A spirometry test is a pulmonary function test that measures the quantity and speed of air you can exhale forcefully from your lungs. It helps your physician assess the extent of narrowing or obstruction of your airways.

A spirometry test uses a filtered mouthpiece attached via a tube to a spirometer, which measures airway flow. This test, done in the Pulmonary Function Lab, takes about 30 minutes. It can be performed alone or as part of a full pulmonary function test (PFT), which can take up to 60 minutes.