ExxonMobil has agreed to spend $571 million to reduce air emissions at seven U.S. refineries to settle a long-running U.S. Environmental Protection Agency suit for Clean Air Act violations.

The seven plants, located in Baton Rouge, and Chalmette, La.; Baytown and Beaumont, Texas; Billings, Mont.; Joliet, Ill.; and Torrance, Calif., account for 11% of the nation’s oil-refining capacity. All are owned by ExxonMobil except the Chalmette refinery, which is owned by Chalmette Refining LLC, a joint venture between ExxonMobil and Petroleos de Venezuela S.A.

ExxonMobil has begun projects at the sites to add emissions control technologies that collectively will reduce nitrogen oxide by 11,000 tons per year and sulfur dioxide by 42,000 tons per year. Both compounds are linked to respiratory illness. "The emissions reductions required by this settlement will lead to cleaner air and significant environmental and public health benefits," says Acting Assistant Attorney General Kelly Johnson.

Illinois, Montana, and Louisiana joined in the consent decree, which requires ExxonMobil to pay $8.7 million in civil penalties and to finance $9.7 million of supplemental environmental projects. The civil penalties will be split among the three states while the supplemental environmental projects will focus on mitigating other emission sources in the towns surrounding the refineries and on coastal habitat protection and restoration in Louisiana.

ExxonMobil admits no violation of the federal law but claims to welcome the settlement. "We believe [it] is in the best interest of the company and supports the continued trend of emission reductions that has occurred at our refineries," says Premlata Nair, a spokesperson for ExxonMobil. "We strongly support EPA’s reforms and believe these changes will return the program to its original intent."