waters. Drowning is the second-leading cause of accidental death in Alaska Cold is usually an enemy to life, but in some instances it is a friend. In recent years scientists have learned that people can be submerged in cold water for long periods without brain damage or other lasting harm. In March 1975, an 18-year-old man was submerged in a freezing Michigan pond for 38 minutes. Declared dead, he was on the way to the morgue when he gasped and caused a diversion of the transporting vehicle to the nearest hospital. Two weeks later he returned to college and continued to be an A student. But two hours of resuscitation were required to bring him around.
The lesson is very clear. Rescuers should not give up when someone appears to have drowned in cold water. Resuscitation should be continued at least until the person's body comes up to normal temperature--hours may be required.
However, it is absolutely necessary for resuscitation to be started within a very few minutes after the victim is taken from the water. The reason is that a person plunging into cold water undergoes the "diving response." As soon as the cold water strikes the person's face, the diving response is triggered. It reduces the blood supply to the skin and most muscles and saves it for the heart and brain. A person comes out of the diving response when taken from the cold water, so speedy action is needed then. The younger the person, the better the chances for survival. Newborn mammals are remarkably resistant to drowning, but as they grow older, their effectiveness in using the diving response decreases. Doctors have found that relatives tend to give up too soon when a family member is thought to have drowned. The doctors explain this giving up as a result of guilt feelings about the apparent drowning. The moral is--don't give up--especially if the water is cold, as it almost always is in Alaska."

So, the answer to your question is: under the usual circumstances the human body can not live without air for approximately 6 minutes.

Hope this sufficiently answers your question.
Thanks for taking the time to send in a question to Mad Sci.

June Wingert
Associate Scietist
A Biotechnology Firm

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