Influence of smoking on lung functions in young adults

Objectives: To determine the effect of smoking on forced vital capacity, forced expiratory volume in 1 sec. and the ratio between the two. Methods: The cross-sectional study was conducted in two Karachi-based medical colleges, Dow International Medical College and Bahria University Medical and Dental College between March 2010 and February 2011. The study comprised 244 male students (aged 19-25 years) who were selected by simple random sampling. A detailed questionnaire was got filled up by each participant to assess the smoking status and respiratory disease symptoms. Spirometry was performed by power lab spirometer according to the recommended guidelines of the American Thoracic Society and the European Respiratory Society by highly trained power lab instructor. Data was analysed using SPSS version 16. Means and standard deviations were worked out for continuous variables, while analyses of variance was done to see the difference among various categories. Results: A statistically significant difference was found in the mean spirometric values of forced expiratory volume, forced expiratory capacity and their ratio between the smokers and the non-smokers. The first two factors were significantly lower among those who smoked 10-20 cigarettes/day. But there was no statistically significant difference in the mean ratio of passive smokers and former smokers. Conclusion: The deterioration of lung functions and habitual cough is directly related to the number of cigarettes smoked per day in young smokers.