What is Expiratory Reserve Volume (ERV)?

Expiratory Reserve Volume (ERV) is the additional air a person can forcibly exhale after a normal tidal volume exhalation. In other words, the maximum volume of air that can be breathed out forcefully after a normal breath. ERV is one of the lung volumes measured in pulmonary function tests and is part of the respiratory system parameters used to assess lung function. The respiratory system has various volumes and capacities describing different breathing aspects. ERV specifically pertains to the extra air that can be expelled from the lungs during forced exhalation. It is vital in maintaining respiratory efficiency and lung function.