Is it harmful to breathe 100 percent oxygen?

Oxygen is a necessary component of the air we breathe; but in its pure form, it can be hazardous to one's health. Marshall Brain explains how breathing pure oxygen harms the human body in this episode.

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Episode Transcript

Speaker 1 (00:00):
Welcome to brain Stuff from house stuff works dot com,
where smart happens him Marcial Brain with today's question, is
it harmful to breathe on oxygen? You think, since we

(00:20):
need oxygen to live, that it would be okay to
breathe on oxygen, And it is okay for an hour maybe,
But if you breathe on oxygen for more than an hour,
it starts to cause big problems. So the short answer
is pure oxygen is generally bad and sometimes toxic. To

(00:42):
understand why, you need to go a little deeper. Your
lungs are basically a long series of tubes that branch
out from your nose and mouth and end in little,
thin walled air sex called a viola. I think of
soap bubbles on the end of a straw and you'll
understand a viola. Surrounding each aviolas are small, thin walled

(01:06):
blood vessels called pulmonary capillaries. Between the capillaries and the
aviolas is a thin wall about point five microns thick,
through which various gases in our case, oxygen, carbon dioxide,
and nitrogen can pass. When you inhale, the aviol i
fill with this air because the oxygen concentration is high

(01:29):
in the aviola and low in the blood entering the
pulmonary capillaries. Oxygen diffuses from the air into the blood. Likewise,
because the concentration of carbon dioxide is higher in the
blood that's entering the capillaries than it is in the
aviolar air, carbon dioxide passes from the blood to the avioli.

(01:51):
The nitrogen concentration in the blood and in the aviolar
air is about the same. The gases exchange across the
aviol or wall, and the air inside the avoli becomes
depleted of oxygen and rich in carbon dioxide. When you exhale,
you breathe out this carbon dioxide enriched oxygen pour air.

(02:13):
Now what would happen if you breathe on oxygen? In
guinea pigs exposed one oxygen at normal air pressure for
forty eight hours, fluid accumulates in their lungs and epithelial
cells lining the avola. In addition, the pulmonary capillaries get damaged.

(02:33):
A highly reactive form of oxygen called the oxygen free radical,
which destroys proteins and membranes and the epithelial cells, probably
causes this damage in humans, breathing one oxygen at normal pressure,
the same kind of thing happens. First, fluid accumulates in

(02:53):
the lungs that causes the gas flow across the aviol
to slow down, meaning that the person has to breathe
more to get enough oxygen. Then mucus starts to plug
up local areas of collapsed a viola. The oxygen trapped
inside these plugged a viola gets absorbed into the blood

(03:15):
and no gas is left to keep the plugged avio
l a inflated, so they collapse. Mucus plugs are normal,
but they're cleared by coughing, but coughing doesn't work when
the avioli have collapsed. If avoli become plugged when breathing
normal air, the nitrogen trapped inside the avial i keeps

(03:35):
them inflated and prevents this clogging from happening. The astronauts
in the Gemini and Apollo programs breathed oxygen for up
to two weeks with no problems, So what was going
on there? That's because the pressure inside the capsule was reduced.
Today astronauts who are using spacesuits are breathing pure oxygen

(03:58):
as well, but the pressure inside their suits is also
reduced to improve mobility. Do you have any ideas or
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(04:20):
dot com home page