Why is there more co2 in the air that you breathe out than in the air that you inhale?

CO2 is produced during respiration by mitochondria.

To know why there is more CO2 in the air that you breathe out than the CO2 which you inhale, we have to know that the carbon which we breathe out as carbon dioxide comes from the waste products (the carbon in the food we eat) like the carbohydrates, fat, and protein which converted in the body by biochemical pathways to glucose. the end products of oxidation of glucose are water and carbon dioxide. This carbon dioxide which dissolved in the human blood is carried to the air in the lung by circulation before it exhales.