title: Disparities and trends in indoor exposure to secondhand smoke among U.S. adolescents: 2000-2009.
abstract: BACKGROUND
  Secondhand smoke (SHS) exposure causes disease and death among nonsmokers. With a plethora of smoke-free legislation implemented and a steady decrease in cigarette consumption noted over the past decade in the U.S., this study assessed trends in indoor SHS exposure among U.S. adolescents in grades 6-12 during 2000-2009.
  
  
  METHODS
  Data were obtained from the 2000-2009 National Youth Tobacco Survey - a national survey of U.S. middle and high school students. SHS exposure within an indoor area within the past seven days was self-reported. Trends in indoor SHS exposure during 2000-2009 were assessed overall and by socio-demographic characteristics, using the Wald's test in a binary logistic regression. Within-group comparisons were performed using chi-squared statistics (p<0.05).
  
  
  RESULTS
  The proportion of U.S. middle and high school students who were exposed to indoor SHS declined from 65.5% in 2000 to 40.5% in 2009 (p<0.05 for linear trend). Significant declines were also observed across all population subgroups. Between 2000 and 2009, prevalence of indoor SHS exposure declined significantly among both middle (58.5% to 34.3%) and high school (71.5% to 45.4%) students. Prevalence of indoor SHS exposure was significantly higher among girls (44.0% in 2009) compared to boys (37.2% in 2009) during each survey year. Similarly, prevalence of indoor SHS exposure during 2000-2009 was highest among non-Hispanic whites (44.2% in 2009) and lowest among non-Hispanic Asians (30.2% in 2009). During each survey year, prevalence was highest among the oldest age group (≥18 years) and lowest among the youngest (9-11 years). Also, prevalence was significantly higher among current cigarette smokers (83.8% in 2009) compared to nonsmokers (34.0% in 2009).
  
  
  CONCLUSIONS
  Significant declines in indoor SHS exposure among U.S. middle and high school students occurred during 2000-2009. While the results are encouraging, additional efforts are needed to further reduce youth indoor SHS exposure.
authors.affiliation: Center for Global Tobacco Control, Department of Social and Behavioral Sciences, Harvard School of Public Health, Boston, Massachusetts, United States of America.
authors.forename: Israel T
authors.initials: IT
authors.lastname: Agaku
authors.affiliation: Center for Global Tobacco Control, Department of Social and Behavioral Sciences, Harvard School of Public Health, Boston, Massachusetts, United States of America.
authors.forename: Constantine I
authors.initials: CI
authors.lastname: Vardavas
mesh_terms: D000293:Adolescent; D000367:Age Factors; D016902:Air Pollution, Indoor / Q000706:statistics & numerical data*; D002648:Child; D004781:Environmental Exposure / Q000706:statistics & numerical data; D005260:Female; D054624:Health Status Disparities; D006801:Humans; D008297:Male; D057566:Self Report; D012907:Smoking / Q000453:epidemiology / Q000639:trends*; D013334:Students / Q000706:statistics & numerical data; D014028:Tobacco Smoke Pollution / Q000706:statistics & numerical data*; D014481:United States / Q000453:epidemiology
chemical_list: D014028:Tobacco Smoke Pollution