NAFA Certified Air Filter Specialist (CAFS) Practice Exam

The primary component of the air we breathe is nitrogen, which makes up about 78% of Earth's atmosphere. This gas is essential for various biological and chemical processes but does not participate significantly in the respiration of aerobic organisms. While oxygen is crucial for life and constitutes about 21% of the atmosphere, nitrogen is more abundant and plays a supportive role in maintaining atmospheric stability. The presence of carbon dioxide and argon in the atmosphere is minimal compared to nitrogen. Carbon dioxide is vital in the context of photosynthesis and climate interactions, and argon is a noble gas that does not react with other elements. However, in terms of sheer volume in the atmosphere, nitrogen is unmistakably the primary component.