Human: What is a pulmonary function test? Assistant: 
A Pulmonary Function Test is a medical procedure that measures the amount of air you can breathe out and in. It’s used to diagnose and monitor lung diseases, such as COPD (Chronic Obstructive Pulmonary Disease) or asthma. The test is performed by breathing into a machine called a spirometer, which measures how fast and how much you are able to inhale and exhale.