Why is exhaled air used as resuscitation?

Exhaled air is used in resuscitation, particularly in techniques like mouth-to-mouth ventilation, because it contains a mixture of oxygen and carbon dioxide, making it effective for delivering oxygen to a person who is not breathing. The exhaled air still contains sufficient oxygen (about 16%) to sustain life temporarily, allowing for the restoration of oxygen levels in the lungs. Additionally, using exhaled air is practical and immediate in emergency situations when other oxygen sources may not be available.