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Can Oxygen Be Toxic?

Can oxygen sometimes be toxic? Find out on today's Moment of Science.

picture of woman with oxygen mask on

Photo: Kaeru (Flickr)

Could oxygen kill someone?

In order for us to live we must have oxygen, so how can it be bad for us? Today we explain how oxygen can be toxic.

Toxic? Really?

Unbeknown to most people, too much oxygen can be toxic. After several days of breathing nothing but pure oxygen, you’d begin to experience nausea, dizziness, muscle twitches, and convulsions. You might even die.

Ironically, too much oxygen actually inhibits ventilation and ends up slowing down the delivery of oxygen to your body’s tissues. Another problem is that certain tissues, like the lining of the lungs and the walls of the arteries, are very sensitive to oxygen. The cornea is also very sensitive to oxygen; you may have heard of people who have gone blind because, as newborns, the oxygen levels in their incubators were too high.

Oxygen Molecules

Scientists aren’t really sure why oxygen affects the body this way. Some think it has to do with a special form of the oxygen molecule which bonds with the proteins and membranes in the lining of the lungs, and ends up destroying them. In other words, with too much oxygen around, your insides begin to oxidize.

  • Gonzalo Fernandez

    And that same oxygen wich “keeps us alive” is the same one wich deteriorate our system leading to cell degeneration (getting old, wrinkled and weak) and then to death. Ironies of life :-/

  • microl chen

    why are we still alive then??

  • Nick Thompson

    Because it isnt a very strong toxin

  • Nick Thompson


  • Pat RIOT

    So what do you think of the products where you can inhale pretty much 95% pure oxygen like athletes do during sideline breaks?

  • Tania pearson

    Because its part of a compound with hydrogen and nitrogen for us to breathe.


    Oxygen makes us living but destroys us inside basically.

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