A pulmonary function test is a series of four breathing tests that measure how well your lungs take in and release air and how well they move gases, like oxygen, into the body. This test shows the presence and extent of lung abnormalities. It is also used to evaluate the need for inhalers and the effects of medication on the lungs.

The pulmonary function test is performed by a registered respiratory therapist (RRT). To learn more about this health professional, see College of Respiratory Therapists of Ontario – What is a Respiratory Therapist?

Download the pulmonary function test brochure.

To have a pulmonary function test, your doctor needs to fill out a requisition form.

Learn more about making an appointment and coming to our hospitals.

Before Your Pulmonary Function Test

Do not smoke for two to four hours before your test.

Important Information About Medications

If possible, please do not take any inhalers on the day of your test. If you require emergency rescue medication or inhalers, you may take those. Please notify the RRT doing your test if you took any inhalers.

During Your Pulmonary Function Test

During your test, the RRT will guide and coach you through a series of breathing tests. You will be in a glass booth that has a door which will be open during most of the tests and closed during only one test. You will have a nose clip and mouthpiece. You will be asked to take deep breaths in and out while performing the tests.

Frequently Asked Questions