Background:
In Europe, more than half of smokers started before 18. Tobacco-free school policies (TFSP) were implemented as school plays a decisive role in smoking. Yet, there is inconclusive evidence that such policies are effective, as there are few well-designed and long-term experimental studies. In this study protocol, we describe the ADHAirE Project that aims to improve the implementation and effectiveness of TFSP.

Methods:
We will conduct a randomized controlled trial with 10 secondary schools in the experimental group and 10 secondary schools in the control group to test the effectiveness of the project on different smoking outcomes. The project will take place in the Hainaut province, which has the lowest income level and one of the highest smoking prevalence in Belgium. It is composed of three main components: regular evaluation of the school’s situation regarding its tobacco policy and adolescent smoking, creation of an advocacy coalition, and support provision regarding the implementation of the policy. Collaboration with smoking cessation programs will also be provided. A survey will be conducted among school staff and students at baseline, one-year, and two-year follow-up to collect data on smoking status and perceived smoking norm at school.

Discussion:
The project aims to make TFSP a social norm that is shared and enforced by a large coalition of school stakeholders, improve its implementation fidelity, and, ultimately, prevent and decrease adolescent smoking. The advocacy coalition will allow to gather stakeholders like principals, teachers and students to share reasons and beliefs to move toward a new “non-smoking norm”. As smoking is socially embedded, adolescents have to feel that they do not act alone when changing a common behavior. Similarly, school staff has to feel confident to enforce the TFSP. Findings from this project will contribute to the existing literature on school-based interventions and on adolescent smoking prevention.