Ventilatory lung function following two years of tobacco abstinence.

Spirometry, maximal expiratory flows and the nitrogen closing volume test were studied in 59 subjects following their attempt to give up smoking. Seventeen subjects were tobacco abstinent for at least 5 months. This group showed significant improvement of vital capacity (VC), forced expiratory volume in 1 sec (FEV1) and the slope of phase III. Nine of these subjects remained ex-smokers for at least 24 months. However, no significant improvement of any of the measured variables could be established in this group. This may be due to the small number in the group and the circumstance that they were older and had worse lung function before smoking cessation compared with those who resumed smoking.