**1. Introduction**

With shifts in lifestyles and consumption habits, supply chain interruptions, changes in material flows, waste sorting and recycling logistics, falling oil prices, and reduced demand for recycled waste, the COVID-19 outbreak has posed significant challenges for waste management, waste recycling, and the circular economy around the world [1–3]. This waste is not only medical, infectious, and healthcare waste but also general waste such as food waste (FW) and plastic waste (PW).

Within the past decade, food waste and plastic pollution have become key sustainability issues of international concern to policymakers, corporations, local communities, and researchers who are searching for solutions to the resulting environmental impacts across a range of academic disciplines [4–6]. There have been a number of literature review papers on FW and PW issues published in recent years. For example, Muriana [7] assessed the use of mathematical models in food waste and loss, and clarified food waste's dependency on supply chain strategies, while Amicarelli and Bux [8] outlined global approaches, characteristics, limitations, opportunities, and results of food waste measurement methodologies through a systematic and configurative literature review. Bernstad Saraiva Schott et al. [9] reviewed existing life cycle assessment studies on food waste managemen<sup>t</sup> to clarify the

**Citation:** Liu, C.; Bunditsakulchai, P.; Zhuo, Q. Impact of COVID-19 on Food and Plastic Waste Generated by Consumers in Bangkok. *Sustainability* **2021**, *13*, 8988. https://doi.org/ 10.3390/su13168988

Academic Editors: Dimitrios Komilis, Yasuhiko Hotta, Tomohiro Tasaki and Shunsuke Managi

Received: 11 July 2021 Accepted: 6 August 2021 Published: 11 August 2021

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impacts of each treatment method on global warming and decisive factors in setting system boundaries. De Menna et al. [10] systematically reviewed different aspects and approaches for life cycle costing methodologies to evaluate FW managemen<sup>t</sup> and valorisation routes.

The number of review studies on consumer-generated food waste in particular has risen since private households were first identified as key actors in food waste generation in developed economies [11]. For example, Reynolds et al. [12] reviewed literature on FW prevention at the consumption stage. Roodhuyzen et al. [13] developed a framework that conceptualised the generation of consumer food waste in relation to stages of the household supply chain and categorised 116 potential factors of consumer food waste into four groups (behavioural, personal, product, and societal factors). Schanes et al. [14] reviewed the rising number of empirical studies on consumer food waste practices and the factors that foster and impede the generation of food waste at the household level. These studies reveal food waste to be a complex and multi-faceted issue that cannot be attributed to a single variable. Given its complex nature, the growing body of literature sheds light on food-related practices and routines, ranging from planning and shopping, to storing, cooking, eating, and managing uneaten food within the context of food waste generation by adopting practical theories and other conceptual approaches.

With respect to PW studies, Heidbreder et al. [15] provided an overview of the existing social-scientific literature on plastic, ranging from awareness and consumer preference to political and psychological intervention strategies through a review of 187 studies. The review concludes that future studies should further investigate plastic-specific behaviour and implement behaviour-based solutions.

Meanwhile, many FW and PW reduction targets had been set before the onset of this global crisis, including Sustainable Development Goal 12.3 which aims to 'halve per capita global food waste at the retail and consumer levels' by 2030, as well as manage and control waste emissions and reduce marine pollution, with specific reference to targets 12.4, 12.5, and 14.1 [16]. In particular, several countries had issued bans on specific plastic products, optimistic in the hope of reducing serious environmental pollution [17]. For example, the Thai governmen<sup>t</sup> released a 'Plastic Waste Management Road Map' to phase out the use of plastic by 2030 and issued a ban on single-use plastics in January 2020. However, the advent of the COVID-19 pandemic has enhanced the complexities of FW and PW management. Single-use plastic usage is expected to snap back due to growing concerns with hygiene (such as gloves, masks, packaging, etc.) and increased demand for online shopping during the pandemic. However, household food waste generation may abate along with the trends of more conscious food managemen<sup>t</sup> during lockdowns due to fear and anxiety associated with logistic systems amidst concerns about food shortages [2,18,19].

Although there have been a number of studies conducted on the impacts of COVID-19 on household food waste, there has been no research on developing Asian countries or cities, and little is known about the conditions and determinants of consumer food waste during the pandemic. Lockdowns may affect consumer behaviour and attitudes towards FW and PW due to changes in lifestyle habits. It is especially urgen<sup>t</sup> to view this as an opportunity to promote studies that examine the implications of food waste reduction policies in the cities of Asian developing countries where levels of FW and PW are spiking, but where both existing data and the capacity to tackle this issue are limited.

In an earlier study conducted by the authors in 2018 in Bangkok that investigated FW generation trends in Bangkok and the relationship between daily lifestyles and FW [20], it was found that FW issues in Bangkok have quite distinctive features when compared with existing studies (although most are case studies from developed countries). For example, although the proportion of organic waste and FW normally decreases in the context of growing urbanisation, this type of waste has increased in Bangkok since 2015 due to the growth of tourism and changes in food consumption lifestyles. Furthermore, it has been reported that the largest single contribution to FW in developed countries is at the consumption stage (mostly at the household level), while in developing countries, greater food losses occurred at the production and post-harvest stages [21]. However, FW generation in Bangkok is still high compared to developed cities. Moreover, consumers in Thailand eat out frequently and consume ready-made food, which has resulted in the broad distribution of FW throughout the entire supply chain. However, since the advent of the pandemic, people have isolated themselves at home and avoided eating out, giving rise to the research question: What impact, if any, does the pandemic have on behaviour in relation to FW and PW? For these reasons, Bangkok was selected as a case study to investigate the effects of COVID-19 lockdown conditions on household FW, PW, and correlating behaviour. To the authors' best knowledge, this is the first paper to report changes in household FW and PW in Bangkok due to COVID-19 lockdowns and is the only face-to-face questionnaire survey conducted during the outbreak in 2020.

Specifically, the objectives of this study are: (1) to examine the impact of COVID-19 on food and food-related plastic waste generated by consumers, and (2) to evaluate options for preventing and reducing FW and PW even after the crisis to assist the Bangkok Metropolitan Administration (BMA) in implementing medium- to long-term improvements. For this purpose, a cross-sectional questionnaire survey was conducted to capture shifts in respondents' lifestyles during the pandemic, including a focus on behavioural changes in working on-site versus remotely, eating styles, cooking and shopping practices, as well as waste generation before and during the COVID-19 pandemic. Survey results provided insights into policy implications for addressing issues.

Following this introduction, the paper first outlines the state of COVID-19 and FW and PW generation trends in the Bangkok metropolitan area based on existing data in Section 2. The methods employed in the study are presented in Section 2, and results are discussed in Section 3. Section 4 delves further into policy recommendations. Finally, Section 5 outlines the main conclusions and identifies both limitations to the study and recommendations for further research.

### **2. Review of the State of COVID-19 and Food Waste and Plastic Waste Generation** *2.1. COVID-19 in Thailand*

The national governmen<sup>t</sup> published a notice declaring COVID-19 to be a dangerous infectious disease on 29 February, about six weeks after the first case of the virus was found in Thailand on 12 January 2020. An emergency decree and travel ban were issued on 26 March in response to the rising number of cases following a super-spreader event at a boxing stadium on 6 March and additional cases of local transmission. As the number of cases rose, a national curfew was imposed on 3 April, which was lifted in stages in May and June. Of the 3162 cases found between 12 January and 27 June 2020, a total of 3053 people recovered, 51 patients were hospitalised, and 58 deaths were recorded. This survey was conducted between 16 and 19 June, just after the first national curfew was lifted, which means the respondents of this survey had been under lockdown for more than two months. The main timeline of the COVID-19 outbreak in Thailand around this survey is shown in Figure 1.

The Thai governmen<sup>t</sup> instituted a number of preventive measures for COVID-19. The emergency decree on 26 March restricted domestic and international travel, banned entry into and closed high-risk areas, encouraged masks to be worn and promoted hand washing and social distancing. Restaurants and food stalls were allowed to remain open, but only for take-out. The first national curfew that started on 3 April restricted people to their homes between 10 p.m. and 4 a.m.

To curb the rise in infections, the governmen<sup>t</sup> distributed masks, offered subsidies for healthcare services, provided free COVID-19 screenings, subsidised the costs of testing, and instituted programmes to assist persons with disabilities. The governmen<sup>t</sup> also implemented a number of relevant measures to support individuals and companies, including deferrals and exemptions for personal income tax payments, extensions for filing tax returns, and lower taxes for small- and medium-sized enterprises (SMEs) and corporations, as well as subsidies for electricity charges to support people working from home. The subsidy period for compressed natural gas (CNG) was extended for entrepreneurs, and


the withholding tax rate was reduced, while cash subsidies were offered for employees at SMEs and value-added tax (VAT) refunds were expedited.

**Figure 1.** Timeline of COVID-19 outbreak in Thailand.

### *2.2. Review of Food Waste and Plastic Waste Generation in Bangkok*

Based on the data collected in the authors' previous study [20] and officially reported data by the BMA's Department of Environment, time-series changes in FW, PW, and municipal solid waste (MSW) generation between 2003 and 2020 in Bangkok are shown in Figure 2. MSW is solid waste generated by municipal activities (including by residences, supermarkets, retail shops, businesses, service providers, marketplaces, and institutions) that is collected and treated by BMA. The amount of MSW generated fell by about 1000 tonnes per day in early 2020 after the COVID-19 outbreak due to the closure of hotels and restaurants, following a steady increase in the decade prior to the pandemic. Food waste accounts for 50–60% and plastic waste for 20–30% of the total MSW, but COVID-19 has prompted a reduction in food waste and an increase in plastic waste at the city level. Food waste contains unavoidable items such as peels, stems, and bones, as well as leftovers and other avoidable items, but excludes surplus food from the commercial sector and reused and recycled food such as animal feed, which increased rapidly in the late 2010s, mainly due to growing tourism and lifestyle changes. Since the COVID-19 outbreak and the resulting lockdowns, the total weight of MSW has fallen significantly due to a significant reduction in food waste from hotels and restaurants. On the other hand, the amount of plastic waste generated rose and fell along a gentle curve before the COVID-19 outbreak, averaging 2115 tonnes per day in 2019, but increased sharply by 62% in 2020, reaching an average of 3432 tonnes per day between January and April. In addition, contaminated plastic items from food delivery services, such as takeaway bags, containers, bottles, and cups, that are difficult to reuse and recycle comprised more than 80% of MSW in 2020.

**Figure 2.** Food waste, plastic waste, and municipal solid waste generated in the Bangkok metropolitan area. Note: Data on PW and MSW generation in 2020 are the average between January and April 2020 as reported by the BMA's Department of Environment to BBC Thai. No data on food waste generation are available in 2019 and 2020.

### **3. Materials and Methods**

### *3.1. Sampling Size and Analytical Approach*

An extensive face-to-face questionnaire survey of residents in the Bangkok metropolitan area conducted between 16 and 19 June 2020 (just after the first national curfew was lifted) presented a snapshot of changes in respondents' lifestyles during the COVID-19 pandemic. This study applied the calculation formula developed by Yamane [22] to determine sample sizes. Considering the budget and labour required to conduct the survey, the confidence level was set at 93% (or at a precision level of ±7%); accordingly, the appropriate sample size was 222. In this survey, passers-by were randomly sampled on the streets [23] of the Bangkok metropolitan area. The questionnaire included queries about working days, eating habits, and purchasing routes for food both before and after the preliminary outbreak of COVID-19 in January 2020, and responses were expected to reflect the ways in which food and plastic waste has been generated by consumers. Statistical tests (*t*-test, Kruskal–Wallis test, and Dunn's multiple comparisons test) were used to detect behavioural differences before and during the preliminary outbreak. Food delivery services were also evaluated as a potential key component in the COVID-19 success story. Related environmental impacts on food waste, plastic waste, and other problems caused by new food consumption paradigms were also discussed and statistically tested.

### *3.2. Content of Questionnaire*

The questionnaire survey (see Supplementary Material) for consumers on food waste mainly consisted of four sections and covered a range of daily activities. The first section included questions designed to elicit basic information about the respondents, such as gender, age, occupation, educational level, and household income, as well as working days in the office prior to and during the pandemic. The second section posed questions about changes in respondents' food-related habits in their daily routines, including purchasing, cooking, eating, and disposal. The third section highlighted trends in the food delivery service sector prior to and during the pandemic, including primary reasons cited by respondents for the use of food delivery services, main factors considered when selecting specific food delivery services from several alternatives, and frequency of ordering different types of food (Thai, Chinese/Japanese/Korean or western cuisine, fast food, street food, desserts, and beverages) using online food services prior to and during the pandemic. The

fourth section focused on behavioural changes in relation to the generation of household waste, as well as the respondents' attitudes towards and intentions in reducing food waste.

### **4. Results and Discussion**
