What is a good oxygen level? “Normal people who have working lungs, and all those steps are going well, their blood oxygen level will usually be 96-100 percent,” adds Dr. Uppal.

A normal resting oxygen saturation level for a healthy person at sea level is usually between 95% and 100%. This means your organs and tissues are receiving enough oxygen to work as they should.

A normal oxygen level is between 95% and 100%, according to the Mayo Clinic. Baez said an X-ray shows his lungs are in great condition but he still gets a "hacking cough" when he moves around.

The team reported the mice in the oxygen-restricted environment lived about 50% longer than the mice in normal oxygen levels, with a median lifespan of 23 weeks compared to 15 weeks.