People Who Think Secondhand Cannabis Smoke Is Harmful Are Less Likely to Smoke at Home | Research

The takeaway

In a 21-country survey of over 28,000 drug users, those who perceived secondhand cannabis smoke as more harmful had 70% higher odds of not smoking cannabis at home, suggesting harm perception may protect household members.

Public health campaigners, cannabis policy advocates, and harm reduction researchers

70% higher odds of no home smoking when harm perception is high

What the researchers found

Those at the 75th percentile (vs 25th) of perceived harm from secondhand cannabis smoke had 70% higher odds (OR=1.7) of reporting no in-home cannabis smoking. The association held across all 21 countries, with the strongest effects in Sweden (OR=3.9) and New Zealand (OR=2.3). Mean perceived harm was 5.2 on a 10-point scale. 61% reported no in-home cannabis smoking.

Why it matters

As cannabis legalization expands, most smoking occurs at home, exposing household members to secondhand smoke. If harm perception drives behavior change, public health campaigns emphasizing secondhand cannabis smoke risks could reduce residential exposure.

The numbers in context

28,154 respondents from 21 countries. Mean harm perception: 5.2/10. 61% no in-home smoking. Overall OR=1.7. Sweden: OR=3.9. New Zealand: OR=2.3. Significant positive association in all countries.

How the study worked

Cross-sectional analysis of 28,154 adult respondents from 21 countries in the 2021 Global Drug Survey. Logistic regression adjusted for covariates estimated the association between perceived harm of secondhand cannabis smoke exposure and reporting no in-home cannabis smoking in the past 30 days.

What this study cannot tell us

Cross-sectional design cannot prove harm perception causes behavior change; people who do not smoke at home may simply rationalize it as being about harm. Convenience sample of Global Drug Survey respondents may not represent general cannabis users. Self-reported in-home smoking may be subject to social desirability bias.

How to read the evidence

Large multi-country sample with consistent associations, though convenience sampling and cross-sectional design limit causal conclusions.

When this study was published

2024 study using 2021 survey data

The bigger picture

The parallel to tobacco secondhand smoke messaging is clear. Decades of public health campaigns shifted norms around indoor tobacco smoking. This study suggests similar messaging about cannabis could be effective, particularly as legalization removes the stigma that previously kept use out of the home.

Questions still open

Would targeted secondhand cannabis smoke campaigns actually change behavior, or is the association driven by pre-existing attitudes? Do children in homes with cannabis smoking show measurable health effects? How does the association compare to tobacco secondhand smoke perception?

Common questions

Does believing secondhand cannabis smoke is harmful change behavior?

This 21-country study found people who perceive secondhand cannabis smoke as harmful are significantly less likely to smoke cannabis at home, though the study cannot prove the perception causes the behavior change.

How harmful do people think secondhand cannabis smoke is?

The average perceived harm rating was 5.2 out of 10, suggesting moderate concern. However, those with higher concern were 70% more likely to keep cannabis smoking out of their home.

Read the original research

Clearing the air: Heightened perception of harm from secondhand cannabis smoke exposure is associated with no in-home cannabis smoking in a 21-country convenience sample.

Preventive medicine, 189, 108178

View on PubMed ↗Publisher’s paper ↗

Citation

Tripathi, Osika; Parada, Humberto; Liles, Sandy; Shi, Yuyan; Matt, Georg E; Quintana, Penelope J E; Ferris, Jason; Winstock, Adam; Bellettiere, John. (2024). Clearing the air: Heightened perception of harm from secondhand cannabis smoke exposure is associated with no in-home cannabis smoking in a 21-country convenience sample.. Preventive medicine, 189, 108178. https://doi.org/10.1016/j.ypmed.2024.108178