How is oxygen saturation in the body affected when altitude increases?
At sea level, oxygen saturation in the blood is approximately 95%, which does not appreciably decrease up to pressure altitudes of 10,000 ft. at which point it decreases to about 90%. Above 10,000 ft, the saturation drops more rapidly and human faculties begin to be impaired. Above 14,000 ft, physiological symptoms begin to appear. For more detailed information, see The Pilot’s Atmosphere and Hypoxia on MHOxygen.com.