The air a person normally breathes contains approximately 21 percent oxygen. The concentration of oxygen delivered to a victim through rescue breathing is 16 percent.  A condition known as hypoxia (insufficient oxygen to the body) can occur if a person goes without adequate oxygen for an extended period.

Signs and symptoms of hypoxia include:

•  Increased breathing and heart rate
•  Changes in level of consciousness
•  Restlessness
•  Cyanosis (bluish color on lips and nailbeds)
•  Chest pain