WASHINGTON — Four companies -- Valero, Sunoco, Tesoro and Suncor Energy -- will install nearly $1 billion in new pollution controls at 18 oil refineries in settlements with the government and seven states over alleged violations of clean air laws.

Valero and Sunoco, responsible for most of the improvements, also will pay fines totaling $8.5 million. The refineries covered in consent decrees filed Thursday in federal courts in Texas and Pennsylvania represent about 15 percent of the nation's refining capacity.

Valero, based in San Antonio, estimates it will cost more than $700 million to install smokestack scrubbers and chemical additives at 13 refineries in six states. That includes $5 million to $6 million that Suncor Energy of Calgary, Alberta, will spend on a former Valero refinery in Denver, Valero spokeswoman Mary Rose Brown said. Tesoro, also based in San Antonio, will spend an unspecified amount to clean up a former Valero refinery in Martinez, Calif.

"We really do believe we are in compliance with the Clean Air Act. Most of these infractions occurred before Valero ever owned or operated these facilities," Brown said.

Once all that work is completed within a decade, emissions of smog-forming nitrogen oxides are expected to drop by 4,000 tons a year and acid rain-causing sulfur dioxide by 16,000 tons, the Environmental Protection Agency said.

Sunoco, based in Philadelphia, will install $285 million in new controls at four refineries in three states to cut their annual emissions of nitrogen oxides by 4,500 tons and sulfur dioxide by 19,500 tons. Both pollutants also cause serious respiratory ailments and worsen cases of childhood asthma.

Valero also will pay a $5.5 million civil penalty and spend an added $5.5 million on environmental projects. Sunoco will pay a $3 million civil penalty and spend $3.9 million on projects.

The settlements are the 14th and 15th reached since December 2000, the last full month of Bill Clinton's presidency, that resulted from EPA investigations into refineries' air quality starting in the mid-1990s.

They are intended to enforce the Clean Air Act, including the 1977 amendments known as "new source review." That program was designed to force industrial sources of pollution to install state-of-the-art emission controls when they make significant repairs or modifications.

"Sixty-five percent of our nation's petroleum refining capacity now has committed to make significant improvements that will benefit everyone," Thomas V. Skinner, EPA's acting enforcement chief, said Thursday.

Kelly A. Johnson, an acting assistant attorney general, said the Justice Department "will continue to aggressively pursue actions like these" across the refining industry.

EPA's inspector general, however, said in a report last year that the agency is doing a poor job of managing the documents that companies submit as part of agreements. Environmentalists also have complained that deadlines in prior settlements were repeatedly extended.

Valero's affected refineries are in Benicia and Wilmington, Calif.; Corpus Christi (two refineries), Houston, Sunray, Texas City and Three Rivers, Texas; Krotz Springs and St. Charles Parish, La.; Ardmore, Okla; and Paulsboro, N.J.

Sunoco's affected refineries are in Philadelphia and Marcus Hook, Pa.; Toledo, Ohio; and Tulsa, Okla.

Source: Associated Press