Researchers discover how too much oxygen damages cells and tissues

When it comes to oxygen, you can have too much of a good thing. Breathing air that contains higher levels of oxygen than the usual 21 percent found in Earth's atmosphere can cause organ damage, seizures, and even death in people and animals, particularly if it's in excess of the body's oxygen needs. Until now, however, scientists have mostly speculated about the mechanisms behind this phenomenon, known as oxygen toxicity, or hyperoxia.