Cannabis Secondhand Smoke Exposure: Perceived Harm, Household Rules, and In-Home Cannabis Smoking

Background: Cannabis smoke is often perceived as not harmful1,2 and is commonly allowed to be smoked indoors.3–5 The prevalence of household rules to ban in-home cannabis smoking is low6, and the prevalence of in-home cannabis smoking is high.7 Cannabis use continues to rise in some regions of the world as cannabis use laws are liberalized.8,9,10 There is a need to understand what drives in-home cannabis smoking, which leads to investigation of cannabis secondhand smoke (cSHS) exposure.Methods: In Aim 1, I used cross-sectional data from the Marijuana Use and Environmental Survey to quantify the association between perceived harm of cSHS exposure and having a complete ban on in-home cannabis smoking. In Aim 2, using cross-sectional data from the Global Drug Survey 2021, I quantified the association between perceived harm of cannabis smoke exposure and in-home cannabis smoking. In Aim 3, using baseline data from Project Fresh Air, an intervention study, I i) ascertained a novel variable representing in-home cannabis smoking using air particle data and self-reported indoor particle generating events through residualization, and ii) quantified the relationship between the ascertained in-home cannabis smoking variable and urinary cannabinoids in children’s urine.Results: In Aim 1, respondents who reported cSHS exposure as “extremely harmful” had 6 times the odds (OR=6.0, 95% CI=4.9-7.2) of having a complete ban on in-home cannabis smoking as those who reported cSHS exposure as “totally safe”. In Aim 2, a respondent at the 75th percentile of perceived harm of cannabis smoke had 70% higher odds (OR=1.7, 95%b CI=1.6-1.8) of having had no in-home cannabis smoking, compared to a respondent at the 25th percentile of perceived harm. In Aim 3, the odds of detectable urinary cannabinoids in children’s urine were five times (OR=5.0, 95% CI = 2.4-10.4) as high in households with reported in-home cannabis smoking compared to those without any in-home cannabis smoking.Conclusion: Perception of harm related to cannabis smoke exposure is instrumental in reducing in-home cannabis smoking through setting household rules, leading to reduced cSHS exposure at home. Advocacy and educational efforts to reduce cSHS exposure should develop tailored approaches to changing perceptions of cSHS harm.