Introduction:
In this study we combined quantitative and qualitative data to: 1) describe the compliance of outdoor hospitality venues with smoke-free laws, and compare SHS levels in these settings according to their compliance; 2) explore perceptions and experiences among hospitality workers about the use of terraces in relation to tobacco consumption in these settings.

Methods:
This is a mix methods study conducted in the city of Madrid, Spain, in two phases. In phase 1 we conducted direct observation at outdoor terraces in hospitality venues to explore compliance with the smoke-free legislation, and measured PM2.5 concentrations. In phase 2 we conducted in-depth interviews with hospitality workers to provide insights on the phenomena behind our quantitative findings.

Results:
We measured PM_2.5 concentrations in 92 outdoor terraces. 21 of them were uncompliant with the law (have a roof and more than two sidewalls, and there were people smoking during the measurement). PM_2.5 concentrations were significantly higher in those terraces that were uncompliant (15.08 vs 9.36 µg/m³, p=0.001). We conducted 7 in-depth interviews with hospitality workers. Six of them worked in terraces that were uncompliant with the law and all of them did not know the regulation. All hospitality workers agreed that most customers believe that outdoor terraces are places for smokers, and they have the right to smoke there. Few of them have experienced complaints by non-smokers, and in that cases they offered them to move inside the venue.

Conclusion:
There is a need for tobacco control interventions in outdoor terraces of hospitality venues to protect hospitality workers, and users from SHS.