The element that makes up the most percentage of air is _____?

Nitrogen constitutes the largest percentage of the earth's atmosphere, making up about 78% of the air by volume. This inert gas plays a crucial role in maintaining the balance of the atmosphere and is vital for various biological processes, although it is not directly utilized by humans for respiration.

The dominance of nitrogen in the atmosphere is significant in the context of HVAC systems as well. Understanding the composition of air is essential for managing indoor air quality, optimizing combustion processes, and ensuring effective ventilation strategies.

In contrast, while oxygen is necessary for human life, it comprises about 21% of the atmosphere. Carbon dioxide is present in trace amounts (approximately 0.04%) and is a product of combustion, while argon is a noble gas that constitutes about 0.93% of the atmosphere. This context illustrates the importance of nitrogen beyond its mere presence in air composition, particularly in systems related to heating, ventilation, and air conditioning.