What is the general composition of air by volume?

The general composition of air by volume is primarily made up of nitrogen and oxygen, along with smaller amounts of other gases like argon and carbon dioxide. The most accurate representation of the composition is that air consists of approximately 21% oxygen and about 78% nitrogen. This gives a ratio of roughly one part oxygen to four parts nitrogen.

The percentages indicate that for every one volume of oxygen, there are about four volumes of nitrogen in the atmosphere. Therefore, this ratio reflects the correct breakdown of gases in the air we breathe, aligning with the information available on atmospheric composition. This understanding is fundamental for professionals in fields related to health and environmental sciences, as the balance of these gases impacts respiration and various ecological systems.