Lung function tests are a group of tests that measure how well your lungs and airways are working. 

Your doctor may order lung function testing if you;

• Already have a lung condition that requires monitoring

• Are noticing symptoms related to a respiratory illness

• Are suspected of having a lung condition

• Are preparing for surgery

• Are exposed to certain substances (in the environment or at work) that are linked with lung disease 

Lung function tests are non-invasive and safe and are relatively simple to perform. They do, however, require you to breathe in and out with maximum effort which may cause you to feel a little tired and puffed, but not uncomfortable or in pain.