5p Plastic Bag Charge

Summary

The 5p bag charge produced one of the most dramatic behavior changes measured in modern environmental policy. A near-trivial cost completely changed the default behavior of millions of shoppers. The UK could study the effect cleanly because Wales, Scotland, and Northern Ireland introduced the charge earlier, providing comparison data for England's later introduction. The result demonstrates the power of price signals even at very low levels to shift habitual behavior when the alternative (bringing a reusable bag) is readily available. The psychological mechanism is partly the payment itself and partly the friction of requesting a bag.

Research question

"Does a 5p charge on single-use plastic bags reduce bag usage in large supermarkets?"

Methodology

Result

Positive

−95% single-use plastic bags distributed by major supermarkets between 2015 and 2021; from 7.6 billion bags/year to <300 million

Evidence strength

Limited

Observational or pre-post design; correlation not necessarily causal.

Replication status

Replicated