Kidney cancers can be cystic, and differentiating between a single benign cyst of the kidney and a kidney cancer can occasionally be a problem. When many cysts are present, as in polycystic renal disease, the distinction is easier. Cysts may also be caused by some parasitic infections.
It will actually collect the oxygen in the ambient air (~21%) and convert it into a concentration of around 85-94%. One of the main reasons you would want a concentrator over a tank and regulator would be when you are using a lot of oxygen for taking ozone saunas or ozonating oils.
Inorganic nitrogen sources The air we breathe is about 78% nitrogen in the form of N 2 gas and about 21% oxygen in the form of O 2 gas. The remaining one percent of the atmosphere is a combination of all the other gases, including carbon dioxide that is the source of carbon used by green plants.