title: Exposure to secondhand smoke and academic performance in non-smoking adolescents.
abstract: OBJECTIVE
  To study the association between exposure to secondhand smoke (SHS) and academic performance in non-smoking adolescents.
  
  
  METHODS
  A questionnaire survey of 23 052 non-smoking students aged 11 to 20 years was conducted. Information on academic performance, number of days of SHS exposure per week at home and outside the home, number of smokers at home and their relationship with the student, and sociodemographic characteristics was recorded.
  
  
  RESULTS
  Students exposed to SHS at home 1 to 4 and 5 to 7 days per week were 14% (95% confidence interval, 5%-25%) and 28% (15%-41%) more likely, respectively, to report poor academic performance compared with students who were not exposed to SHS. Living with one, two, and ≥ 3 smokers, compared with no smoker, was also associated with 10% (0.1%-20%), 43% (23%-65%) and 87% (54%-127%), respectively, higher odds of poor academic performance (P for trend <.001). The greatest excess risks were observed with SHS exposure from co-residing non-relatives, followed by siblings, visitors, co-residing grandparents and relatives, and parents.
  
  
  CONCLUSIONS
  SHS exposure is associated linearly with poor academic performance in non-smoking adolescents, and the effect of SHS exposure at home is stronger from smokers other than the parents.
authors.affiliation: School of Public Health, The University of Hong Kong, Pokfulam, Hong Kong.
authors.forename: Sai-Yin
authors.initials: SY
authors.lastname: Ho
authors.forename: Hak-Kan
authors.initials: HK
authors.lastname: Lai
authors.forename: Man-Ping
authors.initials: MP
authors.lastname: Wang
authors.forename: Tai-Hing
authors.initials: TH
authors.lastname: Lam
mesh_terms: D000293:Adolescent; D004522:Educational Status; D005260:Female; D006801:Humans; D019570:Inhalation Exposure / Q000009:adverse effects*; D008297:Male; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*
chemical_list: D014028:Tobacco Smoke Pollution