Interventions to promote household waste segregation: A systematic review.

Waste segregation at source, particularly at the household level, is an integral component of sustainable solid waste management, which is a critical public health issue. Although multiple interventions have been published, often with contradictory findings, few authors have conducted a comprehensive systematic synthesis of the published literature. Therefore, we undertook a systematic review to synthesize all published interventions conducted in any country in the world which targeted household-level waste segregation with or without additional focus on recycling or composting. Following PRISMA guidelines, Web of Science, Medline, Global Health, and Google Scholar were searched using a search strategy created by combining the keywords 'Waste', 'Segregation', and 'Household'. Two-stage blinded screening and consensus-based conflict resolution were done, followed by quality assessment, data extraction, and narrative synthesis. 8555 articles were identified through the database searches and an additional 196 through grey literature and citation searching. After excluding 2229 duplicates and screening title abstracts of 6522 articles, 283 full texts were reviewed, and 78 publications reporting 82 intervention studies were included in the data synthesis. High methodological heterogeneity was seen, excluding the possibility of a meta-analysis. Most (n = 60) of the interventions were conducted in high-income countries. Interventions mainly focused on information provision. However, differences in the content of information communicated and mode of delivery have not been extensively studied. Finally, our review showed that the comparison of informational interventions with provision of incentives and infrastructural modifications needs to be explored in-depth. Future studies should address these gaps and, after conducting sufficient formative research, should aim to design their interventions following the principles of behaviour change.