What is the primary component of an exhaled breath?

The primary component of an exhaled breath is carbon dioxide (CO2). When we breathe in (inhale), we take in oxygen (O2) from the air. This oxygen is transported by our blood to cells throughout our body, where it is used for energy production. As a byproduct of energy production, carbon dioxide is produced. This carbon dioxide is then transported back to the lungs, where it is exhaled.