Objective: To understand the exposure to second hand smoking (SHS) and associated factors among middle school students in Beijing, and to provide data support for tobacco control. Methods: The two stage stratified cluster random sampling method were used to select 10 532 students from 370 classes in 48 junior middle schools, 34 senior high schools and 14 vocational high schools in 16 districts of Beijing. The national unified paper questionnaire was used to collect the information. Results: During the past 7 days, 71.5% (95% CI =70.2%-72.7%) of students reported exposure to SHS. The proportion of exposure was highest (60.3%) in outdoor public places, followed by indoor public places (48.9%), at home (34.1%), and public transport (19.1%). About 31.6% of students reported people smoking in the campus in the past 30 days. Risk factors of SHS exposure included one or more parents was smoker( OR =2.62), friends who smoked( OR =2.13), received education on tobacco hazards in school( OR = 0.74 ), and senior high school( OR =0.68-0.73)( P <0.05). Conclusion High exposure to second hand smoking among middle school students in Beijing is common. Implementation of the regulations and the publicity of tobacco hazards and tobacco control in schools should be strengthened. Smoke free household should be advocated, and middle school students, especially junior middle school students, should be protected from the harm of SHS.

Objective: To analyze the second hand smoke exposure and related factors of nonsmoking junior middle school students in Beijing, so as to provide a data support for formulating tobacco control measures. Methods: The multistage cluster random sampling method was used to select junior middle school students in Beijing. The valid data of 4 494, 4 915 and 3 792 nonsmoking middle school students were obtained from three waves of youth tobacco epidemic surveillance in 2013 (September to October), 2019 (August to November) and 2021 (September to December) wave, respectively. The information was collected by the national youth tobacco epidemic surveillance questionnaire. The complex sampling data analysis module of SPSS 21.0 was used to descriptive analysis and multivariate Logistic regression. Results: The proportions of secondhand smoke exposure of nonsmoking junior middle school students in the four types of places in the past 7 days in 2013, 2019 and 2021 in Beijing were 76.4%, 71.4% and 65.7%, respectively, with statistically significant differences (χ2=126.10, P<0.01). The proportions of that found someone smoking in the campus in the three waves of survey were 34.7%, 27.9% and 21.1% (χ2=209.78), the proportion of that found teachers smoking daily were 2.7%, 1.8% and 1.3% (χ2=22.14) (P<0.01), respectively. Multivariate Logistic regression analysis showed both parents smoking (OR=8.47, 95%CI=4.36-16.48), father smoking (OR=3.51, 95%CI=2.75-4.49), and friends smoking (OR=1.88, 95%CI=1.39-2.55) were the influencing factors of secondhand smoke exposure in four types of places of nonsmoking junior middle school students in 2013. Both parents smoking (OR=2.37, 95%CI=1.33-4.22), father smoking (OR=2.80, 95%CI=2.33-3.37), friends smoking (OR=2.24, 95%CI=1.71-2.92), and teaching the tobacco hazards in class (OR=0.77, 95%CI=0.64-0.93) were the influencing factors of secondhand smoke exposure in four types of places for nonsmoking middle school students in 2019. Both parents smoking (OR=3.93, 95%CI=2.29-6.75), fathers smoking (OR=3.30, 95%CI=2.72-3.99), and teaching the tobacco hazards in the class (OR=0.81, 95%CI=0.68-0.97) were the influential factor of secondhand smoke exposure in four types of places of nonsmoking junior middle school students in 2021 (P<0.05). Conclusions The secondhand smoke exposure of nonsmoking middle school students in Beijing has improved, but still is a high level. It is necessary to take corresponding measures to effectively protect nonsmoking junior middle school students from the harm of secondhand smoke.

Objective: To monitor the second-hand smoke (SHS) exposure in residents aged 15 years and over in public venues, indoor workplaces, on public transportation vehicles and at home in Beijing and evaluate the effect of Beijing Tobacco Control Regulation. Methods: Data from 2014 and 2016 Beijing Adult Tobacco Survey were used. The surveys covered 16 districts in Beijing. The study subjects were selected through multi-stage cluster sampling with probability proportional to population size, and data were collected by using electronic questionnaire in face-to-face household interviews. A total of 8 484 and 9 372 valid questionnaires were collected for the surveys in 2014 and 2016, respectively. Statistical packages SPSS 20.0 and R 3.4.4 were used for data analyses. After weighting the samples using complex survey designs, the SHS exposure rates in different places in adults of Beijing were estimated. χ² tests were performed for the comparison. Results: The SHS exposure rates of residents aged 15 years and over in Beijing who visited health care facilities, government buildings, universities, primary and secondary schools and restaurants declined from 12.8%, 19.7%, 24.3%, 32.8% and 65.7% in 2014 to 6.2%, 10.8%, 12.5%, 19.1% and 32.5% in 2016, respectively. The SHS exposure rates in bars/nightclubs were 89.5% in 2014 and 80.3% in 2016. From 2014 to 2016, the SHS exposure rates declined from 35.7% to 20.0% in indoor workplaces and declined from 3.9% to 2.5% on public transportation vehicles. The SHS exposure rates at home were 39.8% in 2014 and 37.6% in 2016, respectively. Conclusions The SHS exposure rates in public places declined obviously in Beijing after the one year implementation of Beijing Tobacco Control Regulation, indicating the effect of the regulation implementation.