BACKGROUND: Communicating about the relative risks of e-cigarettes compared to cigarettes is challenging in part due to uncertainties around risks of using e-cigarettes. This experiment assessed how adults who smoke respond to different relative risk information formats.
METHODS: In November 2024, we recruited 1501 Canadian adults who ever smoked from an online consumer panel. Participants were randomized to view a photo of one of four e-cigarette packages with a standard nicotine warning (“Nicotine is highly addictive.”) and contrasting relative-risk information: none (control); “Use of this product is less harmful than smoking”(text-only); a thermometer with an arrow showing a 70% lower risk level (fixed-risk imagery); or thermometer with bracket showing a 50%-90% lower range risk (risk range imagery). Participants rated the relative harm of e-cigarettes versus smoking (recoded: 0=equally/more harmful/"don't know"; 1=less harmful), willingness to try the product presented (recoded: 0="not at all"/ 1="a little" to "extremely"), and motivation to switch completely from cigarettes to e-cigarettes (recoded as: 0=none; 1=any). Logistic models estimated treatment effects (vs. control) and their interactions with current e-cigarette use.
RESULTS: Text-only messages showed no effect versus control. Participants only exposed to fixed-risk imagery were more likely than those in the control group to view e-cigarettes as less harmful than cigarettes (OR=1.40, 95% CI=1.01–1.94, p-value=0.04). Those exposed to risk range imagery reported greater willingness to try (OR=1.58, 95% CI=1.17–2.13, p-value=0.01) and switch to e-cigarettes (OR=1.51, 95% CI=1.12–2.05, p-value=0.01) than those in the control group. Vaping status did not moderate these effects. Results remained consistent after adjusting for demographics and tobacco use variables.
CONCLUSIONS: Pictorial representations of relative risk can influence smokers' perceptions and intentions, whereas text-only descriptions do not. Risk range imagery that captures the uncertainties around e-cigarette risks promoted behavioral intentions. Future research should evaluate how such messages influence behaviors under natural exposure conditions.