Biodegradable and compostable plastic packaging (BCPP) has the potential to reduce a global plastic waste problem. We aimed to identify influences on buying BCPP as a basis for designing strategies that enable BCPP’s environmental benefits. Using a UK-focused citizen science dataset, we thematically analysed 610 survey responses to a question exploring reasons for BCPP purchase. Themes are categorised as barriers and enablers and according to the components of the Capability, Opportunity, Motivation, and Behaviour (COM-B) model of behaviour. Key barriers concerned: psychological capability (not understanding terminology used to label packaging, not taking notice of packaging, and preferring other types of packaging and product qualities); reflective motivation (negative beliefs about BCPP’s environmental impacts and skepticism over decomposition claims), and physical opportunity (no access to appropriate waste management). Key enablers concern: reflective motivation (positive beliefs about BCPP’s environmental impact and resolve to behave pro-environmentally) and physical opportunity (access to appropriate waste management). Reducing ambiguity concerning the labels of biodegradable and compostable may reduce skepticism over environmental claims of packaging. Interventions should improve information about the source of the packaging material, how the packaging waste is processed, and how to dispose of the packaging. This will not be sufficient unless facilities for local BCPP waste collection and processing are increased.

We aim to identify influences on UK citizens’ household food waste recycling as a basis for designing strategies to increase household food waste collection rates via local services. Using a UK dataset (n = 1801) and the COM-B (Capability–Opportunity–Motivation–Behaviour) model as a theoretical framework, we conduct quantitative regression and supporting thematic analyses to investigate influences on citizens’ recycling of food waste. Results show that automatic motivation (e.g., emotions and habit) and psychological capability (e.g., knowledge) predict household food waste recycling. Physical opportunity (i.e., dealing with food waste in other ways such as home-composting or feeding pets/strays, time and financial costs) was the main barrier to recycling food waste identified in thematic analyses. Participants also reported automatic motivation-related barriers such as concerns over pests, odour, hygiene and local authorities’ food waste collection capabilities. Based on findings we recommend the development of clear, consistent communications aimed at creating positive social norms relating to recycling and increasing knowledge of what can and cannot be put in food waste bins. Improved functional design and free distribution of bins and compostable caddy liners developed according to user-centred needs for cleanliness, convenience and hygiene are also needed. These will not be sufficient without a nationally uniform, efficient and reliable system of household food waste collection.

Compostable and biodegradable plastics are growing in popularity but their environmental credentials need to be more fully assessed to determine how they can be a part of the solution to the plastic waste crisis. We present results and analysis on home compostable packaging. This type of packaging requires the citizen to be able to correctly identify the packaging as “home compostable,” to have composting facilities at home, and to successfully compost the plastic. Using a citizen science approach, we engaged with 9,701 UK citizens geographically spread across the UK to examine their capability, opportunity, and motivation to do this. Of this cohort 1,648 citizens performed home compost experiments to test the environmental performance of compostable plastics. We report on the type of plastics they tested and their disintegration under real home composting conditions. The results show that the public are confused about the meaning of the labels of compostable and biodegradable plastics. 14% of sampled plastic packaging items tested were certified “industrial compostable” only and 46% had no compostable certification. Of the biodegradable and compostable plastics tested under different home composting conditions, the majority did not fully disintegrate, including 60% of those that were certified “home compostable.” We conclude that for both of these reasons, home composting is not an effective or environmentally beneficial waste processing method for biodegradable or compostable packaging in the UK.

Compostable plastics have great potential environmental benefits, however, the damage caused by incorrect waste management offsets them. This study aims to develop a behavior change intervention aimed at improving compostable plastic disposal. We illustrate application of the Behaviour Change Wheel framework to design an intervention in this context. First, the target behavior was understood by specifying it and identifying potential behavioral influences. Second, behavioral influences were systematically linked to potential intervention strategies and refined by evaluating the likely affordability, practicability, effectiveness, acceptability, equity and potential for side-effects (APEASE criteria) in a UK implementation context. Finally, intervention content and implementation options were selected by systematically selecting specific Behavior Change Techniques and refining them by evaluating them against APEASE criteria. The target behavior was identified as UK citizens disposing of compostable plastic waste in the food waste bin meant for collection by local authorities. Influences on compostable plastic disposal were identified as “psychological capability” (i.e., attention and knowledge), “reflective motivation” (i.e., beliefs around environmental impact of compostable plastics) and “physical opportunity” (i.e., access to appropriate waste management). “Education” and “environmental restructuring” were the intervention types selected. “Communications/marketing”, “guidelines” and “restructuring the physical and social environment” were the policy options selected. Selected behavior change techniques were: instruction on how to perform the behavior, prompts/cues, adding objects to the environment and restructuring the physical environment. The resulting intervention is a disposal instruction label for compostable packaging, comprising of instructions and a logo. The next step is user testing the developed disposal instruction labels in terms of their effect on promoting the desired disposal behavior. The novelty of this study includes the development of an intervention to reduce compostable plastic waste and the explicit, step-by-step documentation of the intervention development process. The scientific significance is therefore both applied and theoretical. When evaluated, our intervention has the potential to yield insights relating to what improves compostable plastic disposal amongst citizens. This, in turn, has key policy implications for product and package labeling. By openly documenting our method, we demonstrate a systematic and transparent approach to intervention design, providing an adaptable template and model for others.