Is it possible to reduce smoking at Danish vocational high schools?

INTERVENTION: Block randomization will be performed using a computer‐generated random number list prepared by an investigator with no involvement in the trial. Groups will be randomly allocated to intervention or comparison groups (1:1) with stratification for type of school (social and health care programs, commercial programs and technical or combination programs). Comparison schools continue with normal practice. The trialists will recruit schools sequentially; in August 2018 (for the autumn semester of 2018), and in August 2019 (for the autumn semester of 2019). They will use an adaptive design. Based on baseline data collected in the autumn semester of 2018, the design is adapted leading to redetermination of the trial’s sample size. For the three following reasons, there is uncertainty about the ability to recruit schools: 1. Implementing smoke‐free school policy (i.e., no smoking during school hours) may refrain schools from enrollment in the study. 2. Vocational education in Denmark is offered by about 80 schools and many schools are organized in large units (i.e., campus), which necessitate close collaboration between different organizations, and reduce the number of units available for enrollment. 3. Two patient organizations have received a large grant for implementing smoke‐free school policy (i.e., no smoking during school hours) at Danish vocational schools; the schools may prefer this project because they do not need to use resources on research‐based activities (i.e., time spend on fulfilling questionnaire, the uncertainty of randomization etc.). This multi‐component intervention is based on ecological frameworks suggesting that behavior can be influenced on multiple levels including individual, social, organizational, and policy. The intervention will comprise five areas aimed at: School‐level: 1. School smoking policy ‐ enforcement of a smoke‐free school policy (i.e., staff and students are not allowed to smoke during school hours) composed by the sc CONDITION: Smoking prevention and reduction ; Not Applicable PRIMARY OUTCOME: Self‐reported number of cigarettes per day, assessed by student questionnaire at baseline and post‐intervention (intervention and comparison groups). The trialists also plan to undertake 6 and 12 month follow‐up. However, this will only be reported if the response rate is acceptable. ; INCLUSION CRITERIA: Schools: 1. Are vocational high schools 2. Have students in basic course classes Students: 1. Entering the basic course of a vocational upper‐secondary education 2. Are in a school and a class participating in the study SECONDARY OUTCOME: Student outcomes, measured by questionnaire unless otherwise stated, at baseline and 4 months (at the end of the semester) (intervention and comparison groups). The trialists also plan data collections at 10 and 16 months; however, this will only be reported if the response rate is acceptable: ; 1. Self‐reported smoking status ; 2. Self‐reported intention to quit smoking/not to take up smoking; 3. Self‐reported nicotine dependence according to the Heavy Smoking Index (HSI) ; 4. Self‐reported smoking during school hours; 5. Perceived social norms about smoking ; 6. Smoking cessation self‐efficacy/refusal skills (among smokers); 7. Beliefs about social and psychological benefits of smoking; 8. Perceived student and teacher support; 9. School connectedness; 10. Perceived access to smoking cessation support ; 11. Acceptability of intervention components (student responsiveness); 12. Self‐reported use of e‐cigarettes, snuff, or hookah; 13. School dropout (register‐based); ; Teacher outcomes, measured by questionnaire at baseline and 2 months (only the intervention group):; 1. Self‐reported smoking status; 2. Perceived social norms regarding smoking at school; 3. Implementation readiness (motivation, general capacity, specific capacity) (pre‐intervention); 4. Level of implementation fidelity (adherence, dose, quality, responsiveness) (post‐intervention); ; Principal outcomes, measured by questionnaire at baseline and 4 months (only the intervention group):; 1. Implementation readiness (motivation, general capacity, specific capacity) (pre‐intervention); 2. Level of implementation fidelity (adherence, dose, quality, responsiveness) (post‐intervention); ; The primary and secondary student outcome measures will be analyzed for different subpopulations defined by gender, age and socioeconomic position (student questionnaire) and by implementation readiness and degree of implementation (principal questionnaire and teacher questionnaire).; ; Sustainability: whether the project continues at intervention schools and is initiated at control schools.