title: Association of mechanical ventilation and flue use in heaters with asthma symptoms in Japanese schoolchildren: a cross-sectional study in Sapporo, Japan.
abstract: BACKGROUND
  Use of fuel heaters is associated with childhood asthma. However, no studies have evaluated the associations of flue use and mechanical ventilation (ventilation) with asthma symptoms in schoolchildren.
  
  
  METHODS
  This cross-sectional study investigated schoolchildren in grades 1 through 6 (age 6-12 years) in Sapporo, Japan. From November 2008 through January 2009, parents completed questionnaires regarding their home environment and their children's asthma symptoms.
  
  
  RESULTS
  In total, 4445 (69.5%) parents of 6393 children returned the questionnaire. After excluding incomplete responses, data on 3874 children (60.6%) were analyzed. The prevalence of current asthma symptoms and ever asthma symptoms were 12.8% and 30.9%, respectively. As compared with electric heaters, current asthma symptoms was associated with use of flued heaters without ventilation (OR = 1.62; 95% CI, 1.03-2.64) and unflued heaters with ventilation (OR = 1.77; 95% CI, 1.09-2.95) or without ventilation (OR = 2.23; 95% CI, 1.31-3.85). Regardless of dampness, unflued heaters were significantly associated with current asthma symptoms in the presence and absence of ventilation.
  
  
  CONCLUSIONS
  Use of unflued heaters was associated with current asthma symptoms, regardless of dampness. In particular, the prevalence of current asthma symptoms was higher in the absence of ventilation than in the presence of ventilation. Ever asthma symptoms was only associated with use of unflued heaters without ventilation. Consequently, use of fuel heaters, especially those that have no flue or ventilation, deserves attention, as their use might be associated with childhood asthma symptoms.
authors.affiliation: Hokkaido University Graduate School of Medicine, Department of Public Health Sciences.
authors.forename: Shi
authors.initials: S
authors.lastname: Cong
authors.forename: Atsuko
authors.initials: A
authors.lastname: Araki
authors.forename: Shigekazu
authors.initials: S
authors.lastname: Ukawa
authors.forename: Yu
authors.initials: Y
authors.lastname: Ait Bamai
authors.forename: Shuji
authors.initials: S
authors.lastname: Tajima
authors.forename: Ayako
authors.initials: A
authors.lastname: Kanazawa
authors.forename: Motoyuki
authors.initials: M
authors.lastname: Yuasa
authors.forename: Akiko
authors.initials: A
authors.lastname: Tamakoshi
authors.forename: Reiko
authors.initials: R
authors.lastname: Kishi
mesh_terms: D016902:Air Pollution, Indoor / Q000009:adverse effects; D001249:Asthma / Q000453:epidemiology*; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D005579:Fossil Fuels / Q000009:adverse effects; D006361:Heating / Q000009:adverse effects* / Q000295:instrumentation*; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D015995:Prevalence; D012621:Seasons; D011795:Surveys and Questionnaires; D014691:Ventilation
chemical_list: D005579:Fossil Fuels
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