An oxygen saturation of 70% may cause respiratory failure or cardiac arrest in people at low altitudes. Severe hypoxia or worse requires immediate hospitalization, and depending on the situation, the patient will usually be able to support himself for several hours or even longer. Normal people still experience discomfort after their oxygen saturation level falls below 90%, and their skin may appear dark and even hypoxic. However, for people who have been living at high altitude for a long time, the oxygen saturation level of 70% is usually very likely to be normal, and has no adverse effect on life and the body at all, therefore, the oxygen saturation level should still be judged by people and regions.