Oil refiners must begin removing more sulfur from American gasoline blends, the Environmental Protection Agency (EPA) announced last Monday. But oil industry leaders have taken issue with the EPA’s study used to make the regulation, and say the new requirements may add more to the cost of gasoline than the EPA currently admits, International Business Times reports.

The new rule is a third phase that will cut sulfur content in gasoline from 30 parts per million to 10 parts per million beginning in 2017.

It's a major EPA issue because sulfur burned in gasoline interferes with pollution-control mechanisms in engines and increases emissions linked to a range of respiratory diseases like lung disease and asthma, as well as heart disease and premature births and deaths.

As you might expect, oil companies oppose the new rule and question the methodology by which EPA reached its conclusions.

According to the EPA, the new regulation will raise the cost of gasoline by about two-thirds of 1 cent per gallon and add about $75 to the price of cars. But oil industry officials say the rule will cost their industry $10 billion and increase gasoline costs by up to 9 cents per gallon.

API commissioned a study by Baker & O’Brien, released in June 2013, which found the annual compliance cost for oil refineries will be $2.4 billion, increasing the cost of gasoline by 6 to 9 cents per gallon.

When asked about the EPA’s own estimate for the price increase in gasoline, API spokesman Carlton Carroll said the EPA “is using false assumptions to come up with its cost figure.”

Rep. Lamar Smith (R-Texas), chairman of the Science, Space and Technology Committee, said the EPA is basing the fuel standards on “secret science.”

“A majority of the agency’s claimed benefits for these standards are derived from taxpayer-funded studies that are hidden from the public and cannot be validated by independent scientists,” Smith said in a statement Monday. “Americans impacted by these costly regulations have a right to see the data and determine for themselves if the agency’s actions are based on sound science or a partisan agenda.”

Who's right? We'll have that answer in three years.