title: Effects of cigarette smoking intensity on the mucociliary clearance of active smokers.
abstract: BACKGROUND
  Smoking impairs mucociliary clearance and increases respiratory infection frequency and severity in subjects with and without smoking-related chronic lung diseases.
  
  
  OBJECTIVE
  This study evaluated the effects of smoking intensity on mucociliary clearance in active smokers.
  
  
  METHODS
  Seventy-five active smokers were grouped into light (1-10 cigarettes/day; n = 14), moderate (11-20 cigarettes/day; n = 34) and heavy smokers (≥21 cigarettes/day; n = 27) before starting a smoking cessation programme. Smoking behaviour, nicotine dependence, pulmonary function, carbon monoxide in exhaled air (exCO), carboxyhaemoglobin (COHb) and mucociliary clearance measured by the saccharin transit time (STT) test were all evaluated. An age-matched non-smoker group (n = 24) was assessed using the same tests.
  
  
  RESULTS
  Moderate (49 ± 7 years) and heavy smokers (46 ± 8 years) had higher STT (p = 0.0001), exCO (p < 0.0001) and COHb (p < 0.0001) levels compared with light smokers (51 ± 15 years) and non-smokers (50 ± 11 years). A positive correlation was observed between STT and exCO (r = 0.4; p < 0.0001), STT and cigarettes/day (r = 0.3, p = 0.02) and exCO and cigarettes/day (r = 0.3, p < 0.01).
  
  
  CONCLUSIONS
  Smoking impairs mucociliary clearance and is associated with cigarette smoking intensity.
authors.affiliation: Department of Physiotherapy, São Paulo State University, Presidente Prudente, São Paulo, Brazil.
authors.forename: Rafaella Fagundes
authors.initials: RF
authors.lastname: Xavier
authors.forename: Dionei
authors.initials: D
authors.lastname: Ramos
authors.forename: Juliana Tiyaki
authors.initials: JT
authors.lastname: Ito
authors.forename: Fernanda Maria Machado
authors.initials: FM
authors.lastname: Rodrigues
authors.forename: Giovana Navarro
authors.initials: GN
authors.lastname: Bertolini
authors.forename: Mariangela
authors.initials: M
authors.lastname: Macchione
authors.forename: Alessandra Choqueta
authors.initials: AC
authors.lastname: de Toledo
authors.forename: Ercy Mara Cipulo
authors.initials: EM
authors.lastname: Ramos
mesh_terms: D000328:Adult; D002248:Carbon Monoxide / Q000032:analysis; D002263:Carboxyhemoglobin / Q000032:analysis; D016022:Case-Control Studies; D045853:Exhalation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009079:Mucociliary Clearance / Q000502:physiology*; D012439:Saccharin / Q000493:pharmacokinetics; D012907:Smoking / Q000503:physiopathology*; D013147:Spirometry; D013549:Sweetening Agents / Q000493:pharmacokinetics
chemical_list: D013549:Sweetening Agents; D002248:Carbon Monoxide; D002263:Carboxyhemoglobin; D012439:Saccharin