The U.S. Environmental Protection Agency (EPA) approved a more stringent National Ambient Air Quality Standard (NAAQS) for ground-level ozone (aka "smog"). From the EPA announcement:

EPA today met its requirements of the Clean Air Act by signing the most stringent 8-hour standard ever for ozone, revising the standards for the first time in more than a decade. The agency based the changes on the most recent scientific evidence about the effects of ozone, the primary component of smog.

"America's air is cleaner today than it was a generation ago. By meeting the requirement of the Clean Air Act and strengthening the national standard for ozone, EPA is keeping our clean air progress moving forward," said EPA Administrator Stephen L. Johnson.

The new primary 8-hour standard is 0.075 parts per million (ppm) and the new secondary standard is set at a form and level identical to the primary standard. The previous primary and secondary standards were identical 8-hour standards, set at 0.08 ppm. Because ozone is measured out to three decimal places, the standard effectively became 0.084 ppm: areas with ozone levels as high as 0.084 ppm were considered as meeting the 0.08 ppm standard, because of rounding.

Although the standard is, as EPA noted, the most stringent ozone NAAQS ever adopted, it is not as stringent as that recommended by the EPA's Science Advisory Board. Also of note, EPA Administrator Stephen Johnson stated he wants Congress to give the EPA authority to consider costs when setting NAAQS under the Clean Air Act. The Washington Post reports:

The Environmental Protection Agency yesterday limited the allowable amount of pollution-forming ozone in the air to 75 parts per billion, a level significantly higher than what the agency's scientific advisers had urged for this key component of unhealthy air pollution.

Administrator Stephen L. Johnson also said he would push Congress to rewrite the nearly 37-year-old Clean Air Act to allow regulators to take into consideration the cost and feasibility of controlling pollution when making decisions about air quality, something that is currently prohibited by the law. In 2001, the Supreme Court ruled that the government needed to base the ozone standard strictly on protecting public health, with no regard to cost. . . .

Nearly a year ago, EPA's Clean Air Scientific Advisory Committee reiterated in writing that its members were "unanimous in recommending" that the agency set the standard no higher than 70 parts per billion (ppb) and to consider a limit as low as 60 ppb. EPA's Children's Health Protection Advisory Committee and public health advocates lobbied for the 60-ppb limit because children are more vulnerable to air pollution. . . .

Rogene Henderson, who chairs the agency's Clean Air Scientific Advisory Committee, said in an interview that she disagrees with Johnson's decision even as she welcomed a tighter standard.

"We can't kid ourselves that this is as health protective as we would like, but this is a step in the right direction," Henderson said. "I understand that with our dependence on fossil fuels, it's difficult to reduce ground-level ozone. But the fact that it's difficult doesn't mean it's not worth doing."

A slew of industries had recently urged White House officials to keep the current limit, effectively 84 ppb, to minimize the cost of installing pollution controls. The EPA estimated that it will cost polluting industries $7.6 billion to $8.8 billion a year to meet the 75-ppb standard, but that rule will yield $2 billion to $19 billion in health benefits. . . .

Under the Clean Air Act, the federal government is obligated to reexamine the science underpinning its smog standards every five years. The agency last revised the standards in 1997, and 85 counties have yet to meet those rules.

As both industry and environmentalist groups are unhappy with the new standard, litigation will surely follow.

The Washington Post reports this morning that President Bush overruled EPA plans to have a modestly tighter ozone standard. In particular, the story reports that Bush told the EPA not to set a secondary "public welfare" standard for ozone that was more stringent than the primary "public health" standard.

documents, which were released by the EPA late Wednesday night, provided insight into how White House officials helped shape the new air-quality rules that, by law, are supposed to be decided by the EPA administrator.

The White House Office of Management and Budget (OMB) questioned in a March 6 memo to the EPA why the second standard was needed. EPA officials answered in a letter that high ozone concentrations can cause "adverse effects on agricultural crops, trees in managed and unmanaged forests, and vegetation species growing in natural settings."

The preamble to the new regulations alluded to this tug of war, stating there was a "robust discussion within the Administration of these same strengths and weaknesses" in setting the secondary standard. The preamble went on to say that the decision to make the two ozone limits identical "reflects the view of the Administration as to the most appropriate secondary standard."

The effort to rewrite the language — on the day the agency faced a statutory deadline — forced EPA Administrator Stephen L. Johnson to postpone at the last moment a scheduled news conference to announce the new rules. It finally took place at 6 p.m., five hours later than planned.

Particularly interesting is the Post's report that Solicitor General Paul Clement expressed concerns about the revision.

The president's order prompted a scramble by administration officials to rewrite the regulations to avoid a conflict with past EPA statements on the harm caused by ozone.

Solicitor General Paul D. Clement warned administration officials late Tuesday night that the rules contradicted the EPA's past submissions to the Supreme Court, according to sources familiar with the conversation. As a consequence, administration lawyers hustled to craft new legal justifications for the weakened standard.

The story quotes an environmentalist attorney accusing the White House of "unprecedented and an unlawful act of political interference." This strikes me as quite hyperbolic. Insofar as the relevant Clean Air Act language leaves the EPA Administrator with any policy discretion in the setting of standards — and I believe it does — there is nothing illegal or improper with the President directing the EPA Administrator to exercise that discretion in accordance with administration policy. If the revised standards fail to hold up in court — and I have no opinion on this matter as I have not yet read the relevant documents — it will not be due to any supposedly "unlawful" interference by the President, but because the EPA failed to provide an adequate justification for the new standard.

UPDATE: John Walke of NRDC, the "environmentalist attorney" quoted above, responds in the comments here. He makes a strong case that the EPA set forth a weak justification for the new ozone NAAQS, largely due to last minute instructions from the White House to modify their decision. Assuming Walke's characterization is accurate, the NAAQS standard may well fall in court.

To clarify my position, there is nothing "unprecedented" or "unlawful" about a White House directing an EPA Administrator to exercise his discretion in accordance with Administration policy. Whether it has happened in the context of setting a NAAQS standard or not, it has happened with many EPA decisions over the years. Harping on alleged "interference" makes for a good soundbite, but I think it detracts from the real issue: Whether or not the EPA articulated an adequate justification for its decision under the Clean Air Act. The EPA's rule in this case may well be "unlawful," as Walke argues. If so, it is because of the substance of EPA's justification and its failure to articulate an adequate justification for the rule. Even if this was due to the last-minute nature of the President's interference (a point which Walke makes quite strongly), the fact of Presidential "interference" is not, in itself, either unprecedented or unlawful.