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One application of plastics that grew during the COVID-19 pandemic is for social distancing plastic shields, or protective barriers, made from polymethyl methacrylate (PMMA) such as transparent face guards. Although available for other applications, end-of-life impacts for barriers are currently lacking in the literature, and there is a need to fill in this gap to guide decisions. This study evaluated the end-of-life environmental impacts of PMMA barriers in the United States by using life cycle assessment. We evaluated five strategies including landfilling, waste-to-energy, mechanical recycling, chemical recycling and reuse. Data were sourced from literature and various life cycle inventory databases. The Tool for Reduction and Assessment of Chemicals and Other Environmental Impacts (TRACI) was used as the life cycle impact assessment method. Landfilling exhibited the highest impact in all indicators and reuse demonstrated optimal results for global warming potential. A scenario analysis was conducted to explore a combination of strategies, revealing that the most promising approach involved a mix of 40% reuse, 20% mechanical recycling and 40% chemical recycling. Circular economy recommendations are proposed for managing these sources of plastic waste in the United States.

 

Amid the growth of circular economy research, policy, and practice, there are increasingly loud calls for a unified and singular definition of circularity. This unity is needed, proponents argue, to enable swift action in the face of climate and environmental crises. Our work interrogates the ideal of convergence around the circular economy. We ask whether circularity must be singular and uniform in order to be effective. Based on convergence science research and social theory rooted in ideas of divergence, our paper draws on observations of a convergence science workshop, focus groups, interviews, and questionnaires with US-based circular economy professionals to explore shared and divergent understandings and practices of circularity. We find that even among a relatively homogeneous group of research participants (in terms of race, class, and education), there is significant divergence in terms of both practices and perceptions of circular economy principles. We focus in this paper on how research participants understand innovation in the circular economy as just one potential illustration of divergent circularity. Our research contributes to an understanding of circular economy knowledge politics, illuminating how circularity is contested even among those who advocate most strongly for its implementation. We ultimately find opportunity and promise precisely in the spaces of contestation, and see divergence as a way to hold space for multiple ways of being and relating to economies, materials, and beings. These more inclusive pathways, we argue, may be necessary to ensure just and effective transitions to more circular economic forms. 

Buildings account for the largest share of accumulated materials and waste globally. Tracking the material composition, quantity and location of these materials, known as building material stock analysis (MSA), is a first step in enabling the reuse or repurposing of materials, key strategies of the circular economy. While the number of building MSAs is growing, there is a need to coalesce methods, data and scope. Therefore, in this work, we reviewed and evaluated 62 journal and conference articles on MSA of buildings from different angles including scope, boundaries, archetype classification, material intensity determination, approaches (i.e. bottom-up, top-down, remote sensing) and quantity of materials to identify barriers, gaps and opportunities in this area along with its implications for decision-making, policy and regulations. We cataloged the three major approaches of MSAs and discuss their advantages and shortcomings. We also created a comprehensive directory of building archetypes, references and materials for future researchers. As expected, most of the studies estimated that concrete had the largest mass compared with other materials; however, mass-based distribution of materials showed significant variations in different building stocks across the world. Also, embedded plastics and their types remain under-represented in current studies. A major barrier to MSA is related to a lack of information on physical attributes and geographic information system, design and construction data. Policy makers can play a role in mitigating data barriers through instituting regulations that enforce the reporting of building-related data during the permitting process. Furthermore, outcomes of building MSA can help policy makers when considering incentives for design and construction that utilize these abundant building materials.