Toxic fumes from cars and gasoline would be cut significantly under new limits on cancer-causing benzene, adopted by the Bush administration under legal pressure from environmental groups.

The requirements, to take effect between 2009 and 2011, would reduce toxic emissions of benzene and other pollutants from passenger vehicles by up to 80 percent in the next two decades, the government said Friday.

The Environmental Protection Agency said the rules would toughen benzene standards for gasoline, require cleaner-starting engines in cold temperatures and tighten fuel container standards to reduce the evaporation of harmful fumes.

"Americans love their cars. By clearing the air of tons of fuel and exhaust pollution, President Bush and EPA are paving the road toward healthier drivers and a cleaner environment," said EPA Administrator Stephen Johnson.

The new rule meets a court order that EPA require refineries to meet an average 0.62 percent benzene fuel limit by 2011, down from the current average of 0.97 percent. The rule also would create a trading program that would let refineries buy emissions credits to meet new regional limits, rather than impose strict emissions controls.

Benzene is a highly toxic pollutant known to cause cancer, and is one of the worst sources of cancer risk in many parts of the country.

While hailing the stricter standards for benzene emissions, some critics attacked the credit-trading program, which they said would let refineries in some parts of the country avoid significant reductions in benzene levels in their gasoline.

"Having benzene levels go down in Newark, New Jersey won't do much for the health of people in Portland, Oregon," said Emily Figdor of U.S. Public Interest Research Group.

She and other critics called it disappointing that EPA would "undermine" its own program by adopting the trading plan.

Pacific Northwest lawmakers have complained that because much of the region's gasoline comes from benzene-rich oil from Alaska, its gasoline has nearly twice as much benzene as the national average.

Sen. Ron Wyden, D-Ore., said the new regulations would bring gasoline sold in Oregon and Washington in line with other parts of the country. The standard for the Northwest would drop from 1.8 percent benzene fuel limit to 0.69 percent by 2011 -- just above the national average.

"Today the EPA acknowledged that folks in the Northwest have the same right to breathe clean air as folks in other parts of the country," Wyden said.

The EPA said it adopted regional standards -- which range from 0.52 percent along the East Coast to 0.9 percent in the Rocky Mountains -- because a single national standard would be difficult and costly to impose.

Benzene levels vary widely from refinery to refinery, and a program that required all refiners to reach the same benzene level at the same time would be extremely expensive for a large number of refineries, said EPA spokesman John Millett.

By setting a national average, the program provides refiners "a degree of flexibility in the amount of benzene reduction they pursue," resulting in an overall reduction in benzene levels while minimizing costs, Millett said.

Frank O'Donnell, president of the Clean Air Watch advocacy group, called the new rule "a positive step" that "suggests that the November elections may be having a positive impact on EPA actions." Wyden and other Democrats are now in a stronger position to challenge the EPA, O'Donnell said.

The new plan would set new evaporative standards for fuel containers, beginning in 2009. It would require, starting in 2010, that passenger vehicles started up at cold temperatures emit fewer pollutants.

And, by 2011, the agency would require that all gasoline, which is now allowed to contain little more than 1 percent benzene, have only 0.62 percent or less benzene.

Congress required EPA to issue mobile source air toxic regulations by 1995. Two environmental groups, represented by environmental law firm Earthjustice, won a court order in 2005 forcing EPA to issue a preliminary proposal last year and a final rule by Friday.

The new standards will cost consumers an estimated $400 million at dealers' lots and other stores, but the extra cost should be less than $1 per vehicle, EPA said.