Gaps between Attitudes and Behavior in the Use of Disposable Plastic Tableware (DPT) and Factors Inﬂuencing Sustainable DPT Consumption: A Study of Hong Kong Undergraduates

: Total waste from human activities, including waste plastics, is huge in Hong Kong. In particular, as a result of the prevention and control measures implemented during the COVID-19 pandemic, take-away meals increased tremendously in Hong Kong, generating disposable plastic tableware (DPT). Although Hong Kong has a charging scheme for plastic bags, it does not have a scheme for plastic tableware. Therefore, this study aimed to understand the attitudes and behavior of people in Hong Kong toward DPT. Our study focused on undergraduate students in Hong Kong, given that they will play a signiﬁcant role in the future of environmental sustainability. The attitudes and behavior of Hong Kong undergraduate students toward DPT were examined through an online survey with 385 respondents. A multiple stepwise regression was conducted to investigate whether cognitive attitude formation factors could explain the sustainable attitudes formed by undergraduate students in Hong Kong. The survey results revealed that most undergraduates considered DPT to be one of the major causes of environmental damage in Hong Kong; however, many of them, particularly those who strongly agreed with this statement, said that the problem of DPT did not affect their quality of life. The regression analysis showed that imposing a DPT charge would be the most signiﬁcant driver to reduce its use. The research ﬁndings identiﬁed gaps between attitudes and behavior regarding the use of DPT and the factors inﬂuencing sustainable DPT consumption.


Introduction
Disposable plastic tableware (DPT) has become a significant environmental issue worldwide due to its negative impact on the environment, including the release of microplastics and their contribution to the global waste problem. In Hong Kong, plastic waste accounts for a significant proportion of municipal solid waste, with plastic tableware alone comprising 266 tons per day in 2020, which represents an increase of about 33% from the previous year [1]. This issue prompted concerns about the sustainability of plastic usage and the potential harm caused by microplastics to both human health and the environment [2,3].
Undergraduate students were identified as a key demographic to target and promote sustainable behavior given their influence on environmental sustainability and the need for them to develop responsible habits for the future [4]. Despite the growing awareness of the environmental impact of disposable plastics, studies on public attitudes and behavior toward their use-particularly among young people-are still limited [5]. This study aims to address gaps through investigating the attitudes and behavior of undergraduate students in Hong Kong toward DPT to inform future policy and promote plastic-free concepts among university students. These findings will also enable other researchers to further examine the topic.
The rest of the paper is organized as follows. Section 2 provides a literature review, including theories and research on DPT, environmental impacts, and public attitudes; the sustainability measures implemented by some developed countries and regions; the current situation in Hong Kong; and our research questions. Section 3 describes the study's research methods. Section 4 presents the descriptive statistics and inferential analyses based on the data collected from the online questionnaires and summarizes the research findings. Section 5 discusses the key conclusions with recommendations for further research. Section 6 concludes the study.

Literature Review and Research Questions
Attitude is a fundamental driver affecting people's behavior. In psychology, an attitude refers to a set of beliefs, emotions, and behavior toward a specific object, person, event, or thing [6]. Attitudes are usually the result of experience or education and can have a powerful influence on behavior. Although a certain attitude is formed toward a specific object and stored in a person's long-term memory, it can change when new information is received [7].

Attitude Formation Process
Attitude formation process can be described using the three-component model of attitude formation, also called the ABC model [8]. The three components are affective, behavioral (conative), and cognitive components. Bakanauskas et al. [6] elaborate on these components as follows: (i) the affective component-the positive or negative reaction to the object of the attitude (i.e., feelings and emotions); (ii) the behavioral (conative) component-the tendency to act on the object related to the attitude (i.e., action and behavior); and (iii) the cognitive component-this involves a person's belief, for example, what we know or think about the object of the attitude (i.e., information and knowledge).
At the cognitive level, a person's attitude is the initial actual evaluation of an object and is influenced based on the individual's internal evaluations (knowledge, experience, and personal preferences) and received information (media information, advertising, and family and friends [6]. These cognition-based factors affect and are inseparable from people's cognitive attitude formation. In the early process of the conceptual model on behavior change, as suggested by Situmorang et al. [9], college students' attitudes toward the environment are affected by preceding factors, such as past experiences and a factual assessment of the subject matter based on their belief and knowledge of nature. Further studies related to the ABC model were previously conducted. Solinger et al. [10] applied the ABC model to perform a conceptual evaluation of another three-component model (TCM) of organizational commitment, which was developed by Allen and Meyer [11]. Further research on the full model was undertaken by Svenningsson et al. [12], who investigated the correlations between the cognitive, affective, and potential behavioral components of attitudes toward technology education in Sweden. In their study on the individual components, Clore and Schnall [13] examined affective attitudes as emergent and embodied evaluative constancy. One of the aims of this study is to explore another component-the cognitive component-and related research questions regarding cognitive formation factors, as exhibited in Section 2.4.
To summarize, cognitive-based attitudes are formed through information received from outside (memory information) and the actions of external factors (external information). The model of the cognitive component of attitude formation, as suggested by Bakanauskas et al. [6], is shown in Figure 1.

Disposable Plastic Tableware, Environmental Impact, and Public Attitudes
Plastic waste, including DPT, is a pressing environmental issue in Hong Kong that is visible and easily retrievable from the environment. An et al. [14] found that the primary sources of microplastics in the environment are wastewater and runoff from urban areas, which can include DPT waste. Given that microplastics have harmful effects on the environment and human health, the impact of DPT cannot be disregarded. Shershneva [15] highlights the need for effective measures to reduce plastic waste both globally and locally

Disposable Plastic Tableware, Environmental Impact, and Public Attitudes
Plastic waste, including DPT, is a pressing environmental issue in Hong Kong that is visible and easily retrievable from the environment. An et al. [14] found that the primary sources of microplastics in the environment are wastewater and runoff from urban areas, which can include DPT waste. Given that microplastics have harmful effects on the environment and human health, the impact of DPT cannot be disregarded. Shershneva [15] highlights the need for effective measures to reduce plastic waste both globally and locally because it is a growing issue in Hong Kong, given the increased use of DPT during the COVID-19 pandemic.
In their survey conducted in Australia, Dilkes-Hoffman et al. [16] found that while respondents perceived plastic waste in the ocean as a significant environmental problem, few acted on this belief by reducing their plastic use, indicating that attitudes toward plastic waste do not always translate into behavioral changes. However, Deng et al. [17] investigated public perceptions and attitudes toward microplastics in Shanghai and discovered that knowledge of microplastics increased people's willingness to act, particularly among women and environmental practitioners.
Miller [18] identified five common misperceptions surrounding the environmental impacts of single-use plastics. The first misperception is that all single-use plastics are non-recyclable; in reality, many can be recycled, and efforts should be made to improve recycling infrastructure. The second misperception is that biodegradable plastics are a sustainable alternative to conventional plastics. However, in reality, many biodegradable plastics do not degrade in natural environments and may even contribute to microplastic pollution. The third misperception is that bans and taxes on single-use plastics are the best solution. In reality, more comprehensive strategies that include product redesign and extended producer responsibility may be more effective. The fourth misperception is that reusable alternatives are always more environmentally friendly than single-use plastics. In their survey conducted in Australia, Dilkes-Hoffman et al. [16] found that while respondents perceived plastic waste in the ocean as a significant environmental problem, few acted on this belief by reducing their plastic use, indicating that attitudes toward plastic waste do not always translate into behavioral changes. However, Deng et al. [17] investigated public perceptions and attitudes toward microplastics in Shanghai and discovered that knowledge of microplastics increased people's willingness to act, particularly among women and environmental practitioners.
Miller [18] identified five common misperceptions surrounding the environmental impacts of single-use plastics. The first misperception is that all single-use plastics are non-recyclable; in reality, many can be recycled, and efforts should be made to improve recycling infrastructure. The second misperception is that biodegradable plastics are a sustainable alternative to conventional plastics. However, in reality, many biodegradable plastics do not degrade in natural environments and may even contribute to microplastic pollution. The third misperception is that bans and taxes on single-use plastics are the best solution. In reality, more comprehensive strategies that include product redesign and extended producer responsibility may be more effective. The fourth misperception is that reusable alternatives are always more environmentally friendly than single-use plastics. In fact, the environmental impact of reusable alternatives depends on factors such as material composition, manufacturing processes, and frequency of use. Finally, the fifth misperception is that single-use plastics are the main driver of marine pollution; however, in reality, other sources, such as fishing gear and land-based waste, also contribute significantly. Therefore, the study by Miller [18] highlights the need for a nuanced and evidence-based approach to addressing the environmental impacts of single-use plastics rather than relying on common misperceptions and oversimplified solutions.

Sustainability Measures of Some Developed Countries and Regions and the Hong Kong Status Quo
The global trend to develop a sustainable environment for future generations places waste reduction at its center. Major economies carried out sustainability measures to ban DPT and implemented relevant policies before 2021. The sustainability measures adopted by some developed countries and regions are summarized below:

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The Canadian government banned several disposable plastics nationwide by the end of 2021, including shopping plastic bags, tableware, straws, and stirring rods [19].

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The European Parliament passed a directive on disposable plastics. By 2021, all European Union member states had to ban disposable plastic products, such as plastic drinking straws, plastic plates, plastic knives and forks, and styrofoam food containers and cups [20].

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The Ministry of Environment of South Korea implemented a stricter restriction on using single-use goods, including takeaway cups in coffee shops and plastic bags in supermarkets. The country aimed to reduce the use of plastic cups by 35% by the end of 2022 [21]. In Hong Kong, the Environmental Protection Department [22] issued a two-month public consultation regarding the implementation of the Scheme on Regulation of Disposable Plastic Tableware in July 2021. It proposed legislation to control DPT in two phases. Phase 1 would involve banning catering premises from providing all types of DPT to customers for dine-in services and providing straws, stirrers, forks, knives, spoons, and plates for takeaway services. In phase 2, takeaway services would be regulated in the same way as dine-in services. Phase 1 of the regulation is expected to be implemented in 2025, and phase 2 will be implemented a few years later, depending on the effectiveness of phase 1 [22].
Previous studies conducted by Greenpeace [23], which is a non-profit organization that exposes global environmental problems and their causes, showed that DPT has decomposed into microplastics in the ocean and pollution spread across Hong Kong. In 2018, a report from Greenpeace [23] found that the average microplastic concentration in Hong Kong waters increased by more than 11 times in the previous three years. In addition, a study in Hong Kong [24] found 129 plastic items in 18 wild mullet samples, and 60% of the wild mullet samples contained plastic items. This finding means that toxins attached to microplastics can enter the food chain through seafood and shellfish and affect human health. Therefore, it is imperative to control DPT when considering local needs and acting in line with the global trend [25].

Research Questions
Many educators believe that social responsibility should be fully integrated into educational modules to help students make social and environmental decisions as entrepreneurs. As the decision makers of the future, undergraduates need to cultivate a vision of sustainable development for the long-term growth of our society. There are currently insufficient research studies on DPT conducted in Hong Kong, especially from the perspective of undergraduate students. The current research takes contemporary university students as the survey objects. Collecting their responses through online questionnaires can help us to understand their attitudes and behavior toward DPT.
The following research questions are addressed in this study: RQ1 What attitudes do undergraduate students have toward DPT? RQ2 What behavior do undergraduate students undertake regarding DPT? RQ3 Do demographic factors affect undergraduate students' attitudes and behavior toward DPT?
RQ4 Could cognitive attitude formation factors explain the sustainable attitudes formed by Hong Kong undergraduates at a cognitive level? Does the cognitive model in Figure 1 work for Hong Kong undergraduates?

Target Respondents and Research Design
The target respondents of this study were undergraduate students who studied at any university in Hong Kong. The students were in different academic years and various academic fields and studied at different local universities; therefore, the sample is representative enough to reflect the views of the entire population on the study topics.
In health and environmental research, individuals' attitudes and behavior are usually assessed through a survey [26]. Therefore, we adopted an online survey method to collect data, while Qualtrics, which is an online survey platform, administered the questionnaire. Social media platforms were used as the main channel. We recruited respondents through sending the questionnaire website link to respondents' social media platforms, such as Facebook, WhatsApp, and instant messaging software via snowball sampling. Before starting the questionnaire, respondents read the information sheet stating the purposes of this study and declared that they were target respondents and agreed to participate voluntarily in the study.
In the quantitative study conducted by Lazcano et al. [27], which studied a large group of young university students in Spain, sampling distribution of proportion (p) was adopted to determine the required sample size. With an acceptable sampling error of 5%, a desirable confidence interval of 95%, and taking a conservative true proportion of p = 0.5, the sample size required was approximately equal to 385. Therefore, our sample size was 385 undergraduate students.

Questionnaire Structure
The questionnaire, which is grounded in the ABC (Affective, Behavioral, and Cognitive components) model of attitude formation [8], was divided into five sections to collect comprehensive information about the respondents and their attitudes toward disposable plastic tableware (DPT) usage:

1.
Socio-demographic questions: This section covered information related to respondents' gender, year of study, and area of study.
Year of study and area of study were also potential cognitive attitude formation factors.

2.
Perceptions and usage of DPT: This section contained questions about respondents' views on the severity of environmental damage caused by DPT in Hong Kong, as well as their habits and frequency of using DPT. This section aimed to capture the cognitive aspect of their attitudes.

3.
Attitudes toward legislative measures: In this section, respondents were asked about their opinions on implementing legislative measures to control the use of DPT in Hong Kong. This section focused on capturing respondents' behavioral intentions and their readiness to act on their attitudes.

4.
Factors influencing feelings and actions: This section explored factors that affected respondents' emotions regarding DPT usage and their actions toward using these items. This section aimed to assess the affective component of their attitudes.

5.
Sustainable behavior and self-assessment: The final section focused on respondents' sustainable behaviors related to DPT usage and included a self-assessment of their attitudes toward reducing DPT usage, integrating all three components of the ABC model.
The questionnaire used various response categories, such as numerical, nominal, or Likert scale options (ranging from 1 to 5, with 1 being "strongly disagree" and 5 being "strongly agree"), depending on the type of question being asked.
To address the four research questions (RQ1-4) outlined in Section 2.4, the collected data were analyzed using descriptive and inferential statistics. Descriptive statistics, including frequency, percentage, and mean, were employed for RQ1-3, while multiple linear regression was used to assess RQ4. The analysis was conducted with consideration for the ABC model, ensuring a comprehensive understanding of the respondents' attitudes and their relationship with behavior. Table 1 reports the descriptive statistics of the 385 survey respondents regarding their gender, year of study, and area of study. Nearly 90% of respondents studied at governmentfunded universities, while the rest studied at Hong Kong's private universities, reflecting the fact that government-funded universities offer most university places. Of the 385 survey respondents, there were slightly more males (51.2%) than females (48.8%). Regarding the distribution of academic years, Years 3 and 4 were the major response groups in this data set, with each group constituting around 30%. Year 5 was the smallest response group (3.6%), reflecting the fact that most Hong Kong undergraduate programs last for four years. The areas of study were business administration (21.8%), social science (20.8%), arts (13.5%), environmental science (11.2%), engineering (11.2%), education (8.1%), and others (13.5%).

Socio-Demographics of Respondents
In short, the socio-demographic variables were relatively balanced in this questionnaire. No significant tendency appeared in gender, the year of study, or the area of study.

Findings on Undergraduates' Attitudes and Behavior
An extremely high percentage (98.7%) of undergraduate students responded with a 4 (agree) and 5 (strongly agree) regarding the seriousness of the current situation of DPT in Hong Kong (Figure 2). In addition, 98.4% of undergraduate students affirmed that DPT will worsen serious environmental damage in Hong Kong. Using a maximum score of 5, the mean scores from the responses to the seriousness of current levels of DPT (4.8) and the environmental damage caused by DPT (4.5) both stand well above 4 ( Table 2), indicating the awareness that these young people have of the environmental harm of DPT.
Regarding the behavior of undergraduates toward DPT, a vast majority of respondents (99%) are in the habit of using DPT in their daily life despite their awareness of its negative environmental impact (Figure 3). .

Min
Max Mean SD Current situation of DPT is serious (from 1 = strongly disagree to 5 = strongly agree) 2 5 4.8 0.44 Environmental damage caused by DPT is serious (from 1 = strongly disagree to 5 = strongly agree) 3 5 4.5 0.53 Regarding the behavior of undergraduates toward DPT, a vast majority of respondents (99%) are in the habit of using DPT in their daily life despite their awareness of its negative environmental impact (Figure 3).         Respondents were then asked how they disposed of unused and used plastic tableware. Figure 4 shows that about 63.3% of undergraduates dispose of unused DPT directly, while only 0.3% put unused DPT pieces in recycle facilities. Figure 5 shows that more than 94.5% of undergraduates directly disposed of used DPT, while only 4.7% clean and save it. Once again, undergraduate students lack sustainable behavior as only 0.8% recycle used DPT. Figure 6 presents further evidence of an attitude-behavior gap toward DPT among undergraduate students, with approximately half using DPT six to nine times per week. This result contradicts what was observed in Figure 2, where 98.7% of students reported being concerned about the problem of DPT as an environmental issue. The mean score of the use of DPT is 7.17 times per week, indicating that, on average, students use DPT at least once per day. ware. Figure 4 shows that about 63.3% of undergraduates dispose of unused DPT d while only 0.3% put unused DPT pieces in recycle facilities. Figure 5 shows that mo 94.5% of undergraduates directly disposed of used DPT, while only 4.7% clean an it. Once again, undergraduate students lack sustainable behavior as only 0.8% used DPT.    94.5% of undergraduates directly disposed of used DPT, while only 4.7% clean an it. Once again, undergraduate students lack sustainable behavior as only 0.8% used DPT.

Differences in Undergraduates' Attitudes and Behavior by Socio-Demographic Variables
Most participants (96.4% of males and 96.8% of females) agreed or strongly agreed with the progressive legislation to ban DPT (Figure 7). A slightly higher percentage of young men (48.2%) than young women (44.7%) strongly agreed with this measure as a means to ensure sustainable environmental behavior. Neither men nor women disagreed with the legislation to ban DPT.

Differences in Undergraduates' Attitudes and Behavior by Socio-Demographic Variables
Most participants (96.4% of males and 96.8% of females) agreed or strongly agreed with the progressive legislation to ban DPT (Figure 7). A slightly higher percentage of young men (48.2%) than young women (44.7%) strongly agreed with this measure as a means to ensure sustainable environmental behavior. Neither men nor women disagreed with the legislation to ban DPT.

Differences in Undergraduates' Attitudes and Behavior by Socio-Demographic Variables
Most participants (96.4% of males and 96.8% of females) agreed or strongly agreed with the progressive legislation to ban DPT (Figure 7). A slightly higher percentage of young men (48.2%) than young women (44.7%) strongly agreed with this measure as a means to ensure sustainable environmental behavior. Neither men nor women disagreed with the legislation to ban DPT. As previously stated, 94.5% of the young people surveyed claim they throw away used DPT. However, students studying environmental science had the lowest throwaway rate at 69.8%, with 30.2% reporting that they clean and keep DPT ( Figure 8). All students studying other subjects disposed of used DPT, except those studying business administration (but even in this subject, 97.6% disposed of used DPT). As previously stated, 94.5% of the young people surveyed claim they throw away used DPT. However, students studying environmental science had the lowest throw-away rate at 69.8%, with 30.2% reporting that they clean and keep DPT ( Figure 8). All students studying other subjects disposed of used DPT, except those studying business administration (but even in this subject, 97.6% disposed of used DPT). Environmental science students have the lowest average usage at 4.49 DPT pieces, while students from other areas of study use roughly seven DPT pieces per meal ( Figure  9). A DPT piece includes a fork, knife, spoon, cup, food container, etc. After observing these differences, it is clear that undergraduates majoring in environmental science are taking more action to reduce their use of DPT compared to other students. Environmental science students have the lowest average usage at 4.49 DPT pieces, while students from other areas of study use roughly seven DPT pieces per meal (Figure 9). A DPT piece includes a fork, knife, spoon, cup, food container, etc. After observing these differences, it is clear that undergraduates majoring in environmental science are taking more action to reduce their use of DPT compared to other students.

Assessing the Influence of Attitude Formation Factors on the Cognitive Component of the Attitude Formation Process Using Multiple Linear Regression
A multiple linear regression using the structure of the cognitive model shown in Figure 1 was adopted to assess how successfully cognitive attitude formation factors (the independent variables) could explain the attitude formed (the dependent variable) based on cognitive aspects using this survey data.
The question "In summary, your attitude toward reducing your use of DPT is:" in the online questionnaire was selected as the dependent variable. As can be seen in Table 3, the responses are diverse, containing both negative and positive responses. It is useful to understand the characteristics of those individuals who gave negative responses and those individuals who gave positive responses. Environmental science students have the lowest average usage at 4.49 DPT piece while students from other areas of study use roughly seven DPT pieces per meal (Figur 9). A DPT piece includes a fork, knife, spoon, cup, food container, etc. After observin these differences, it is clear that undergraduates majoring in environmental science ar taking more action to reduce their use of DPT compared to other students.

Assessing the Influence of Attitude Formation Factors on the Cognitive Component of the Attitude Formation Process Using Multiple Linear Regression
A multiple linear regression using the structure of the cognitive model shown in Fig  ure 1 was adopted to assess how successfully cognitive attitude formation factors (th independent variables) could explain the attitude formed (the dependent variable) base on cognitive aspects using this survey data.
The question "In summary, your attitude toward reducing your use of DPT is:" i the online questionnaire was selected as the dependent variable. As can be seen in Tab 3, the responses are diverse, containing both negative and positive responses. It is usefu to understand the characteristics of those individuals who gave negative responses an those individuals who gave positive responses.  There are two major types of cognitive attitude formation factors in the cognitive model in Figure 1, namely available in memory information and external information. Appropriate questions in the online questionnaire were assigned to each type, and all questions were treated as independent variables.
The questions used as the independent variables in the regression were indexed using the labels shown in the parentheses for easy reference. Appendix A describes these questions in detail.
Questions I1, I2, I3, and E3 were converted to dummy variables of values equal to either 0 or 1. The "following aspects" in E1 and E2 consist of relevant information, past experiences, personal preferences, media information and advertising, family and friends, and other people's behavior.
Using the statistical program SPSS 28, a linear regression with a stepwise method was carried out. The first independent variable with the smallest p-value of less than 0.05 was entered into the regression. The second independent variable with the smallest p-value of less than 0.05 in the remaining independent variable pool was the next variable entered into the regression. If two or more independent variables were in the regression, those with a p-value of more than 0.1 were removed. This process was repeated until there were no more independent variables with p-values of less than 0.05 in the independent variable pool. The final model is shown in Table 4, where the independent variables (i.e., the cognitive attitude formation factors) with their standardized coefficient, t-statistic, and p-value are presented. This model explains 27.3% of the variance of the dependent variable (i.e., the attitude toward reducing the use of DPT). There are two major types of cognitive attitude formation factors in the cognitive model in Figure 1, namely available in memory information and external information. Appropriate questions in the online questionnaire were assigned to each type, and all questions were treated as independent variables.
The questions used as the independent variables in the regression were indexed using the labels shown in the parentheses for easy reference. Appendix A describes these questions in detail.
Questions I1, I2, I3, and E3 were converted to dummy variables of values equal to either 0 or 1. The "following aspects" in E1 and E2 consist of relevant information, past experiences, personal preferences, media information and advertising, family and friends, and other people's behavior.
Using the statistical program SPSS 28, a linear regression with a stepwise method was carried out. The first independent variable with the smallest p-value of less than 0.05 was entered into the regression. The second independent variable with the smallest pvalue of less than 0.05 in the remaining independent variable pool was the next variable entered into the regression. If two or more independent variables were in the regression, those with a p-value of more than 0.1 were removed. This process was repeated until there were no more independent variables with p-values of less than 0.05 in the independent variable pool. The final model is shown in Table 4, where the independent variables (i.e., Based on the results shown in Table 4, the following main conclusions can be drawn: • The cognitive model in Figure 1 was proven to be valid in the online survey data of Hong Kong undergraduate students because the factors from the two types of cognitive attitude formation factors are significant. For example, the most significant factors influencing the model are I1, I3, and I4 from available in memory information and E1 and E2 from external information.

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The four significant cognitive attitude formation factors that are the drivers for positive attitudes toward reducing the use of DPT are as follows: the DPT charge (I4), action for using DPT-relevant information (E2), the problem of DPT seriously affecting your quality of life (I3), and feelings about using DPT-personal preference (E1). The higher the accepted DPT charge or the higher the rating in the other three factors, the more positive the attitude toward reducing the use of DPT.

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The DPT charge (I4) is the most impactful driver with the highest positive standardized coefficient (0.335). This result echoes the HKSAR Government's policy to increase the plastic shopping bag charge from $0.5 to $1.0 per bag, to be effective from January 2023, as suggested by the Council for Sustainable Development (SDC) after conducting a public engagement in 2021 on the control of single-use plastics.
• Two significant cognitive attitude formation factors that are barriers to developing positive attitudes toward reducing the use of DPT are as follows: action for using DPT-media information and advertising (E2), and students in Year 3 or above (I1). • Students in Year 3 or above have a less positive attitude toward reducing the use of DPT compared with students in Years 1 or 2. However, this inertia is not strong because its magnitude (0.118) is less than half the magnitude of the most impactful driver (0.335).

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The higher the rating in action for using DPT-media information and advertising (E2), the more negative the attitude toward reducing the use of DPT. It is the most inhibiting factor, having the highest negative standardized coefficient (−0.222), in fostering a positive attitude at the cognitive level.

Attitude-Behavior Gap
From the analysis of the descriptive statistics on the survey data, we found that undergraduate students are very concerned about the environmental issues caused by using DPT. The majority of respondents (98.7%) acknowledge the seriousness of the problem and nearly 97% of them would support legislation to ban the use of DPT. Despite this fact, around 99% of the respondents routinely used DPT. Each student used on average seven DPT pieces per meal, which is equivalent to 50 DPT pieces per week or nearly 2600 DPT pieces in a year. Moreover, fewer than 1% of undergraduate students put used DPT pieces in recycle facilities. Such a huge quantity of DPT pieces containing microplastics being thrown away significantly aggravates the environmental burden.
One reason that explains this attitude-behavior gap is that for those individuals who gave ratings of 4 or 5 when considering the seriousness of environmental damage caused by DPT (379 respondents), many (293 respondents, see the light yellow area in Table 5) said that this environmental damage does not affect their quality of life (those who gave ratings 1 or 2 in response to "the problem of DPT seriously affects your quality of life"). In addition to there currently being no levy charges on using DPT in Hong Kong, undergraduate students have no determining driver to reduce their use of DPT; therefore, they continue their non-sustainable behavior for convenience. Table 5. Distribution of responses to "the problem of DPT seriously affects your quality of life" and responses to "the seriousness of environmental damage caused by DPT".

Fostering Sustainable Behavior in the City
According to the results, undergraduate students studying environmental science exercise more sustainable behavior toward reducing the use of DPT compared to those individuals studying other subjects. This finding could be attributed to their greater knowledge and expertise in environmental issues. While the local government should organize and plan public education initiatives, environmental science students could also play a significant role in influencing their peers through their environmental knowledge [28]. In addition, it is important to incorporate environmental education into adult learning programs [29]. Smyth et al. [4] to stress that universities have a responsibility to reduce their environmental impact and could uphold this obligation through implementing waste reduction initiatives.
Environmental awareness is crucial for university students as they are one of the major players in shaping environmental policies and social practices. Our research on undergraduate students' attitudes toward the use of DPT is particularly valuable as it sheds light on the current state of environmentally conscious behavior in this group. The findings of our study can inform and guide policymakers, educators, and environmental advocates to develop more effective and targeted strategies to promote sustainable practices and behavior among university students. Through raising environmental awareness and promoting sustainable behavior among university students, we can create a greener and more sustainable future for all.
Besides developing environmental awareness among university students, as highlighted in the cognitive model, charging for DPT is the most effective way to foster positive attitudes toward reducing their use. However, the fast pace of city life and the popularity of low-cost and lightweight plastic packaging made disposable culture prevalent. As a result, a considerable number of undergraduate students have negative attitudes toward reducing the use of DPT. To evolve this culture, banning single-use disposables and increasing the cost of all disposable packaging, while providing environmentally friendly alternatives, is necessary. Another possible solution could be to encourage restaurants to create a friendly environment for customers to bring their own tableware.
The HKSAR Government can also consider improving the recycling facilities for plastic waste. To effectively reduce waste at the source, it is essential to ensure that single-use disposables are properly recycled after use. For instance, the GREEN@COMMUNITY recycling network brand set up by the Environmental Protection Department expanded its network through adding more accessible and convenient collection points, such as tableware recycling bins, in conspicuous places to encourage the public to recycle plastic tableware [30].

Limitations and Future Research
Despite the significant findings of this study, it has several limitations that must be acknowledged. Firstly, the survey sampling method in this study was not simple random sampling in its true form because the target people were not randomly selected and they could choose whether to respond. We adopted a common practice in assuming a sampling distribution of proportion [27] to generate an acceptable sample size of 385 undergraduate students. Therefore, drawing generalized results may not be convincing and further research geared toward producing more holistic conclusions that are reliable and valid is required.
Secondly, like other surveys related to environmental protection, there were nonresponse biases, social desirability biases, and measurement errors. People who responded may have different views from those who did not respond. Self-reported responses may result in respondents under-or over-reporting their attitudes and behaviors toward DPT. Several efforts were made to address these issues, such as the following: (1) steps were taken to ensure anonymity and confidentiality to mitigate non-response bias; (2) exclusion logics were put in place to remove incomplete questionnaires and questionnaires with abnormal responses; and (3) the questionnaire was well distributed to reach all targets, as seen through the fact that these 385 respondents were from different universities and programs with a distribution that reflected the entire population, according to the statistics published by the University Grants Committee of Hong Kong.
Finally, this study did not investigate the impact of social and cultural factors on undergraduate students' attitudes and behaviors toward DPT. For example, in the question "action for using DPT-media information and advertising" (E2), the vast majority of undergraduate students (355) gave a rating from 4 to 5, demonstrating that the respondents' actions were highly to extremely influenced by media information and advertising. However, as shown in Table 4, the attitude of this major group did not occasion a reduction in their use of DPT. This was a strange finding given that the public media and environmental bodies repeatedly promoted strong positive messages on sustainability and environmental protection. These findings could be supplemented by qualitative research, such as selectively inviting some of these respondents to participate in a focus group where a moderator discusses in-depth, open-end questions to further understand how and why the mass media impacts their attitudes. Another future research direction could be to use more established models or theories to further investigate the issue of DPT.

Conclusions
This study sheds light on the attitudes and behavior of undergraduate students toward the use of DPT in Hong Kong. While there is a growing awareness of the negative impact of DPT on the environment and human health, a majority of students still continue to use it frequently, indicating gaps between attitudes and behavior. However, the study also highlights that students majoring in environmental science exhibit more sustainable behavior with regard to using DPT.
Moreover, the study suggests that imposing a charge on DPT could be an effective measure to reduce its use. This finding may provide useful insights for policymakers and stakeholders to develop strategies toward achieving a more sustainable city.
It is essential that every individual takes responsibility for environmental sustainability, and this study serves as a reminder that we must act collectively to address the issue of plastic pollution. Further studies could explore ways to educate and train students to be more environmentally conscious and raise awareness of the detrimental effects of DPT. Overall, the study contributes to understanding the use of DPT and its impact on the environment and human health; therefore, the findings have important implications for promoting sustainability in Hong Kong and beyond.

Conflicts of Interest:
The authors declare no conflict of interest. Table A1. Description of the questions used as the independent variables.

Question
Choice Factor

I1
Year of study