Vehicles get refueled at a BP gas station. (Julio Cortez/AP Photo)

Environmental Protection Agency Administrator Scott Pruitt on Wednesday expanded the scope of an emergency waiver of Clean Air Act restrictions on motor fuel requirements, saying the waiver would apply not only to Texas but also to 11 states and the District of Columbia through Sept. 15.

The move, prompted by Hurricane Harvey, effectively declares an early end to summer regulations designed to prevent a buildup of ozone pollution, which contributes to lung disease and asthma. The regulations require oil companies to use low-volatility gasoline during the summer months, to prevent gasoline from turning to vapor. However, making summertime-grade gasoline can cost oil refiners several cents a gallon, according to the Energy Information Administration.

Pruitt said in a letter to governors and District Mayor Muriel E. Bowser that companies can now use any blend stock or oxygenate in an effort to speed up gasoline and diesel deliveries to customers in Texas and beyond. Pruitt noted disruptions from refinery closures, pipeline limitations and problems with barge delivery of oil products.

“These supply shortages can be reduced by waiving the requirements to sell low volatility summer” gasoline, his letter said.

The letter eases regulations in Alabama, Georgia, Kentucky, Maryland, Mississippi, North Carolina, South Carolina, Tennessee, Virginia, Louisiana, Florida and the District.

The Renewable Fuels Association hailed the move, saying it would allow broader use of ethanol up to levels as high as 15 percent of motor fuel, the group said. The EPA move “effectively allows for an early end to the summer volatility control season and allows immediate use of winter gasoline in conventional gasoline areas,” Bob Dinneen, president of the RFA said in an email. “This allows for the sale of E15 in those conventional gasoline areas of the states covered by the waiver.”

Dinneen added that “consumers facing likely gasoline supply issues as a result of Hurricane Harvey are one important step closer today to a high octane, low cost alternative.”