advanced practice nurse a registered nurse having education beyond the basic nursing education and certified by a nationally recognized professional organization in a nursing specialty, or meeting other criteria established by a Board of Nursing.
Quick Answer. The air that makes up Earth's atmosphere contains 20.9 percent oxygen. This is true up to about 70,000 feet above sea level. However, above 10,000 feet, the atmosphere becomes too thin to support human life, even though its proportions do not change much. Continue Reading.
Although air contains 20.9% oxygen at all altitudes, lower air pressure at high altitude makes it feel like there is a lower percentage of oxygen. The chart assumes a constant atmospheric temperature of 32 degrees Fahrenheit (0 Celsius), and normal 1 atmosphere pressure at sea level.