What gas in the air is not involved in breathing?

Nitrogen makes up most of our atmosphere. About 78% air. But he is not involved in our breathing. In fact, we do not use it, but it is important. We cannot breathe only oxygen, carbon dioxide and other gases without nitrogen. Oxygen, for example, is very toxic and poisonous in its pure form. It starts the process of destruction of red blood cells. Carbon dioxide takes up only 0.03% of the air. With more concentration, we begin to feel it. Nitrogen plays the role of an “adjuvant”, as in a drug it can be alcohol or another solution that dilutes the active ingredient.