What are causes of low oxygen in elderly?

Not normal: As we age, our lungs become less elastic and with aging changes, there is less transfer of oxygen, so more likely to have low oxygen levels. However, healthy elderly will not manifest with low oxygen levels unless there is underlying lung disease(ie emphysema) or an illness(ie pneumonia). If one is bedbound, there maybe less useable lung space, and lower oxygen levels may occur.

Cardiopulm disaese: Age related decline in lung function, copd, pulm fibrosis , chf.