Use of nicotine replacement therapy to reduce children's exposure to second-hand smoke in the home: Findings of a pilot randomised controlled trial conducted in Scotland Running title: Use of nicotine replacement therapy to create a smoke-free home

Citation

O'Donnell R, Mather K, Henderson T, Sinclair L, Howell R, Mcmeekin N & Semple S (2026) Use of nicotine replacement therapy to reduce children's exposure to second-hand smoke in the home: Findings of a pilot randomised controlled trial conducted in Scotland Running title: Use of nicotine replacement therapy to create a smoke-free home. medrxiv.org. https://doi.org/10.64898/2026.08.13.26360348

Abstract
Introduction: Children’s exposure to second-hand tobacco smoke is a preventable global public health issue, yet there is no consensus on how best to support families to create a smoke-free home. This pilot randomised controlled trial tested the feasibility of use of free nicotine replacement therapy combined with telephone-delivered support to reduce children’s exposure to second-hand smoke in the home, and inform a future full-scale trial. Methods: Parents/carers aged 18+ years, who smoke in the home and care for one or more children aged 0-16 years were recruited through existing initiatives and social media. Participants were randomised to either the intervention (Group A) or control (Group B) arm. Group A received free posted-to-home nicotine replacement therapy, alongside fortnightly telephone calls to support smoking abstinence in the home. Group B were signposted to the Scottish Government’s ‘Take it Right Outside’ website which provides interactive advice on creating a smoke-free home. To measure second-hand smoke levels, participants installed an air quality monitor in their living room for 7 days to measure fine particulate matter (PM2.5) at baseline and 12-week follow-up. Results: Approximately one-quarter (n=27/100) of the intended sample size was recruited. Median PM2.5 concentrations reduced in both the intervention (-36μg/m3) and control (-16mg/m3) groups. Retention rates and adherence rates to nicotine replacement therapy were 70% and above, with no risks and/or safety concerns reported, suggesting this approach is feasible and acceptable to participants. The estimated cost of delivering this 12 week intervention was £244 per individual. Conclusions: Although recruitment rates were insufficient to recommend progression to a larger trial to test effectiveness of this approach in Scotland, this study could inform trial development in other countries where smoking in the home is commonplace. Insights regarding the alignment of smoke-free home interventions with broader smoking cessation initiatives could inform future policy and public health approaches.