It can be conducted in primary care physicians' offices that are equipped with a spirometer. Patients take a deep breath and exhale into the spirometer as hard and fast as they can for a minimum of six seconds. The spirometer is connected to a computer that records the volume of air exhaled in one second (forced expiratory volume in one second, or FEV1) and the total amount of air exhaled (forced vital capacity, or FVC). The FEV1/FVC ratio is the primary measurement in identifying an obstructive impairment of the airways.