Decrease in ventilatory capacity between ages of 50 and 54 in representative sample of Swedish men.

The ventilatory capacity, including flow-volume curves of 313 men, all 50 years old, was examined in 1963 and 1967. The group as a whole, which included persons with chronic bronchitis, with "other respiratory symptoms," and without respiratory symptoms, showed the same absolute decrease in ventilatory capacity.Vital capacity, forced expiratory volume, and maximum expiratory flow all dropped more for the smokers than for either the non-smokers or the ex-smokers. In those who had stopped smoking for four years or less, however, ventilatory capacity did not decline significantly less than in those who continued to smoke.