[Lung function and exposure to tobacco smoke among adolescents]

To study lung function in adolescents in relation to smoking (active and passive smokers) and to investigate the repercussion on spirometric parameters.

We studied 301 healthy adolescents with no history of bronchial asthma or colds in the month prior to the study. A questionnaire on tobacco exposure was administered and spirometry (Datospir-92) was performed.

There were 165 boys (54.5%) and 136 girls (45.5%) aged between 14 and 20 years old (16.40+/-1.32). A total of 27.2% were non-smokers and were not exposed to tobacco smoke (NS), 31.3% were passive smokers, with household exposure of 10 cigarettes per day during at least the previous year (PS), and 41.5% were current smokers who had been smoking>or=10 cigarettes/day for at least 1 year (CS). Significant differences were found between age and smoking habits (p=0.0001) and between smoking habits and female sex (girls CS: 33.9% vs boys CS: 21.8 %) (p=0.007). A significant association was found between smoking (NS, PS and CS) and spirometric parameters (ANOVA): forced vital capacity (FVC) (p=0.001), forced expiratory volume in 1 second (FEV1) (p=0.0001), FEV1/FVC (p=0.004), peak expiratory flow (PEF) (p=0.0001), midexpiratory flow at 25% of forced vital capacity (MEF25%) (p=0.01), MEF50% (p=0.0001) and MEF25-75% (p=0.0001); CS in relation to NS was as follows: FEV1, PEF, MEF50%, MEF25-50% (p=0.0001) and FVC, FEV1/FVC, MEF25% (p=0.01); CS in relation to PS: FEV1/ FVC (p=0.02), PEF (p=0.004), MEF50% and MEF25-75% (p=0.003), PS in relation to NS: FVC and FEV1 (p=0.02). Significant differences in FVC, FEV1 and MEF25-75% were found in female CS in comparison with boys.

The CS group showed a significant decrease in spirometric parameters in relation to the NS group. The airway was affected sooner in the female group of smokers than in the male group, even though the intensity and time of exposure were the same in both groups.