title: Respiratory effects of tobacco smoking among young adults.
abstract: BACKGROUND
  Respiratory symptoms associated with smoking habit seem to be age dependent. However, there are few reports about the effect of tobacco in young populations. The objective of this study was to analyze the effect of smoking on respiratory symptoms and lung function in 23- to 25-year-old adults in Brazil. This study had a cross-sectional design and included 2063 young people in the city of Ribeirão Preto, São Paulo State.
  
  
  METHODS
  Subjects completed a questionnaire used by the European Community Respiratory Health Survey and underwent spirometry and bronchial challenge test with methacholine. Multiple logistic regression analysis and multiple linear regression analysis were carried out to assess the association between smoking and respiratory symptoms, bronchial hyperresponsiveness, forced expiratory volume in 1 second (FEV1), and forced vital capacity (FVC), adjusted for confounding variables.
  
  
  RESULTS
  Prevalence of smoking habit was 17.2% with consumption (median) of 10 cigarettes per day (interquartile range 3-20). There was a significant association between smoking and respiratory symptoms. Smoking was associated to wheezing with odds ratio (95%CI) of 6.11 (4.03-9.28) among those smoking>or=10 cigarettes per day and 3.36 (2.11-5.37) among those smoking<10 cigarettes per day. Associations were found for other respiratory symptoms. Smoking was associated with lower FEV1/FVC ratio. No association was detected between smoking and FEV1 or bronchial hyperresponsiveness.
  
  
  CONCLUSIONS
  These findings highlight the early health consequences of smoking among young adults. These results prompt the necessity to elaborate urgent programs to reduce tobacco habit in young populations.
authors.affiliation: Department of Medicine, Medical School of Ribeirão Preto, University of S. Paulo, Ribeirão Preto, Brazil. evianna@uol.com.br
authors.forename: Elcio Oliveira
authors.initials: EO
authors.lastname: Vianna
authors.forename: Manoel Romeu Pereira
authors.initials: MR
authors.lastname: Gutierrez
authors.forename: Marco Antônio
authors.initials: MA
authors.lastname: Barbieri
authors.forename: Roseane Durães
authors.initials: RD
authors.lastname: Caldeira
authors.forename: Heloísa
authors.initials: H
authors.lastname: Bettiol
authors.forename: Antônio Augusto Moura
authors.initials: AA
authors.lastname: Da Silva
mesh_terms: D000293:Adolescent; D000328:Adult; D001938:Brazil; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D012137:Respiratory System / Q000503:physiopathology*; D012907:Smoking / Q000503:physiopathology*; D014026:Nicotiana