Background Exposure to secondhand smoke (SHS) has serious adverse health effects on adults and children, causing more than 600,000 deaths each year worldwide. Estimates of prevalence of non-smokers exposed to SHS range between 20% and 60% in various European countries. The WHO recommend to develop smoke-free policies to protect non-smokers from SHS exposure. E-cigarettes have irrupted in the market over the last 5 years, and their sales and popularity have considerably grown in the European Union (EU). Approximately 7% of Europeans ever used e-cigarettes. TackSHS is a new research project funded by the European Commission (EC) within the Horizon 2020 programme (grant agreement: 681040). Within the TackSHS Project, selected work packages (WP; i.e., WP3, WP9 and WP10) involve the conduction of a survey in 12 EU countries: the TackSHS survey.