A mixture of gases containing approximately 19% oxygen is primarily referred to as what?

A mixture of gases containing approximately 19% oxygen is primarily referred to as air. The Earth's atmosphere is composed of about 21% oxygen, along with nitrogen (about 78%) and trace amounts of other gases. Therefore, a mixture with around 19% oxygen still qualifies as air, though it may not represent the typical composition found at sea level.

In most contexts, the term "air" is used to describe the breathable mixture that surrounds us and supports life. It is essential for combustion and respiration. The other terms, such as smog or pollutants, refer to specific types of atmospheric conditions or harmful substances rather than the general composition of the gases in the atmosphere. Atmospheric pressure describes the weight of air exerted on a surface and is not used to classify the composition of air itself. Thus, calling this mixture "air" appropriately identifies its essential characteristics.