It follows that lung damage (which can be, ironically, caused by breathing more than 50% oxygen) might lead to lower oxygen levels.<p>"The brain requires a constant supply of glucose and oxygen. However, if you have a chronic lung disease such as emphysema, pulmonary fibrosis or COPD, having enough blood oxygen can be challenging.... The brain uses about 25 percent of your oxygen intake, so avoiding low oxygen and brain damage is important.... When your blood oxygen falls below a certain level, the result is called hypoxemia. The symptoms of hypoxemia include extreme shortness of breath, headache, confusion and restlessness." - <a href="https://lunginstitute.com/blog/oxygen-and-brain-damage/" rel="nofollow">https://lunginstitute.com/blog/oxygen-and-brain-damage/</a><p>"The coronavirus damages both the wall and lining cells of the alveolus as well as the capillaries. The debris that accumulates because of all of that damage lines the wall of the alveolus the same way paint would cover a wall...." - <a href="https://health.clevelandclinic.org/heres-the-damage-coronavirus-covid-19-can-do-to-your-lungs/" rel="nofollow">https://health.clevelandclinic.org/heres-the-damage-coronavi...</a>