Determining the prevalence of people's knowledge that third‐hand smoke is harmful to health: A meta‐analysis study

Introduction Although the health effects of first‐hand smoke and second‐hand smoke are well known, third‐hand smoke (THS) is a relatively new concept. We estimated the prevalence of people's knowledge that THS is harmful to health, including for some subgroups, in a meta‐analysis. Methods We searched PubMed, Web of Science, Scopus, EBSCO Host, ProQuest, and YOKTEZ databases for the prevalence of people's knowledge that THS is harmful to health using specified search words. A total of 12 publications (n = 8549 people) were included in the meta‐analysis. The random effect model was used for meta‐analysis, and Cochran's Q test and I2 values were used to determine heterogeneity. Subgroup analyzes and meta‐regression were also performed. Results The prevalence of people's knowledge that THS is harmful was 80.1%. The prevalence of people's knowledge that THS is harmful for children was 82%, and the prevalence of people's knowledge that THS is harmful for adults was 70.4%. For health professionals, the prevalence of people's knowledge that THS is harmful for children was 89.8%, the highest prevalence value calculated in this meta‐analysis. Cochran's Q test and I2 values indicated that the included studies were heterogeneous. Conclusions In this meta‐analysis, the overall prevalence of people's knowledge that THS is harmful was 80.1%, but large variations were found between samples.