Lung function measurement
This measurement is called spirometry. The volunteer is breathing out into a machine (spirometer) which records the breathing out (expiration).
You can tell a lot from the trace that is shown on the screen. Some of the measurements from this trace are very useful as simple measures of lung health and are also used for diagnosing lung disease (especially a disease called COPD). Two measurements we use are:
(1) the total amount (volume) of air that you can breathe out (also called forced vital capacity or FVC) and;
(2) the amount (volume) of air that you can breathe out in one second (also called the forced expiratory volume in 1 second or FEV1).