Introduction:
To evaluate the effect of telling undergraduate smokers their lung ages on the rate of smoking cessation.

Methods:
This randomized controlled study involved 142 eligible volunteer current undergraduate smokers. They were randomly allocated to the study group (group 1; n = 72) and the control group (group 2; n = 70). Participants in group 1 were told their lung age, received a 5-minute motivational interview, and were given raw figures of their pulmonary function, while participants in group 2 received the same intervention except the lung age. Initially (evaluation 1), the subjects’ lung ages were estimated through spirometric assessment of forced expiratory volume in 1 second. The number of smoked cigarettes per day was reported and the smoking status was ensured through the assessment of exhaled carbon monoxide at evaluation 1, after 6 months (evaluation 2), and after 12 months (evaluation 3).

Results:
At evaluation 2, the overall follow-up rate was 95.07%. There was a significant difference in the smoking quit rate between group 1 (23.61%) and group 2 (10%) (p = 0.03). At evaluation 3, no change existed in the follow-up rate. The smoking quit rate was 19.4% and 4.3% for groups 1 and 2, respectively (p = 0.01).

Conclusions:
Telling undergraduate smokers their lung ages can significantly improve the smoking quit rate in a short- and long-term perspective. The long-term partial relapse status arouses the question about other contributing factors out of the scope of this study.