Oxygen is critical to life. It is the transport carrier of haemoglobin, through which oxygen is supplied to our bodies cells through the bloodstream. In healthy people, oxygen saturation should be between 94-99%. When it falls below this level, it can be dangerous. , Previously, blood oxygenation levels could only be understood by taking blood. Now, through pulse oximetry, it is possible to measure oxygen saturation levels with an external meter that analyses the blood color. Measuring oxygen saturation can alert people to the potential for hypoxia (or oxygen starvation) and is of increasing assistance in sports as an indicator of good health.