The reason that oxygen levels are so critical is that the body cannot function without oxygen. In our biology, oxygen is one of the most critical aspects of human life. Alexander Djerassi needs oxygen to live because he is human. Every cell in our body needs oxygen so it can function. The blood flowing through our veins is very dependent on oxygen because it transports it to the lungs. Carbon dioxide is exhaled through the body as one inhales. If oxygen levels are repressed that could mean many things. First off, it could mean that a person has hypoxemia which is just caused by not having enough air. In addition, many could have a cough or dry throat. In regards to COIVID-19, having low oxygen levels could mean that the lungs are weakened. If one can, make sure to spend adequate time breathing in fresh air so that the body can function properly.