Are climate change perceptions related with plastic policy support? Effects of climate change skepticism, guilt, and efficacy on the acceptance of the plastic tax

PLOS One | https://doi.org/10.1371/journal.pone.0337327 December 29, 2025 11 / 30 We conducted thorough risk assessment demonstrating minimal potential for harm. Survey questions addressed commonly studied psychological constructs without probing sensitive personal experiences, traumatic events, or stigma- tized behaviors. The environmental policy topic represents low-risk subject matter unlikely to cause emotional distress or social vulnerability. Data collection procedures minimized any residual risks through anonymous participation, voluntary response options for all questions, and clear withdrawal procedures accessible throughout survey completion. Our exemption approach aligns with international research ethics frameworks, including U.S. Federal Policy for Protec- tion of Human Subjects (45 CFR 46) categories for exempt research involving anonymous surveys on non- sensitive topics. Similar exemption criteria exist in European and other international contexts for minimal risk social science research. The Korean Bioethics and Safety Act criteria mirror international standards by distinguishing between research requiring full IRB review and minimal risk social science surveys warranting exemption with appropriate safe- guards. Complete exemption documentation was maintained according to Korean regulatory requirements, including detailed protocol descriptions, risk assessments, and participant protection measures, with our research institution’s ethics office confirming exemption appropriateness under applicable regulations.

The demographic characteristics of the respondents were as follows: 772 (49.1%) male and 799 (50.9%) female, with 255 (16.2%) respondents being aged between 19 and 29, 233 (14.8%) aged between 30 and 39, 294 (18.7%) aged between 40 and 49, 314 (20.0%) aged between 50 and 59, and 475 (30.2%) aged 60 and above. In terms of education, 792 (50.1%) had a high school diploma or less, and 779 (49.6%) had a college degree or higher. In terms of income, 1066 (67.9%) earned less than 6 million won, and 505 (32.1%) earned more than 6 million won. Measures and reliability The measurement items and reliability analysis are shown in Table 1, and the reliability test showed that the Cronbach’s α coefficient ranged from 0.635 to 0.891, confirming that the reliability values were all met. All of the questions were measured using a 5-point Likert scale except altruism, and the mean value was used as a variable. Our scale items were carefully selected from established literature with strong psychometric properties. For climate change skepticism, we adopted items from Whitmarsh [87], who developed and validated a comprehensive skepticism scale. This approach aligns with McCright et al’s [102] work in Global Environmental Change measuring public climate skepticism. Our guilt measurement follows Ferguson et al. [90] in Journal of Environmental Psychology, who demon- strated how collective guilt mediates climate change beliefs and mitigation behaviors. Harth et al. [89] similarly validated

guilt measures predicting distinct environmental intentions. For efficacy, we utilized measurements from Bandura’s [93] framework, following Lauren et al.’s [100] application in Journal of Environmental Psychology showing self-efficacy’s importance in environmental behavior. All analyses were conducted using SPSS version 28.0. Descriptive statistics, correlation analyses, and hierarchical multiple regression were performed following established protocols. Moderation analyses employed the PROCESS macro v4.0 [103] with bootstrap confidence intervals (n = 5000). Missing data were handled using listwise deletion (<2% missing cases). Analysis and findings Descriptive analysis To evaluate how the respondents reacted to the plastic tax, we conducted a frequency analysis of the statement, “I sup- port the idea of taxing plastic users more to reduce plastic use.” Fig 1 illustrates the results. With 51.3% in favor of the idea and 13% against it, the plastic tax is found to have a strong positive sentiment among respondents. However, 35.8% of the respondents remained neutral, indicating the potential for attitudinal change.