Pulmonology function tests are useful to check how well the lungs work. The most basic test is spirometry. The test measures the amount of air the lungs can hold. The test also measures how forcefully one can empty air from the lungs.

Spirometry is used to screen for diseases that affect lung volumes. It is also used to screen for diseases that affect the airways, such as COPD or asthma.

Lung volume testing is another commonly performed lung function test. It is more precise than spirometry and measures the volume of air in the lungs, including the air that remains at the end of a normal breath. In addition, a diffusing capacity test measures how easily oxygen enters the bloodstream. Exercise testing helps evaluate causes of shortness of breath. There are also tests to find out if asthma is present when the usual breathing test results are normal.