Why you smell while are exhaling?

When you inhale, the air goes through your nostrils, bringing oxygen to your lungs where it travels to your blood stream. As the diaphragm pushes to release air out of the lungs, it carries the carbon dioxide produced by the cells as waste to be expelled from the body. During this process, the air from the lungs can carry a mixture of carbon dioxide and volatile organic compounds (VOCs) that were produced by the bacteria in the mouth, nose, throat and lungs. These VOCs can cause the exhaled air to smell.

Additionally, the smell of exhaled air can also be affected by the foods you eat, your dental health, and whether you smoke or not.