What does a pulmonary function test measure?

A pulmonary function test is designed to measure how well the lungs are functioning. This includes assessing lung capacity, which refers to the maximum amount of air the lungs can hold, as well as how effectively air moves in and out of the lungs during normal breathing. By measuring various aspects of lung function, such as forced vital capacity (FVC) and forced expiratory volume (FEV1), these tests help evaluate conditions such as asthma, chronic obstructive pulmonary disease (COPD), and other respiratory disorders.

The other choices do not accurately capture the primary focus of a pulmonary function test. Allergic reactions to airborne substances involve different diagnostic methods such as skin tests or blood tests. Cellular activity in lung tissues is more closely related to histological examinations rather than the functional capacity of the lungs. Lastly, while oxygen exchange efficiency is a crucial aspect of lung function, it is typically evaluated through arterial blood gas testing rather than through a standard pulmonary function test. Therefore, the emphasis of the pulmonary function test on measuring lung capacity directly supports the selection of this choice.