What is the percentage of carbon dioxide in expired air?

The percentage of carbon dioxide in expired air is approximately 4%. This concentration is a result of the metabolic processes in the body, where oxygen is used and carbon dioxide is produced as a waste product. When we breathe out, the lungs expel this carbon dioxide, which is a critical component of the respiratory process.

In normal respiration, inhaled air contains around 0.04% carbon dioxide, while the air we exhale is enriched to around 4% due to the body's metabolic activities. This higher level in expired air indicates the role of carbon dioxide as a byproduct of aerobic metabolism, highlighting its importance in maintaining the body's acid-base balance and respiratory drive.

Understanding this concept is crucial for dental nursing, as it relates to patient assessment and management, particularly in procedures that may affect breathing or require monitoring of respiratory function.