The purpose of this study was to develop new prediction equations for flow/volume spirometry parameters in asymptomatic, never-smoking adults in Norway, and to assess any differences of these parameters when applying the new and most commonly used equation sets.Flow/volume spirometry was measured according to the American Thoracic Society criteria in 2,792 subjects aged ¢20 yrs, randomly selected from participants in the Nord-Trøndelag Health Study. Ever-smokers and subjects with respiratory symptoms and/or diseases reported in this questionnaire were excluded. A total of 546 females and 362 males met the inclusion criteria and were included in the analyses.Most lung function variables were nonlinear by age and had to be transformed. After a plateau in younger adults, the variables declined by age. The reference values for forced expiratory volume in one second and forced vital capacity from the present study, were higher than those given by prediction equations from the European Community for Coal and Steel, but in closer agreement with later studies from Europe, Australia and the USA.Healthcare providers should be encouraged to reconsider their choice of prediction equations of spirometry in order to improve management of obstructive lung diseases.

Studies have indicated that females are more vulnerable to the deleterious effect of tobacco smoking than males. The current study aimed to investigate the associations between tobacco smoking and reported respiratory symptoms, self-rated health, and lung function by sex.In 1995-1997 65,225 subjects aged o20 yrs (71% of invited) attended for screening within the Nord-Trøndelag Health Study. Among these, 10,941 subjects selected randomly or because they reported having asthma or asthma-related symptoms, participated in the Bronchial Obstruction in Nord-Trøndelag study consisting of spirometry and a personal interview.Tobacco smoking was associated with increased prevalence of respiratory symptoms, reduced lung function, and lower score on global self-rated health (SRH). Adjusted for smoking burden and lung function, females had a higher risk for reporting respiratory symptoms and lower SRH compared with males. Further, smoking burden was associated with a larger relative reduction in expiratory lung function in females than in males.Females reported more symptoms and lower self-rated health compared with males with similar smoking burden. Even if smoking in females was associated with a larger reduction in per cent predicted lung function compared with males, this does not fully explain the higher symptom prevalence in females.

Associations between adolescent smoking habits and exercise, particularly participation in sports and lung function were studied.All students aged 13-19 yrs in Nord-Trøndelag County, Norway, 1995, were invited to join a cross-sectional study. Information on smoking habits and exercise was obtained by self-administered questionnaire. Spirometry was performed in accordance with American Thoracic Society standards.Of the 6,811 students (aged 13-18 yrs, without asthma), 2,993 (44%) reported neversmoking, and 1,342 (20%) reported current smoking (10% daily). Frequency of physical exercise was inversely associated with smoking, but participants in individual sports with lesser endurance, especially body-building and fighting sports, were more likely to be daily smokers than nonparticipants. Both daily (53%) and occasional smokers (43%) were more likely to have quit sports than never-smokers (26%). Never-smokers showed a positive dose-response between physical exercise and lung function (forced vital capacity and forced expiratory volume in one second, adjusted for age and height). No similar significant association was observed in daily smokers.These data suggest that smoking habits in different sports should be considered when promoting physical activity as smoking prevention, and sports organizations should include smoking prevention programmes. Adolescents with better lung function may self-select into sports; this possibility needs to be studied in a longitudinal design.

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