Plastic bag bans and fees reduce harmful bag litter on shorelines

Plastic pollution threatens marine and freshwater ecosystems and the services they provide. Although plastic bag bans and taxes are increasingly implemented worldwide, their effectiveness in reducing plastic litter remains unknown. Leveraging the patchwork of bag policies across different geographic scales in the United States and citizen science data on 45,067 shoreline cleanups, we assess the impact of these policies on plastic bag litter. We find that plastic bag policies lead to a 25 to 47% decrease in plastic bags as a share of total items collected at cleanups relative to areas without policies, with taxes possibly further reducing shoreline litter. At a time when many jurisdictions are considering bag policies, while others are preemptively prohibiting them, our study provides evidence that they mitigate shoreline plastic pollution.