You may be advised to take lung function tests to find out how much air moves in and out as you breathe.

The two most common tools used to measure lung function are spirometers and peak flow meters. 

Lung function tests are sometimes done before and after taking a medication known as a bronchodilator (asthma reliever medication) to open your airways.

Other more detailed lung function tests may be required in a special lung function laboratory. These may include exercise testing.