By Denis Cuff

MARTINEZ — Oil refineries have sued to overturn a series of new air pollution rules aimed at reducing emissions 20 percent at each of the Bay Area’s five gasoline plants, the largest source of industrial pollution in the region.

The five rules were proposed in the wake of a fire and heavy smoke at the Chevron oil refinery in Richmond in 2012 that sent thousands to hospitals with eye and throat irritation.

The measures, adopted in December and April, aim to tighten pollution controls on cooling and refining towers and other equipment, require more monitoring of pollution at the plant’s borders, and determining if crude oil shipped to the plants is getting dirtier.

Bay Area Air Quality Management District officials said the rules are reasonable measures in a long campaign to reduce refinery pollution.

In two related lawsuits, however, oil refiners argue the rules are part of an unfair and arbitrary strategy without showing whether the costly measures are justified.

“The refinery project is designed to implement the board’s entirely arbitrary and capricious 20 percent emission goal for refinery emissions, without considering whether such significant additional reductions are necessary for the Bay Area to achieve and maintain national and state air quality standards,” lawyers for the oil industry argued in a lawsuit filed last week by the Western States Petroleum Association.

The trade association represents all five Bay Area refineries: Chevron in Richmond, Shell in Martinez, Valero in Benicia, Tesoro north of Concord, and Phillips 66 in Rodeo.

Valero, Tesoro and Phillips 66 filed a separate lawsuit in December. Both were filed in Contra Costa County Superior Court.

Refinery lawyers contend one rule threatens companies’ trade secrets by demanding that each plant report sulfur content and other elements in incoming crude oil so regulators can determine if dirtier crude may be leading to dirtier air emissions.

Oil companies also contend the air district did flawed environmental assessments of the rules by analyzing the rules piecemeal rather than all at once.

Air district managers said they agency is well within its authority to adopt the rules. Their analysis, they say, concluded the rules would have a “negligible” economic impact on profitable refineries.

While the air district set the 20 percent pollution cut as a goal, it based each of the individual rules on reductions that are practical to achieve, said Brian Bunger, the district’s chief counsel.

“The 20 percent is a goal,” Bunger said, “but it’s not a mandate.”

He said the district already routinely uses procedures to protect confidential business information about refinery operations.

If a third party seeks business information about a company, Bunger said, the air district notifies the industry so it can seek a ruling from a judge whether the information is a trade secret.

Andres Soto, a Communities for a Better Environment community organizer, said oil refiners are fighting measures that would reduce pollution related to health problems among refinery neighbors.

“We see this as part of a scorched earth policy of the oil industry to weaken and destroy any regulatory system that affects their profits,” Soto said.

Chevron spokesman Braden Reddall said the air district unfairly singled out oil refineries — and not other industries — for a 20 percent pollution reduction.

“We support the air district when they work to adopt rules based on sound science and protecting public health,” Redall said. “This doesn’t achieve either.”

Air district officials estimate the three first rules adopted in December will reduce total refinery emissions by 14 percent, or 2,310 tons per year of smog-forming gas, small particle pollution, and sulfur dioxide.

That translates into a reduction of less than 1 percent — about 0.6 percent — of the overall 386,316 tons per year of pollution in the nine-county district, officials said. Two additional rules adopted in May are mostly about collecting information to assess whether tighter controls are needed, district officials said.

Contact Denis Cuff at 925-943-8267. Follow him at Twitter.com/deniscuff or facebook.com/denis.cuff.