As a respiratory therapist with extensive experience in respiratory care, I can provide insight into the effects of breathing pure oxygen on the human body. Breathing pure oxygen, especially at high concentrations for an extended period, can indeed be harmful. The human body is adapted to breathe air that contains approximately 21 percent oxygen. When we inhale pure oxygen, it can lead to a condition known as oxygen toxicity. Oxygen toxicity can cause a variety of symptoms, including shortness of breath, coughing, chest pain, and even seizures or death in severe cases. The toxicity of oxygen is due to the fact that oxygen can act as a free radical, which can damage cells and tissues in the body. This is particularly a concern for the lungs, as they are the primary site of contact with the high concentration of oxygen. Prolonged exposure to high levels of oxygen can lead to a buildup of fluid in the lungs, known as pulmonary edema, which can impair lung function. Moreover, the body's tissues are not designed to handle the increased oxidative stress that comes with breathing pure oxygen. This can lead to cellular damage and has the potential to cause long-term health issues. In medical settings, pure oxygen is sometimes administered for short periods to patients who are experiencing hypoxia (low oxygen levels in the body). However, it is always done under the supervision of medical professionals who monitor the patient's condition closely to prevent the onset of oxygen toxicity. In summary, while oxygen is essential for life, breathing pure oxygen can be detrimental to one's health. It is important to maintain the natural balance of gases in the atmosphere that we breathe. read more >>

We breathe air that is 21 percent oxygen, and we require oxygen to live. So you might think that breathing 100 percent oxygen would be good for us -- but actually it can be harmful. So, the short answer is, pure oxygen is generally bad, and sometimes toxic. ... When you inhale, the alveoli fill with this air.read more >>