The issue of plastic waste generated by tourists has attracted scholarly attention in the early 21st century. Kuniyal et al. (2003) found that during treks in the Indian Himalayan region, 26% of the non-biodegradable waste produced by tourists consisted of plastic waste. The identification of plastic pollution attributed to tourist activities in the Himalayan region has raised significant concerns, given the area’s historical status as being minimally impacted by human intervention. Recent studies on Mount Everest underscored the substantial increase in tourist activity, further exacerbating environmental concerns regarding the plastic waste generated by tourists (Napper et al., 2020; Yang et al., 2021).

Prior investigations into tourist plastic waste have predominantly focused on coastal island destinations, particularly in the Mediterranean and Caribbean Seas (Mankou- Haddadi et al., 2021; Mo et al., 2021; Corbau et al., 2022; Mghili et al., 2022; Portz et al., 2022). Other well-known marine island destinations, such as Jericoacoara National Park in Brazil (Brabo et al., 2022), the beaches of Goa in India (Nigam et al., 2022), Cox’s Bazar Coast in the Bay of Bengal (Rakib et al., 2022), the South China Sea Coast (Dou et al., 2021), Qingdao Beach in China (Pervez and Lai, 2022), Zanzibar (Maione, 2021), and Bali (Smith and Bernal, 2021), have also been studied. Additionally, urban tourist destinations, including municipalities in Spain (Delgado-Antequera et al., 2021), Suzhou (Jin et al., 2022), Guilin (Zhang et al., 2021), and Mar del Plata (Becherucci and Pon, 2014), have received scholarly attention. These studies have systematically explored various aspects of the issue, including the scale, spatial distribution, density, seasonal variations, and types of plastic waste found in these tourist destinations. For instance, Corbau et al. (2022) conducted a comprehensive study in North Sardinia, Italy, which involved collecting 7975 items over 12 months from five pocket beaches, and they identified plastics as the predominant waste type. Smith and Bernal (2021) reported varying waste densities in a Balinese coastal village, ranging from 1.633 items m^-2 at a local tourist attraction (water wall) to 8.389 items m^-2 on the beach at the end of the dry season in September 2018, with plastic food packaging (17.2%) being the most prevalent item. Aragaw et al. (2022) investigated Lake Tana in Ethiopia and found that the onset of the COVID-19 pandemic increased personal protective equipment pollution, with face masks constituting the majority (93.7%) of the observed pollution. In China, Pervez and Lai (2022) observed higher waste density on Qingdao tourist beaches during summer (0.13±0.04 items m^-2) compared to winter (0.04±0.01 items m^-2), with plastics constituting greater percentages in both summer (23.48%) and winter (24.04%) than other litter categories. Zhao et al. (2024) found a significant amount of plastic bottles on the tourism-intensive artificial coastlines of Dongjiang Port in the Binhai New Area, Tianjin, China. However, the characteristics of tourist plastic waste in mountainous destinations are not well understood. The enclosed terrain of these areas often obscures tourist behaviors, and the ecological environment is relatively fragile. Therefore, the behaviors associated with plastic waste in these settings require further study and understanding.

Previous research has predominantly focused on analyzing the spatial distribution characteristics of tourist plastic waste. However, there is a significant lack of studies that examine plastic waste from the perspective of the tourists themselves. Chatterjee and Barbhuiya (2021) investigated the water usage practices of Indian tourists and found that pro-environmental benefits, attitudes, and adherence to social norms were crucial factors influencing their willingness to reduce plastic use. That study identified the innovation of carrying water and the challenge of habit modification as primary obstacles to reducing plastic consumption. Forleo and Romagnoli (2021) explored the perceptions and opinions of the Italian public regarding marine plastic waste, and categorized the respondents into four distinct groups: the silent majority, the least concerned and involved, a small group of letter writers, and the most severe and committed. Lucrezi and Digun-Aweto (2020) examined the willingness of visitors to participate in litter clean-ups at Elegushi Royal Beach, Nigeria, and found a positive correlation between the visitors’ willingness to participate in clean-ups and their previous involvement in such activities, perceived collective responsibility, and the importance placed on policies and investments aimed at reducing litter. Sun et al. (2024) found that hikers’ awareness of consequences, ascription of responsibility, personal norms, environmental knowledge,

connectedness to nature, and pro-environmental behavior in everyday life significantly influenced their intention to engage in littering behavior at Wuyishan National Park in China. Wang et al. (2023b) discovered that higher tourist satisfaction could reduce litter at park sites in China. These studies primarily focused on the behavioral intentions of tourists rather than conducting empirical analyses of their actual plastic usage and waste generation behavior. Given that tourists contribute to plastic waste, understanding their plastic demand and environmental awareness are essential, as they directly affect plastic waste production. Therefore, this study aims to identify the plastic waste generated by tourists based on their observed plastic usage and waste generation behavior.

The term “footprint” was first introduced in environmental research with the concept of the “ecological footprint” in 1992. This concept, developed by Rees and Wackernagel (1996) and later expanded by Wackernagel and Rees (1998), aimed to quantify the ecological impact of human beings and the amount of bio-productive land required to sustain their activities. Over the ensuing decades, this terminology has broadened to include various dimensions such as carbon, nitrogen, water, and energy footprints (Magnani et al., 2007; Hoekstra and Mekonnen, 2012; Martinez et al., 2022). These conceptual frameworks are designed to represent the measurable impacts of human behavior on the ecological environment, and those impacts are often reflected in material emissions and resource consumption. For example, the carbon footprint delineates the direct and indirect greenhouse gas emissions resulting from human activities (Magnani et al., 2007), while the water footprint captures the total virtual water content consumed by all products and services within a specified area (Hoekstra and Mekonnen, 2012).

Existing studies on tourist footprints predominantly focus on the carbon and water dimensions (Luo et al., 2018; Filimonau et al., 2021; Lee et al., 2021). The assessment of tourist footprints is a valuable tool for identifying and predicting the environmental impacts of their activities on tourist destinations. In general, an increase in a tourist footprint increases the risk of environmental pollution and ecological degradation (Filimonau et al., 2021). Reducing tourist footprints and modifying their associated behaviors are effective strategies that tourism managers can use to prevent ecosystem issues and environmental pollution.

In response to the growing concern over plastic pollution, the concept of a plastic footprint has been introduced. However, a universally accepted definition of the plastic footprint is still lacking, and the existing literature has approached this topic from three principal perspectives (Boucher et al., 2019). First, from a usage perspective, the plastic footprint is defined as the quantifiable amount of plastic used within a system, typically expressed in kilograms per year. Second, from an emission standpoint, the plastic footprint is measured as the volume of plastic released into the environment throughout the entire life cycle of a plastic product, including production, transport, use, and end-of-life stages—a phenomenon commonly referred to as plastic leakage. In this context, the plastic footprint is considered an inventory that is measured in mass units representing the extent of plastic leakage into the environment. This comprehensive quantification of resource consumption and the pollutants, including plastic material and its associated toxins, emitted into the environment throughout the life cycle is designated as “the inventory” within the framework of life cycle assessment. Third, the impact perspective assesses the direct and/or indirect effects of emitted pollutants or leaked plastic on human health or the environment. The impact assessment component that is inherent to more sophisticated footprint methodologies requires delineating one or more impact pathways and employing life-cycle impact assessment methodologies. Typically, impact assessment involves the assessment of three key stages: Fate, exposure, and effect. Based on these perspectives, Boucher et al. (2019) have developed and categorized 19 measurement methods into three levels: 1) Business- or product-level footprint methodologies, tailored for the private sector; 2) National- or regional-level footprint methodologies, designed for the public sector; and 3) Individual-level footprint methodologies, intended for citizens and consumers.

The individual-level plastic footprint serves as a pertinent reference for gauging the plastic waste generated by tourists. However, existing methodologies are not suitable for direct application to tourists, as they primarily focus on the plastic waste generated in daily life, which differs significantly from the activities within a tourism context (Holmes et al., 2021). Common tourist activities such as sightseeing, dining out, and staying in hotels are not typically part of daily life (Bessiere and Tibere, 2013; Mitas and Bastiaansen, 2018). During travel, individuals often prioritize convenience and relaxation, potentially leading to reduced pro-environmental awareness and behavior (Miller et al., 2015; Juvan and Dolnicar, 2016; Holmes et al., 2021). Consequently, the characteristics of plastic waste in tourist destinations, including scale, components, and spatiotemporal distribution, may differ from those observed in residential settings. Given the increasing issue of tourism-related plastic pollution, there is a pressing need for a dedicated tool for measuring plastic waste in tourist destinations.

This study used Jabareen’s (2009) conceptual framework analysis to conceptualize plastic footprints. Conceptual framework analysis is a methodological procedure for constructing conceptual frameworks that are applicable to multidisciplinary phenomena, such as sustainable development, and it is grounded in the grounded theory method. This analysis method is widely used in the environmental literature (Jabareen, 2013; Xavier et al., 2017), and it consists of eight distinct phases: 1) Mapping the selected data sources; 2) Conducting an extensive literature survey and categorizing the chosen data; 3) Identifying and naming concepts; 4) Deconstructing and categorizing the concepts; 5) Integrating the identified concepts; 6) Engaging in synthesis, resynthesis, and comprehension; 7) Validating the conceptual framework; and 8) Critically reassessing the framework.

This study systematically conducted a step-by-step analysis in accordance with the conceptual framework. Initially, a comprehensive search was performed on the Web of Science using the keywords “tour*”, “plastic*”, and “waste*”, which yielded 210 articles as of December 19, 2022. The textual and empirical data related to tourist plastic waste were meticulously extracted from this literature, which served as the foundational materials. Subsequently, six primary concepts were identified from the original materials that were collected (Table 1).

In the third phase, the identified concepts were systematically integrated, and their interrelationships were delineated, resulting in the formulation of the initial conceptual framework. The fourth stage involved validating this initial framework through a review by an expert panel that consisted of two experts each from the fields of tourism, psychology and behavioral sciences, geography, ecology, and environmental studies. These experts were asked to meticulously examine and, if necessary, refine the relationships between the various concepts. The fifth step involved a careful examination and confirmation of the semantic clarity of the conceptual framework. Through this iterative process, this study successfully established the final conceptual framework of the tourist plastic footprint (Figure 1).

The term “tourist plastic footprint” refers to the plastic waste generated by tourists through the use of plastic products within a tourist destination. This includes both direct and indirect acquisitions of plastic products. Direct acquisitions involve tourists purchasing products containing plastic directly from businesses. Indirect acquisitions encompass the combination of products and services obtained by tourists that include plastic items, such as disposable toothbrushes provided in hotel services. Tourists may either acquire plastic products within the tourist destination or they may purchase them externally and bring them into the destination. The plastic products obtained by tourists within tourist destinations may become plastic waste, or plastic waste may originate from outside the destination, and both sources contribute to the expansion of the tourist plastic footprint. A tourist's plastic footprint serves as an ecological footprint, and can be used to assess the environmental and ecosystem impacts of plastic generated by tourists. The generation of the tourist plastic footprint may exhibit spatiotemporal dynamics, potentially increasing during specific periods and in particular locations.

In this study, a time-geography approach was employed to quantify the plastic footprint of tourists. The time-geography approach, rooted in the work of Hägerstrand (1989) and further developed by Shaw and Yu (2009), examines individual activities within a spatio-temporal context. It uses individual trajectories to delineate human behavior, and tracks an individual’s movements both spatially and temporally (Hägerstrand, 1989; Ellegård and Svedin, 2012). This methodology is commonly used in environmental studies. For example, it has previously been applied by Ellegård et al. (2016) to estimate the energy consumption associated with the daily activities of individuals, which identified the activities with high energy consumption and their corresponding temporal occurrences.

The movements of tourists within tourist destinations can be conceptualized as continuous spatio-temporal behavior (Gu et al., 2021). Tourists visit various locations at different times, including hotels, scenic areas, and restaurants, thereby creating individual time-space paths associated with plastic-related activities. The acquisition of specific details regarding these individual paths can be facilitated through activity diary surveys (Ellegård et al., 2016; Gu et al., 2021). Based on the existing literature, this study developed a questionnaire to assess the tourist plastic footprint. The initial questionnaire included two sections: 1) Demographic information, including gender, age, education, and monthly income, and 2) Plastic-related information, covering activities, plastic purchases, items and locations, plastic waste generation, and the corresponding items and locations across 24 periods. Activities were categorized into nine distinct types, plastic purchase locations were classified into seven categories, and plastic waste generation locations were divided into ten classifications. A total of 27 plastic item categories were identified by the consensus of five experts in tourism, ecology, and materials science. Preliminary testing was conducted with 30 tourists, and their feedback was used to refine the final questionnaire. Two adjustments were made to the final version: 1) The addition of the activity “rest”, and 2) The modification of “walking” to “walking traffic”. The comprehensive survey contents are detailed in Table 2.

This study selected Fragrant Hills Park in Beijing as the case study location for several reasons. Fragrant Hills is a well-known mountainous tourist destination that attracts a large number of visitors. It provides ample shopping facilities where tourists can purchase plastic products, allowing for the observation of various behaviors related to plastic waste. Located in the northwestern region of Beijing, Fragrant Hills Park spans an area of 188 hectares and reaches a peak elevation of 575 meters above sea level. Visitors typically spend from one-half to a full day exploring the park, while their dining and accommodation needs are generally met outside the boundaries of the scenic area.

Data collection at Fragrant Hills Park was conducted from November 20 to December 15, 2022, using a nonprobabilistic sampling method. Specifically, an accidental or convenience sampling technique was employed, whereby subjects were selected based on their availability and willingness to participate (Atzori et al., 2018). Initial screening questions were used to identify overnight tourists within the target population. Those who expressed interest in participating in the survey provided their contact information via WeChat or email. To minimize disruption to the tourists' plastic-related activities, the questionnaire was sent the following day, and participants were asked to recall their activities and complete the survey before returning it via WeChat or email. Out of 237 tourists approached, 152 agreed to participate, and ultimately, responses were obtained from 103 individuals.

The sample exhibited a slight over-representation of males (50.5%), individuals aged 18-44 years (33.0%), those with a senior high school education (38.8%), and individuals with a monthly income ranging from 1001 to 5000 yuan (33.0%) (Figure 2). Among the 27 types of plastic items considered, tourists reported purchasing 23 types and discarding 26 types. Notably, disposable raincoats were not mentioned by any respondents, likely due to the study area transitioning into the dry season, so no rainy days occurred during the formal investigation.

Descriptive statistical methods were employed to analyze the size and composition characteristics of the plastic footprints of the tourists, using metrics such as average value, standard error, coefficient of variation, extreme value, skewness, and kurtosis. The hierarchical cluster method was applied to categorize the components of the tourist plastic footprints, following the approach outlined by Dudhagara et al. (2016). The between-groups linkage method was used for clustering, with squared Euclidean distance serving as the measure of dissimilarity. The Euclidean distance was calculated as follows:

where d_ij is the Euclidean distance of components i and j; and x_ik is the occurrence frequency of component i in location k; m is the total number of components. All statistical analyses were performed using IBM SPSS 25 software.

The plastic footprint of tourists in Fragrant Hills Park was recorded as 10.04±0.32 items per capita per day (Figure 3a). The observed range extends from a minimum of two items per day to a maximum of 24 items per day. There was only minor variation in the plastic footprints among the tourists, as indicated by a low coefficient of variation (0.324). The overall distribution pattern is relatively uniform, exhibiting positive skewness (0.832±0.238) and kurtosis (0.279±0.472). This indicates that the majority of individual tourists generated plastic footprints below the average value, contributing to the positive skewness observed in the distribution.

The peak values of the tourist plastic footprint were observed during four specific intervals in a day (Figure 3b): 21:00-21:59 (2.45±0.17), 23:00-23:59 (1.72±0.04), 19:00- 19:59 (1.31±0.12), and 12:00-12:59 (1.25±0.12). During other time periods, the plastic footprint per capita remained below one item. Analyzing these periods of elevated plastic footprints along with their corresponding locations revealed that the greater values during 21:00-21:59 and 23:00-23:59 were predominantly generated in hotels. The heightened value recorded during 19:00-19:59 was primarily associated with restaurants outside the scenic area, while the increase during 12:00-12:59 was observed within the scenic area itself.

From a spatial perspective, the tourist plastic footprints were concentrated in hotels, restaurants outside the scenic area, and the scenic area itself (Figure 4). Hotels had the highest incidence, with an average of 4.66±0.19 items per capita per day. The distribution of these plastic items was relatively concentrated, as indicated by a coefficient of variation of 2.276. The main contributors were plastic garbage bags (36.88%), disposable slippers (17.50%), and disposable toothbrushes (13.54%). Restaurants outside the scenic area had a significant plastic footprint of 2.45±0.09 items per capita per day, with a concentrated composition (coefficient of variation=2.247). The predominant components included tableware packaging (39.29%), plastic bags (11.11%), and plastic food boxes (11.11%). In the scenic area, the tourist plastic footprints averaged 2.05±0.14 items per capita per day. The components here also showed relative concentration (coefficient of variation=2.333), with beverage bottles (32.55%) and plastic food packaging (31.60%) being the most common. In other locations, the plastic footprints were recorded at levels below one item per capita per day.

Based on the predominant components of the tourist plastic footprints in each location, these components could be categorized into five distinct categories (Figure 5). The first category includes plastic garbage bags, which are notably abundant in hotels. The second category comprises bathing supplies, disposable toothpaste, toothbrushes, and slippers, which primarily originated from hotels but were present in lower quantities compared to the first category. The third category consists of beverage bottles and plastic food packaging, which were predominantly found in substantial quantities within scenic areas. The fourth category involves tableware packaging, which was prominently produced in restaurants located outside the scenic area. The fifth and final category includes various types of plastic items with smaller proportions that were generated across multiple locations.

The components of the tourist plastic footprints showed a relatively concentrated distribution (coefficient of variation=1.189), with significant contributions from plastic garbage bags (17.12%), food packaging (12.48%), and tableware packaging (9.96%). The per capita quantities of these three types of plastic waste ranged from 1 to 1.718 items per day, indicating that nearly every individual generated these specific types of plastic waste during travel. Notably, the disposal of plastic garbage bags exhibited a distinct time- space concentration, primarily occurring in hotels around 23:00. In contrast, food packaging waste showed a broader distribution across various times and locations (Figure 6). Elevated quantities of food packaging waste were observed during multiple periods throughout the day, particularly between 12:00-12:59 and 19:00-19:59. A significant amount of food packaging waste was generated in scenic areas (51.94%), restaurants outside scenic areas (20.16%), and traffic stations (1.55%).

The average quantity of plastic items acquired by tourists was 11.95±0.31 items per capita per day, which exceeded the plastic footprint, suggesting an overflow of the tourist plastic footprint beyond the study area (Figure 7). A comparison between the composition of the plastic footprints and the types of plastic items purchased at tourist destinations revealed that souvenirs were the primary component of the excess plastic footprint. These souvenirs were purchased by tourists but did not transition into the waste within the confines of the tourist destinations.

Tourist destinations also bear the costs associated with plastic waste originating from external sources. An analysis of the plastic footprint components revealed certain items that were not purchased by tourists within the tourist destination, but were used and subsequently discarded, including masks, fresh-keeping bags, plastic film, and plastic medicine packaging. Although these items constituted only 1.26% of the total footprint, they highlight the need for tourist destinations to manage the burden of plastic waste from external sources.

The locations where tourists procured the plastic products exhibited a relatively concentrated distribution (coefficient of variation=1.052), primarily from hotels (38.91%), groceries within the scenic area (26.40%), and restaurants outside the scenic area (21.28%). The types of plastic items acquired in hotels also showed concentration (coefficient of variation=2.277), predominantly featuring plastic garbage bags (36.95%), disposable slippers (17.54%), and toothbrushes (13.57%). This distribution aligns with the tourist plastic footprints in hotels, suggesting that these plastic items were primarily purchased, used, and discarded within the hotel premises. For groceries within the scenic area, the purchase of plastic products was relatively concentrated (coefficient of variation=2.305), with a predominant focus on beverage bottles (28.31%), plastic food packaging (27.38%), and souvenirs (22.15%). This pattern closely mirrors the plastic footprints left by tourists in the scenic area’s groceries, except for the inclusion of souvenirs. At restaurants outside the scenic area, tourists primarily purchased tableware packaging (38.55%), plastic bags (11.45%), and food boxes (11.45%), which is consistent with the corresponding plastic footprint.

Given the limited research on the contributions of tourists to plastic pollution, this study developed a conceptual framework for understanding and measuring the tourist plastic footprint. The study using empirical data from Fragrant Hills Park in Beijing validated the feasibility of this framework, and indicated that the plastic footprint of tourists in Fragrant Hills Park averages 10.04±0.32 items per capita per day. The primary components of these footprints include plastic garbage bags, food packaging, and tableware packaging. The plastic footprints are concentrated in hotels, restaurants outside scenic areas, and scenic spots.

Hotels have the largest plastic footprint, primarily consisting of plastic garbage bags, disposable slippers, toothbrushes, and bathing supplies, with most of these items disposed of between 21:00-21:59. In restaurants outside the scenic areas, the main components of the plastic footprint are tableware packaging, plastic bags, and food boxes. In the scenic areas, beverage bottles and plastic food packaging are the predominant components.

There is an overflow of the tourist plastic footprint beyond the study area, primarily composed of souvenirs. Tourist destinations also bear the burden of plastic waste from external sources, including face masks, fresh-keeping bags, plastic film, and plastic medicine packaging.

Tourist destinations are increasingly challenged by the issue of plastic waste generated by tourists. However, there is a notable lack of understanding regarding the generation and measurement of the plastic waste from tourists. This study introduces the concept of the tourist plastic footprint, which offers both theoretical and practical contributions to the field of plastic waste management.

This study has three limitations which should be addressed in future research. First, this investigation focused solely on analyzing the tourists' plastic waste over a single day (24 hours) and did not cover the entire travel trip, which could span multiple days. Future research could examine tourist plastic footprints over longer temporal spans. Second, this study did not account for potential variations in the plastic footprints among tourists. Differences in demographic characteristics, levels of environmental awareness, travel behaviors, and motivations may result in variations in the plastic footprints of different types of tourists. Future research could explore these differences and the factors that influence them. Third, this study relied on self-reported activity diaries to analyze the spatio-temporal trajectories of the tourists’ plastic-related activities, which introduces a subjective element. Combining global positioning system (GPS) techniques with self-reported activity diaries could enhance the objectivity of the data on individual paths, thereby providing valuable insights for future studies.