8 Interesting Facts About Lungs October 17, 2016 by admin In Social Clips. 5. Oxygen only plays a small part in breathing. The air we breathe contains 21 percent oxygen, but our bodies only use 5 percent — the rest is exhaled. Study reveals the risk factors identified for bronchiectasis in COPD patients. Read more here. Print This Page Pages: 1 2 3 4 5 6 7 8