The two lungs of each of us together have about 700 million alveoli, just like 700 million small balloons. Air enters these small balloons, oxygen diffuses into the blood, carbon dioxide diffuses in and is exhaled out of the body through the airway, achieving the purpose of exhaling. If several adjacent alveoli rupture, they fuse into one large alveolus, and if this large alveolus grows gradually to the point where it is visible on a chest radiograph or chest CT. Radiologists then report pulmonary blisters. Pulmonary blisters vary in size from a few millimeters to tens of centimeters, up to the size of one side of the lung. They can be single or multiple and cover both lungs. Do pulmonary blisters require treatment? Depends on how large the pulmonary blister is and how it affects lung function. If it is a large pulmonary blister that is compressing the surrounding normal lungs and affecting lung function, it can be surgically removed. If it is not large and has no effect on lung function, no treatment is needed. Lately, surgical resection can be achieved by tracheal placement of a one-way valve.