Outdoor secondhand smoke exposure in public places frequented by minors in the urban area of Hangzhou City, China: A cross-sectional study.

Introduction: Hangzhou Public Places Smoking Control Regulations (2019) have been gradually adopted, which explicitly stipulate that smoking is strictly prohibited in the outdoor areas of educational and healthcare institutions for minors. However, there are few studies reporting the exposure to secondhand smoke (SHS) in outdoor public places for minors in the urban area of Hangzhou City.

Methods: We aimed to assess the exposure to SHS in public spaces frequented by minors using on-site observations and questionnaires. In this cross-sectional study, the area was divided into core and non-core areas based on the spatial distribution and development process of the city. The core areas included the West Lake commercial district, extending to the Qiantang River, while non-core areas were located beyond this radius. Using stratified random sampling, 30 public places in each area were selected as observation sites. On-site observations measured SHS exposure and smoking control, and questionnaires were administered to 6 individuals at each site. The results were compared between the two investigation methods.

Results: Among the 57 valid observation points, 24.6% (14/57) did not display any no-smoking signs. Outdoor SHS exposure rate from on-site observation P1 (observing someone smoking or smelling tobacco smoke), on-site observation P2 (observing someone smoking or smelling tobacco smoke or seeing cigarette butts) and questionnaire survey P3, were 59.6% (95% CI: 45.7-72.2), 91.1% (95% CI: 79.7-96.7) and 41.0% (95% CI: 35.5-46.7), respectively.

Conclusions: The outdoor SHS exposure in areas frequented by minors in the urban district of Hangzhou City remains high, coupled with a lack of awareness of SHS risks among underage individuals. Therefore, controlling outdoor SHS exposure in these key areas is a critical public health issue in Hangzhou, requiring further tobacco control efforts. On-site observation is an important and supplementary research method to investigate outdoor SHS exposure, especially to describe the SHS exposure of focus areas.