The U.S. Environmental Protection Agency (EPA) will revise existing standards for six major air pollutants, according to top agency officials. The changes could yield major public health benefits.

Speaking at a conference Oct. 26, EPA Assistant Administrator for Air and Radiation Gina McCarthy pledged that the agency would review between 2008 and 2011 six major air pollution standards, including one updated late in 2008.

McCarthy emphasized the importance of a multi-pollutant strategy. She said a wholesale review is needed "to actually tell a whole picture, and not individual pollutant-by-pollutant stories," according to BNA news service (subscription required).

McCarthy's comments portend a flurry of rulemaking at EPA. Revising major air pollution standards is a significant undertaking: EPA must collect and distill clinical and epidemiological studies, seek out the advice of air pollution and public health experts, prepare a litany of legal and policy supporting documents, receive intra-administration clearance, and solicit comment from the public and regulated communities.

The complexity of the process is often well worth the effort, according to public health advocates. Clean air standards are among the most beneficial set by government agencies. Even modest improvements in air quality can dramatically reduce adverse health effects such as asthma attacks and heart attacks. Currently, however, the air standards are either out of date or too weak to generate significant new public health gains.

The Clean Air Act names six air pollutants under the National Ambient Air Quality Standards (NAAQS) program: ozone, particulate matter, lead, sulfur dioxide, nitrogen dioxide, and carbon monoxide. For each of the six pollutants, EPA must set standards sufficiently protective of both public health (called the primary standard) and public welfare (called the secondary standard). The Clean Air Act requires EPA to review and, if necessary, revise the standards every five years.

In the past, EPA repeatedly failed to abide by the five-year schedule, sometimes letting a decade or more pass before reviewing a specific pollutant. For example, EPA has not completed a review of the standards for sulfur dioxide since 1996 or for carbon monoxide since 1994. In both of those reviews, EPA chose not to change standards first set in the 1970s. Current reviews for both pollutants are in their early stages.

Early signs indicate the Obama administration will make the NAAQS program a higher priority. Although EPA has not completed a review for nitrogen dioxide since 1996, it proposed revisions to the standards on July 15. The agency is under a court order to set final standards by January 2010.

The new standards would target short-term emission spikes such as those near major highways. "People who live or go to school near these thoroughfares are particularly at risk," according to the American Lung Association (ALA). The ALA is asking EPA to set an even stricter standard for short-term nitrogen dioxide emissions than EPA proposed in July.

Although each of the standards for ozone, particulate matter, and lead has been revised since 2006, the Obama administration will continue to review them, EPA officials say. EPA may find additional revisions necessary because of interference by President Bush's White House.

EPA revised the ozone standards in March 2008. Although EPA tightened both the primary and secondary standards to 0.075 parts per million (ppm) from 0.084 ppm, EPA's scientific advisors had recommended an even lower level. The 2008 revision to the ozone standard was the first since 1997.

EPA had originally sought to set a separate secondary standard tailored to higher ozone exposure levels seen during summer months but was undercut by the White House. During the customary White House review of the rule, conducted by the Office of Information and Regulatory Affairs (OIRA), then-OIRA administrator Susan Dudley asked President George W. Bush to overrule EPA on the secondary standard. Bush agreed with Dudley and forced EPA to abandon its original decision and make the secondary standard the same as the primary standard.

Although ozone is not scheduled for another review until 2013, reviewing the standards ahead of the five-year schedule has been an early priority for current EPA Administrator Lisa Jackson. The agency plans to propose revisions in December. If EPA chooses to lower the standard to the high end of the range proposed by its scientific advisors, 0.070 ppm, it could prevent at least an additional 300 premature deaths and 610 heart attacks annually, according to agency estimates. The proposal is currently under review at OIRA.

OIRA also interfered in EPA's 2006 revision to the air quality standards for fine particulate matter. As in the ozone case, EPA chose to lower the standards, but it ignored the advice of its scientific advisors who had called for an even lower exposure level. OIRA was accused of channeling industry objections into the final rule. The rulemaking docket also shows that OIRA edited the text of the final rule, removing a sentence that said reducing fine particulate matter exposure "may have a substantial impact on the life expectancy of the U.S. population."

Particulate matter is perhaps the most dangerous air pollutant to which humans are regularly exposed. According to BNA news service (subscription required), a recent EPA study found that "1.7 percent to 6.7 percent of all deaths in 2007 in 15 cities were attributable to long-term exposure to fine particulate matter." Lowering the standard "could reduce the risk of mortality from long-term exposure to the pollutant by as much as 89 percent in some urban areas, according to the assessment."

A federal court struck down the 2006 fine particulate matter standards, finding that EPA had not sufficiently justified its decision. EPA expects to propose new standards in July 2010 and finalize them by April 2011.

Lead is the only air quality standard EPA will not formally review during the Obama administration. The current standard for lead was finalized in November 2008. EPA tightened the exposure level to 0.15 μg/m³ (micrograms per cubic meter), from 1.5 μg/m³. The adjustment marked the first time EPA had revised the standard since it was first set in 1978.

However, EPA is in the process of reconsidering the national network of lead pollution monitors. In addition to setting a new lead standard in 2008, EPA announced it would add new pollution monitors to help regulators identify polluted areas. OIRA pressured the agency to double the emissions threshold for determining where monitors should be placed. The change means state and local officials will not be required to place new lead pollution monitors near at least 124 facilities that emit lead. EPA announced July 22 that it would reconsider the threshold.