Lung Function Tests Say: lung funk-shun tests How well do your lungs function? In other words, how well are you breathing? There are several tests that can help your doctor answer that question. For one of them, called spirometry, you take a breath and then blow the air out as fast and long as you can. These tests can help a doctor find out if someone has asthma. Back to Articles Related Articles Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995-2021 KidsHealth®. All rights reserved. Images provided by The Nemours Foundation, iStock, Getty Images, Veer, Shutterstock, and Clipart.com.