Objective To study a novel intervention (REFRESH) aimed at reducing children's exposure to secondhand smoke (SHS) in their homes.

Design A randomised feasibility study.

Setting Aberdeen City and Aberdeenshire.

Participants A total of 59 smoking mothers with at least one child younger than 6 years. Participation took place between July 2010 and March 2011.

Intervention Four home visits over a 1-month period, which involved two 24-h measurements of home air quality (PM_2.5) and a motivational interview to encourage changes to smoking behaviour within the home in order to reduce child SHS exposure. The enhanced group received their air quality data as part of their motivational interview at visit 2; the control group received that information at visit 4.

Main outcome measures The main outcome measures were comparisons of the data from visits 2 and 4 on the 24-h average concentration of PM_2.5, the peak concentration of PM_2.5, the percentage of time when household PM_2.5 concentrations exceeded a health-based threshold of 35 μg/m³ and child's salivary cotinine (in nanograms per millilitre). The views of the mothers from the enhanced group about their understanding of the intervention and the measures used were also analysed to assess the acceptability and utility of the intervention.

Results Of the recruited 54 participants, 48 completed the study: 27 from the control group and 21 from the enhanced group. Both groups experienced reductions in PM_2.5 concentrations. When testing paired samples for the enhanced group, there was a significant difference (p<0.05) between visit 2 and visit 4 values for maximum PM_2.5 (p=0.006) and for percentage of time over 35 μg/m³ (p=0.017), with average PM_2.5 approaching significance (p=0.056). There was no significant difference for salivary cotinine. The qualitative findings showed that mothers were able to understand the data they were shown and were shocked by the values measured in their homes despite being aware of the effects of SHS exposure. They appreciated the intervention taking place in their homes as it allowed them to have personalised data. Many mothers described how they had changed their smoking behaviours in their home and in particular were motivated to protect their own children as a result of the knowledge they had gained.

Conclusions Providing mothers who smoke with personalised results about the indoor air quality of their homes along with a motivational interview is feasible and has an effect on improving household air quality. Participants found the intervention understandable and acceptable. Taken overall, the results suggest that a future large-scale trial using measurements of indoor air quality as part of a complex intervention to reduce children's SHS exposure should be explored.