MODEL RELEASED. Lung function testing. Patient undergoing a type of test known as spirometry to assess the functioning of the lungs. She is blowing into a peak flow meter (spirometer), with the results displayed on the portable monitor at lower left. The spirometer measures the amount and speed of air that is exhaled. It is an important tool used for assessing conditions such as asthma, cystic fibrosis, and chronic obstructive airway diseases (COAD) such as bronchitis and emphysema, also collectively known as chronic obstructive pulmonary disease (COPD). Photographed in the UK.