The Environmental Protection Agency is days away from proposing an updated air quality standard that Republicans are sure to target as they try to win concessions from President Barack Obama on his environmental agenda — and industry lobbyists think they have the upper hand.

Under a court-ordered deadline, the EPA must decide whether to put forward a more-stringent national ambient air quality standard, known as NAAQS, for ozone by Dec. 1. The pending decision comes more than three years after Obama announced the agency would withdraw a draft rule it had developed in response to a legal challenge to a version written during the George W. Bush administration. Obama said he didn’t want state and local governments to begin implementing a new standard when the Clean Air Act (PL 101-549) required another ozone review to begin in 2013, but his decision came after months of intense industry lobbying against the rule.

That earlier willingness to reconsider the standard has led some lobbyists to speculate that the president might accept some changes to the standards — namely the deadlines — in the face of GOP efforts to block or delay other aspects of his environmental plans. They especially see room for negotiation on issues such as ozone, because Obama has staked his legacy on action to curb climate change, rather than air pollution in general.

“I think that suggests an openness to consider some of these issues,” said Jeff Holmstead, a former Bush EPA air quality official.

EPA Administrator Gina McCarthy often criticizes the notion that clean air and a healthy economy are mutually exclusive goals, and she maintains that Obama supports the rules her agency puts forward.

“I feel very well supported in everything that I am doing,” she said Monday at a Christian Science Monitor breakfast.

But the White House’s political history with ozone may end up making her job harder this time around.

An Urban Dilemma

Ground-level ozone, formed by the reaction of sunlight, hydrocarbons and nitrogen oxides, is the chief component of smog, the murky haze that famously shrouded the skylines of U.S. cities for decades — and still does in some places.

Several areas around the country still experience more bad smog days than good ones, even though ozone levels have come down across the United States since the EPA began regulating it in 1971. The agency in 2012 designated 227 full and partial counties as being in “nonattainment” with the most recent standard, which dates back to 2008.

Business groups fear a tighter ozone limit will hit the U.S. manufacturing boom at the knees by putting more communities in nonattainment status, thus making it harder to win permits for industrial activities in some locations. A report commissioned by the National Association of Manufacturers warned in July that the rule could become the most expensive regulation on the books if the EPA sets the standard at 60 parts per billion.

Environmental and public health groups say the Obama administration should certainly propose a smog standard much tighter than the 75 ppb level set in 2008. An independent group of scientists charged with evaluating the most recent data on air pollution before the EPA issues rules has already recommended regulators set the next standard somewhere between 60 ppb and 70 ppb, warning that the higher end of that range would likely be inadequate to fully protect public health.

“The American people have a right to know whether the level of ozone in the air is going to make them sick or if there are things they should specifically do to protect themselves,” said Lyndsay Moseley, assistant vice president and director of the American Lung Association’s Healthy Air Campaign.

The EPA under President George W. Bush proposed an ozone standard above the range suggested by the agency’s science advisers — a move Obama’s first EPA administrator, Lisa P. Jackson, said was “not legally defensible” when she decided to reconsider the rule rather than fight environmentalists in court.

Those who back a tighter standard say the science strongly shows that the current smog benchmark does not adequately protect public health. The Clean Air Act prevents the EPA from considering economic costs when setting NAAQS, a concept the Supreme Court affirmed in 2001.

More studies suggest ozone may worsen symptoms associated with cardiovascular diseases and central nervous system disorders, said Janice Nolen, the Lung Association’s assistant vice president for national policy.

“The more we dig into ozone, go beyond the lungs, and look at other aspects of the body, the evidence is increasing that ozone is a far more harmful agent than we previously understood,” she said.

Pushing the Economic Front

One area where opponents of the EPA’s work on ozone could gain traction is by pushing the agency’s science advisers on a Clean Air Act requirement to advise McCarthy on the potential economic costs and energy impacts that could be incurred as state and local governments implement standards — though she’s not allowed to set the standards based on those costs.

“I think that will create an opportunity for congressional oversight and interest,” Homestead said, “the fact that the administrator is supposed to have this information in front of her when she makes this decision.”

But those who support a tighter standard say they expect the president to remain committed to maintaining and strengthening public health protections, regardless of pollutant type.

“In our mind, it is a legacy issue in that it’s important that EPA protect public health with an adequate margin of safety and that the administration follow the science — and on the latter, nobody objects,” said Bill Becker, executive director of the National Association of Clean Air Agencies, which represents state and local air pollution control departments across the country.

McCarthy declined to publicly commit to proposing a stricter ozone standard earlier this week, though she stressed that science, not politics, would drive her decision. But whether politics influences what happens to the standard later on remains to be seen.

“I will not indicate what that decision is, other than to say that it’s going to be based on the science, and I’ll take close consideration of what our scientists have told us and advised us in [the Clean Air Scientific Advisory Committee] and will put a rule out that I think represents that science,” she said. “And it is not a political decision — it is a decision that I have to make.”