@gigiv It isn't just that the airways are widened. They lose their elasticity which means that their elastic recoil is diminished and the airways become floppy. The pathway through which air travels is then grossly decreased. Trying to cough up mucus causes the floppiness to further block the airway. Some airways become completely blocked with mucus and without oxygen they become stagnant and non functional. Removing the damage, as you suggest, can mean removing large branch-like areas of the lung. It isn't just a few cells. It isn't as simple as removing the damage and replacing it with healthy cells.