The Environmental Protection Agency is to decide within weeks whether to reduce the allowable amount of ozone - commonly referred to as smog - in the air.
A tougher standard would require hundreds of counties across the country to find new ways to reduce smog-causing emissions of nitrogen oxides and chemical compounds from tailpipes and smokestacks.
Groups representing manufacturers, automakers, electric utilities, grocers and cement makers met with White House officials recently in a last-ditch effort to keep the health standard unchanged. They argued that tightening it would be costly and harm the economy in areas that will have to find additional air pollution controls.
Oil and chemical companies also have pressed their case for leaving the current requirements alone in meetings on Capitol Hill and with the Bush administration. A dozen senators and the Agriculture Department urged EPA not to tamper with the existing standard.
On the other side are health experts who conclude that tens of millions of people, particularly the elderly and small children, are still being harmed by poor air quality.
EPA said last summer that the current health standard - no more than 80 parts of ozone for every billion parts of air - does not provide needed protection against asthma, heart attacks and respiratory problems.
EPA has estimated a reduction to 70 parts per billion could result annually in 2,300 fewer nonfatal heart attacks; 48,000 fewer respiratory problems, acute bronchitis and asthma attacks; 7,600 fewer respiratory related hospital visits, and 890,000 fewer days when people miss work or school.
Under court order to review the standard, the EPA must decided by mid-March on what to do.
"The less pollution in the air, the fewer people are going to get sick, fewer children will have asthma attacks, fewer people are going to die," says Janice Nolen of the American Lung Association, which has argued along with almost every other health and medical group to tighten the smog standard issued in 1997.
The federal health standards set air quality benchmarks that states and local officials must strive to meet through various pollution reduction measures, or risk federal sanctions such as the loss of federal highway money. The law says the standard must be based on protecting public health and not cost, a position the Supreme Court has reinforced.
EPA Administrator Stephen Johnson has acknowledged the standard should be tightened, but he has been unwilling to go as far as health scientists say is needed to protect older Americans, children and the 20 million people that suffer from asthma.
The EPA's independent science advisory panel recommended a standard of between 60 and 70 parts per billion, as did a second EPA advisory board on children's health.
Both industry lobbyists and environmentalists say they believe Johnson has taken the view that the standard should be tightened to 75 parts per billion - an approach that doesn't satisfy either industry or health experts
"It's a political compromise," says Frank O'Donnell, president of Clean Air Watch, an advocacy group. Even so, he adds, "every major industry is ... putting the squeeze on" to get the White House to leave the current standard in place.
"The results vary but most studies show a steady reduction in the public health burden as the standard is tightened," said Jonathan Levy of the Harvard Center of Risk Analysis.
Levy co-authored a 2006 study that examined the health benefits of tougher smog restrictions in California. It found that tightening the ozone standard to 70 parts per billion would annually result in 270 fewer premature deaths, 280 fewer emergency room visits for asthma and 1,800 fewer hospital admissions for respiratory disease in the state - a reduction of 75 percent in all three categories.
Another study estimated 3,800 premature deaths would be avoided nationwide.
Johnson met shortly before Christmas with representatives from environmental and health groups, including the American Academy of Pediatrics and the American Public Health Association. At the meeting, they echoed the views of 111 health scientists who last year told the EPA the ozone health standards needed to be lowered to between 60 and 70 parts per billion.
Industry groups argue that the science is inconclusive and that the need for a tighter standard has not been shown since 104 counties have yet to meet the current requirements. If the standard is lowered to 75 parts per billion, the number of counties in violation grows to nearly 400, and at 70 parts per billion to 533, according to the EPA.
That means states would be forced to clamp new emission controls on businesses, and motor vehicles to clean up the air.
"It could trigger layoffs nationwide, further eroding U.S. economic competitiveness," Sen. George Voinovich of economically stressed Ohio, and six other Republican senators recently wrote the EPA. More than a dozen senators have weighed in against any change, while 22 House members told the EPA it should abide by "overwhelming scientific evidence in favor of stronger smog standards."
EPA has put the annual cost of meeting a 75 parts per billion standard at $9.8 billion. A 70 parts per billion ozone standard would cost $22 billion annually. But the EPA notes that the costs of either could easily be offset or exceeded by reduced health care costs.
Manufacturing groups from Virginia and Wisconsin have asked their senators to intervene. National lobbying powerhouses such as the National Association of Manufacturers, the American Petroleum Institute, the American Chemistry Council and Alliance for Automobile Manufacturers have met with administration officials and lobbied Congress to keep the smog standard unchanged.
NAM Vice President Keith McCoy said his group told the White House Office of Management and Budget that the EPA was not considering the economic impact.
"Our position is that the existing standard ... should remain in place," said Daniel Riedinger, a spokesman for the Edison Electric Institute which represents investor-owned power companies and recently also took its case to the White House.
"Urge them to retain the current standard," Harry Berry, the county executive/judge in Hardin County, Ky., wrote to his senator, Republican leader Mitch McConnell. Berry warned tougher smog health requirements would be "another blow to the bottom line" for businesses in his area.
William Becker, executive director of the National Association of Clean Air Agencies representing the state and county officials who would have to enforce new air quality requirements, said his group isn't opposed to a tougher standard.
"It's going to make our job that much more daunting," Becker said, "but what trumps that ... is public health."