Reducing single-use plastics (SUPs) milk bottles: a citizen-centric approach to drive impact-driven interventions

This study examined intervention strategies to reduce single-use plastic (SUP) milk bottles through a citizen-centred approach. SUP milk bottles remain underexplored despite their waste impact. Extending the Behaviour Change Wheel (BCW), the research distinguishes between individual-level (i-level) and system-level (s-level) levers. A sequential mixed-methods design was used. Study 1 involved semi-structured interviews with 20 milk drinkers to generate strategies, which were mapped to the BCW and i-level/s-level framework. Study 2 used a Best-Worst Scaling survey (n = 400) to elicit citizen preferences, analysed with a multinomial logit model. Incentives (i-level) were most preferred, followed by regulation & legislation (s-level), while education & information and persuasion & modelling were least favoured. Findings highlight the need for impactful approaches, advancing citizen-informed social marketing and policy design.