Psychological outcomes from a citizen science study on microplastics from household clothes washing

Microplastic pollution from synthetic microfibers is an increasing concern to human and ecological health, and household clothes washing is a major contributor to microplastic emissions. Consumer choices and washing behaviors could reduce this pollution, yet the psychological and behavioral drivers of these actions remain unknown and the generalizability of previous findings is unclear. We conducted a pre-registered, three-month citizen science project in which Dutch residents used microfiber-capturing laundry bags at home. Participants completed pre- and post-study surveys to assess psychological factors such as perceived responsibility and specific washing behaviors like load size and washing temperature. Psychological variables relating to environmental concern and engagement were high in the citizen scientists compared to the general population. Awareness and perceived responsibility increased modestly after citizen science participation, but there were no significant changes in identity, personal norms, social norms about sustainability, perceived behavioral control, or intentions to use a laundry bag to capture microfibers. After the study citizen scientists felt less capable of reducing microplastic pollution by using laundry bags. To assess generalizability, we also compared the citizen scientists to a control sample of urban Dutch residents. Consistent with hypotheses, citizen scientists were more likely to be female and highly educated. Key washing behaviors were weakly or uncorrelated with demographics or psychological factors, suggesting that interventions on washing behaviors might focus on specific behaviors and skill development rather than general concern. This pattern also suggests that the differences in demographics between citizen scientists and the general population may be less of a concern for developing interventions than previously suggested. Citizen science is a viable method for studying household washing under real-world conditions and provides insights for designing targeted behavioral interventions.