title: Socio-demographic correlates of exhaled breath carbon monoxide in Karachi's adult population.
abstract: OBJECTIVE
  To examine the relationship between CO levels and putative factors including smoking status among residents of Karachi, an urban center with very high levels of air pollution.
  
  
  METHODS
  Two hundred and eighteen volunteering subjects were asked to maximally exhale into a Smokerlyzer breath CO analyzer. Each of the volunteers was also asked to reply to a questionnaire-based interview seeking demographic information as well as details of exposure to tobacco, traffic fumes and other air pollutants.
  
  
  RESULTS
  Out of the 218 participating subjects, 75% were males and 27% were current or ex-smokers. The mean CO level was 2.92 parts per million (ppm). Cigarette smoking was the only factor found to influence CO levels. Number of cigarettes smoked per day was directly related to CO levels, while time since the last smoke was inversely related. There was no difference in CO levels between ex-smokers and never-been-smokers. Years of residence in Karachi, quantitative exposure to traffic and perception of occupational exposure to air pollutants were not associated with CO levels.
  
  
  CONCLUSIONS
  Smoking status, number of cigarettes smoked per day and time since last smoke correlated well with exhaled breath CO levels, in spite of high air pollution levels. This tool therefore continues to provide a valid and real-time assessment of a subject's current smoking status.
authors.affiliation: Section of Pulmonary and Critical Care, Department of Medicine. Aga Khan University, Karachi.
authors.forename: Majid
authors.initials: M
authors.lastname: Shafiq
authors.forename: Sumera
authors.initials: S
authors.lastname: Khan
authors.forename: M Rizwanulhaq
authors.initials: MR
authors.lastname: Khawaja
authors.forename: Suleman
authors.initials: S
authors.lastname: Haque
authors.forename: Javaid A
authors.initials: JA
authors.lastname: Khan
mesh_terms: D000328:Adult; D000367:Age Factors; D000393:Air Pollutants / Q000009:adverse effects*; D001944:Breath Tests; D002248:Carbon Monoxide / Q000032:analysis*; D003430:Cross-Sectional Studies; D003710:Demography; D045853:Exhalation; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D010154:Pakistan; D012907:Smoking / Q000009:adverse effects*; D012959:Socioeconomic Factors
chemical_list: D000393:Air Pollutants; D002248:Carbon Monoxide