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.
The composition of air is necessary for life on Earth. It is mostly made of nitrogen, around 78 percent by volume. The second most abundant element is oxygen, required for respiratory processes, which makes up about 21 percent of the atmosphere's air.