Washington ? Environmental and energy security goals have a way of clashing.

Federal regulators find themselves under new pressure to better protect Americans from asthma and other lung ailments aggravated by smog. At the same time, President Bush is promoting an energy policy that relies on more smog-producing ethanol.

“This is ethanol’s dirty little secret: It can cause more smog,” said Frank O’Donnell, president of Clean Air Watch, an advocacy group.

Nearly 160 million people now breathe illegal levels of ozone pollution – smog – mostly in and around major cities in California and the East. Scientists with the Environmental Protection Agency will recommend even tougher standards today.

Such a step, they say in a document obtained by The Associated Press, “would provide greater health protection for sensitive groups, including asthmatic children and other people with lung disease, healthy children and older adults – especially those active outdoors, and outdoor workers.”

“The overall body of evidence on ozone health effects clearly calls into question the adequacy of the current standard,” EPA scientists say in their final recommendation to Administrator Stephen Johnson, a Bush appointee.

What the scientists will recommend has stirred controversy within EPA, said a senior government official, speaking on condition of anonymity because he wasn’t authorized to speak about the subject.

EPA staff members have felt they were under pressure from administration officials, including people at the White House, not to give a specific recommendation for tightening the standard, the official said.

Stricter standards could make it even more difficult for states and counties to comply with the Clean Air Act. Billions of dollars might have to be spent on cleaner-burning factories, power plants and cars and more mass transportation.

Bush, in his State of the Union speech last week, urged Americans to reduce gasoline consumption by 20 percent over 10 years by substituting alternative fuels, mainly ethanol. The ethanol would be in gasoline blends of 10 percent to 85 percent.

Smog is produced mainly when tailpipe and smokestack pollutants react with summer heat. Other major sources of the pollution are gas vapors and chemical solvents.

Ethanol, a focus of Bush’s gasoline-reduction plan, helps cut carbon monoxide in winter but can raise smog levels in summer, air pollution experts say. Ethanol releases more nitrogen oxides, a key element of smog, and evaporates more easily than gasoline, adding other air pollutants.

EPA documents show that more ethanol use could raise smog levels about 1 percent, mainly in parts of the Midwest that don’t use cleaner-burning reformulated gasoline.

Bill Wehrum, head of EPA’s air and radiation office, acknowledged that ethanol poses “a possibility of a very small increase” in smog-causing pollutants but said cleaner-burning motor vehicles and 85 percent ethanol blends would minimize it. He said EPA doesn’t view tougher smog limits as being in conflict with Bush’s ethanol goals.

Bush proposes a fivefold boost in the use of ethanol and other alternative fuels.

Stanford University atmospheric scientist Mark Jacobson said that would add 200 deaths a year to the 4,700 now blamed on smog. “It’s a significant concern,” said Jacobson, who believes the worst effects would be around Los Angeles and along the Boston-New York-Washington corridor.