What is the composition of normal air in terms of oxygen and nitrogen?

Normal air is composed of approximately 79% nitrogen and 21% oxygen. This specific composition is critical for a variety of reasons, especially in the context of diving and human respiration. Oxygen is essential for human metabolic processes, while nitrogen acts primarily as an inert filler in the atmosphere.

This balance in the composition of air plays a significant role in maintaining physiological homeostasis. In diving, understanding the normal composition helps divers manage gases they breathe under pressure and recognize the risks associated with nitrogen absorption, such as decompression sickness. As divers descend, the increased partial pressures of these gases can affect their body and dive plans. Therefore, the knowledge of this composition is fundamental in ensuring safe diving practices and making informed decisions regarding gas mixtures when diving to varying depths.

The accurate representation of air composition also aids in dive tables and computer algorithms that help prevent nitrogen narcosis and other related decompression issues. Understanding that air is predominantly nitrogen with a crucial amount of oxygen is not just about environmental knowledge; it's about applying that knowledge for safety.