New research indicates store owners could encourage shoppers to forgo plastic bags with a charitable nudge.

Plastic bags start out as fossil fuels then end up in landfills and oceans. Fish and sea turtles eat thousands of tons of plastic every year. That consumption makes its way up the food chain. According to some estimates, people consume about a credit card’s worth of plastic every week.

Ohio State University researchers found that giving customers a 5-cent token toward a charitable donation in exchange for their rejection of a disposable plastic bag reduced plastic bag use by 30%.

The researchers used a behavioral economic theory known as nudging as part of their experiment. According to the theory, nudging can guide people in a certain direction but not restrict their options. The initiative must also be low-cost in order to count as a nudge.

The researchers performed their study at two convenience stores, offering tokens worth a 5-cent donation for one of three charities in exchange for declining a plastic bag, resulting in a decrease in plastic bag use of 30% to 34%.

“The question is the long-term effect. Will it last? I think for all nudges, there is a decay effect because people get used to it in daily life. But would it go completely to zero? I don’t think so,” said Wuyang Hu, co-author of the study and a professor of agricultural, environmental and development economics at Ohio State University. “My prediction is it will reach a steady rate that lasts.”