Every breath a person takes draws from a gas mixture that has barely shifted in recorded history: roughly 78 percent nitrogen ...

Earth was mostly devoid of oxygen for much of its 4.5 billion year lifetime. That is, until certain processes started to ...

Today, oxygen takes up a hefty portion of Earth’s atmosphere: Life-sustaining O2 molecules make up 21 percent of the air we breathe. However, very early in Earth’s history, O2 was a rare — if not ...

Earth's atmosphere wasn't always full of life-giving oxygen — it was once a choking mixture of carbon dioxide and other gases, more like the atmosphere of Mars or Venus. It's widely believed that the ...

Oxygen photosynthesis has to be the greatest giver of life on Earth, and researchers have cracked yet another part of its complex and efficient chemistry. The more we know about it, the better we may ...

Oxygen therapy helps people with emphysema breathe more easily. In the later stages of the illness, oxygen may also extend someone’s life. Emphysema is a type of chronic obstructive pulmonary disease ...