The U.S. Environmental Protection Agency’s (EPA) Gasoline Sulfur program sets limits on the sulfur content of gasoline sold in the United States, with the aim of reducing a variety of vehicle emissions. The program relies on tradable credits that allow U.S. refiners and gasoline importers to reach compliance with sulfur specifications. For the second year in a row, in 2023, gasoline suppliers obtained and retired more sulfur credits than they generated, a trend that could increase supplier compliance costs and the price of octane in gasoline if it continues.