Spirometry is the most common of the lung function tests. These tests look at how well your lungs work. Spirometry measures the volume of air and the speeds at which that air can be inhaled and exhaled. The most common measurements used are: Forced expiratory volume in one second (FEV1). This is the amount of air you can blow out within one second.

With normal lungs and airways you can normally blow out most of the air from your lungs within one second. Forced vital capacity (FVC). The total amount of air that you blow out in one breath. FEV1 divided by FVC (FEV1/FVC). Of the total amount of air that you can blow out in one breath, this is the proportion that you can blow out in one second. In asthma the FEV1/FVC is typically lower than normal.



Take a look at the videos below which demonstrate spirometry testing: