How long can a person live with only a fifth of one lung and does nothing to try and get better?

Is the other lung ok: I have a patient who has only one lung the other collapsed doing well. You need to do incentive spirometry - blow into a small tube to increase the amount of time to hold breath. Take n-acetyl cysteine to improve cell energy in lungs.

Residual Lung: Longevity after lung resection is based on a number of factors including baseline lung function, activity level, and residual lung volume. There are patients that can live decades after removal of a whole lung (pneumonectomy) and patients who live only months after a partial lung resection.