Maria Sofia Cattaruzza

Families play a primary role in protecting children. Thirdhand smoke (THS) is an underestimated public health issue, and health effects correlated to its exposition are emerging. The aim of this systematic review was to analyze papers focusing on knowledge, beliefs, and behaviors regarding THS among parents, families, and caregivers, published until May 2022 on MEDLINE, CINAHL, EMBASE, and the Cochrane Library. Critical appraisal of the included studies was conducted by two independent reviewers using the Joanna Briggs Institute Critical Appraisal tool. Out of the 97 articles, 8 were included in this review (two from the USA, one from Europe, and five from Asia). Although there were no restrictions on the date of publication, all the articles were published in the last 10 years, underlining that THS is an emerging concept. They were characterized by relevant heterogeneity in the study design and assessment tools. The results showed that percentages of parents who believed that THS is harmful ranged from 42.4% to 91%, but parental awareness was not always associated with the adoption of a home- and car-smoking ban or healthy behaviors. Further research is needed to understand the resistance and problems faced by parents who are aware of THS risks but unable to improve good practices.