Environmental context and socio-economic status drive plastic pollution in Australian cities

Plastic pollution is a critical environmental concern. There is a growing focus on this transboundary issue, and a corresponding increase in public and government awareness. Understanding the key factors associated with litter and mismanaged waste on land will help to predict where and how waste enters the environment, providing opportunities for low cost, effective interventions. There exist only a few large-scale datasets with which such analyses can be conducted. To fill this knowledge gap we analysed a national, designed survey dataset of litter in the environment from Keep Australia Beautiful (2007-2017). We found that debris decreased significantly, with a nearly 6% decrease over the decade. Using generalised additive model modelling of 17 653 surveys at 983 sites around Australia, we found that site type, land use, state, population, and socio-economic status had the strongest relationships (in decreasing order) with litter distribution. Higher levels of litter were found in economically and socially disadvantaged neighbourhoods. Site types related to transitory human use such as highways and carparks, had more litter than areas with higher aesthetic or cultural value such as beaches, parks, and residential neighbourhoods. Sites that were sources of litter, such as shopping centres and retail strips, also had elevated litter counts, as did surveys near waterways. This enhanced understanding of the factors that influence litter deposition will help to craft more effective policy solutions, and can also improve our models of litter loads on land, and subsequent input to the ocean.