Vital capacity is the maximum volume of air a person can breathe in after a forced expiration. It is the sum of Inspiratory reserve volume (IRV), Expiratory reserve volume (ERV) and the Tidal volume (TV).
The vital capacity is different for different person. Its higher in athletes than in non-athletes, in mountain dwellers than in people living on plains and in youth than in old age. Cigarette smoking reduces the vital capacity.
