Take a deep breath. Now exhale. Congratulations! You’ve just done something completely ordinary, yet so mysterious that scientists still don’t know everything about it.
How oxygen and carbon dioxide enter and leave the bloodstream is well known, but scientists are just beginning to understand what happens to respiratory tissues as they expand and contract with every breath. The answers they find could help identify better ways to diagnose and treat lung diseases, including the deadly illnesses associated with vaping, cigarettes, and/or air pollution exposure.
news.ucr.edu/articles/2019/...
The research paper is here:
Daughter’s lung biopsy
Aspergillosis and Hyperinflated lungs. 
Lung Sensation Question (General)
Hurts breathing in on left side/lung...
lung volume reduction operation
