Proportion of middle and high school students who reported being exposed to indoor secondhand smoke within the past 7 days, National Youth Tobacco Survey, United States, 2000–2009.

Note: All percentages were weighted to adjust for differential non-response and selection; n = unweighted samples; CI = Confidence Interval.*Current cigarette smokers were students who reported that they had smoked cigarettes on at least one day within the past 30 days preceding the survey.†Statistically significant linear trend (p