The fraction of oxygen saturated haemoglobin relative to total haemoglobin is called SpO2. It is necessary to estimate an individual’s fitness level, which is usually given in percentages. SpO2 (oxygen saturation) is affected by a number of parameters, including oxygen availability, pulmonary gas exchange, haemoglobin content in red blood cells, and haemoglobin affinity for oxygen. A healthy person’s normal oxygen level is between 95 and 100 percent. Normal saturation levels suggest that the body is getting enough oxygen and that the internal organs are functioning properly. A very low blood oxygen level for a short period of time does not pose a major threat. However, if it continues, it puts strain on the heart and brain, as well as causing organ damage. The PPG signal obtained from a fingertip pulse oximeter is commonly used to measure SpO2 (oxygen saturation).  Chronic diseases such as asthma, heart disease, and chronic obstructive pulmonary disease (COPD) cause low blood oxygen levels.