We can only do so much: the effect of citizen-targeted interventions to increase plastic packaging waste separation and collection in informal waste systems

Global plastic pollution is increasing dramatically, even in the most optimistic scenarios, with negative impacts on ecosystems and human health. While recovering plastic packaging waste (PPW) is essential, it is constrained by low household separation and the interactions between formal and informal collection systems. Local interventions target citizen behavior, but their system-level effects remain unclear. This study evaluates how citizen behavior and local interventions affect PPW separation, disposal, and formal–informal collection dynamics, identifying the conditions that limit recovery. An agent-based model was developed for Lima, integrating household survey data, waste audits, mass flow analysis, and stakeholder’ interviews. The model simulates citizens’ separation decisions using the COM-B framework, as well as disposal routes, and interactions with formal and informal waste pickers. Results show that collection access interventions increase formal recovery the most, especially in high-income areas (increasing formal collection from 20 ± 2% to 35 ± 3%). Effects in lower-income neighborhoods require more intervention cycles. In these areas, formal collection increases from 10 ± 1% to 25 ± 2%. Simulation also indicates that PPW recovery is mainly constrained by separation rates and disposal patterns, while informal practices limit formal access and sustain recovery from the residual waste stream, with environmental leakage beyond the local scale. Overall, PPW recovery is structurally constrained by separation behavior and formal–informal dynamics, indicating that behavioral interventions alone cannot substantially improve system performance without addressing underlying system conditions.