Effective package warning label systems for communicating relative risks of cigarettes, heated tobacco products, and e-cigarettes: An experimental study with Korean adults

Background: Warning labels are a fundamental public health strategy for communicating about tobacco product risks, but effective warning labels for heated tobacco products (HTPs) and e-cigarettes (ECs) are yet to be determined. We examined the effect of two warning label systems for communicating the relative risks of using cigarettes, HTPs, and ECs. Methods: 1,280 Korean adults were recruited from an online commercial panel, including susceptible non-users of cigarettes, HTPs, or ECs aged 19 to 29 ( n = 444) and current users of these tobacco products aged 19 or older ( n = 836). Participants viewed packages for cigarettes, HTPs, and ECs in a 2 x 2 between-subject experiment: "dashboard " icons integrated into warnings vs. no dashboard; different-sized warnings (70% of cigarette packages, 50% of HTP packs, 30% of EC packages) vs. current equal-sized warnings (50% of cigarette/HTP/EC packages). Results: Participants exposed to the dashboard warning system were more likely than those who were not to report higher perceived harm of cigarettes than ECs, cigarettes than HTPs, and HTPs than ECs, as well as perceived benefit of switching from cigarettes to HTPs, cigarettes to ECs, and HTPs to ECs. Participants exposed to the different-sized warning system did not report differences in perceived relative harm or benefit compared to those who were not, and no interaction of dashboard warnings with warning sizes was found. Conclusion: The use of dashboard icons with texts and colors representing different levels of risk may promote public understanding about the continuum of risk across tobacco products.