We breathe in a mixture of the first two actually. The air is composed of 78% nitrogen, 21% oxygen, 0.03% carbon dioxide and 0.07% of other gases. Technically, you can also breathe in carbon monoxide if it is present within your environment. However, it has harmful effects. It can<span> enter your bloodstream and mix with hemoglobin </span><span>to form carboxyhemoglobin. The </span>blood<span> cannot carry oxygen anymore, and this causes the body's cells and tissue to die.</span>
