Immediate Feedback Generates Greater Improvements In Secondhand Smoke Reduction For Dual Smokers Compared To Exclusive Tobacco Users

Secondhand smoke (SHS) exposure is defined as the breathing of smoke exhaled from burning combustible products, which can increase the risk of heart and lung diseases, especially in children. Research has primarily focused on tobacco SHS, with much less work examining cannabis SHS. Project Fresh Air, conducted in San Diego County, investigated the effect of real-time visual audio feedback plus coaching interventions on SHS, by gathering air particulate matter (PM2.5) data over the course of three months in the homes of 298 smokers in low-income households with children under 14 years of age. The sample consisted of participants who only smoked tobacco (n=163), as well as dual smokers of tobacco and cannabis (n=29), who were randomized into two groups: an intervention group that received real-time feedback, and a control group that did not. The goal of this study was to determine whether the intervention had differential effects on indoor air quality, measured by PM2.5, on participants who smoked only tobacco or were dual smokers. A three-way interaction multiple regression model looked at the change in PM2.5 before and after intervention, between tobacco smokers and dual smokers, and between intervention and control groups. We found that the main effect of the intervention decreased PM2.5 from baseline to post-intervention (B = -233.37, p = 0.01). Dual users had a higher PM2.5 concentration during the baseline compared to tobacco smokers (B = 1837.25, p < 0.001). Compared to baseline, the intervention group of dual smokers had a decrease in their PM2.5 by 1320.63, while tobacco smokers decreased theirs by 337.27 (p < 0.01). These results reveal that because marijuana users generated more SHS at baseline, which gives them more room to improve, resulting in more significant air pollution reduction after intervention.