The Trump administration is expected to announce soon that it will temporarily lift federal smog-cutting restrictions on summer-blend gasoline to curb rising energy prices stemming from the Iran conflict, according to three sources familiar with the matter.

The move would make standard gasoline cheaper by not forcing refiners and retailers to switch to more costly summer blends of gasoline, while also allowing fuel retailers to continue selling gasoline blended with 15% ethanol, known as E15, throughout the summer driving season when stricter rules normally limit its use in much of the country.

The United States normally switches to summer gasoline blends to reduce air pollution by lowering fuel evaporation in warm weather. These blends have lower volatility, measured by Reid Vapor Pressure, to limit evaporating fuel that can contribute to smog.

Oil and gasoline prices have surged as the Iran conflict has disrupted global supply. U.S. crude topped $100 a barrel for the first time since the 2022 Russia-Ukraine shock. U.S. gasoline prices are at the highest levels since late 2023.

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(Reporting by Jarrett Renshaw; editing by Richard Valdmanis and Nick Zieminski)