The EU has taken decisive actions to reduce plastic pollution, including the adoption of the Single-Use Plastics Directive (SUP). However, the implementation of the SUP Directive faces a major challenge: monitoring and enforcement. Uneven surveillance, limited data and cross-border circulation hinder the Directive’s full effectiveness.Citizen generated data has proven to be a key complement to official monitoring, providing broad spatial coverage, cost-effective data collection, and rapid reporting. This policy brief has been produced as part of T4.5 within the more4nature project. more4nature is a Horizon Europe research and innovation project that aims to trigger transformative change in environmental protection by strengthening the role of citizens and communities in environmental governance. The project focuses on enabling citizens to contribute meaningfully to collaborative environmental compliance assurance (ECA) in the areas of zero pollution, biodiversity protection, and deforestation prevention. The goal of the policy brief is to strategically engage policymakers and national agencies, enabling them to act beyond individual “change agents” within their institutions and to bring about more systemic policy and regulatory change. T4.5 has therefore been tasked with producing targeted policy briefs that resonate with global, EU, and national policy processes unfolding during the lifetime of the project. Read this document to discover more about the policy context within the more4nature project. Or take a look at other more4nature policy briefs: Deforestation policy brief Water quality policy brief Pollinators policy brief