Aug. 29 — The national air standards for ozone should be revised within the range of 60 parts per billion to 70 ppb, according to a final recommendation prepared by Environmental Protection Agency staff.
The recommendation was included in a 597-page final policy assessment, released Aug. 29, which cites scientific data and exposure information that “provide strong support” for revising the health-based national ambient air quality standard for ozone of 75 ppb. The final policy assessment was prepared by the EPA Office of Air Quality Planning and Standards.
A standard within the range of 60 ppb to 70 ppb “could reasonably be judged to provide an appropriate degree of public health protection, including for at-risk populations and lifestages,” according to the policy assessment.
The final decision on where to set the revised ozone standard now falls to EPA Administrator Gina McCarthy. The EPA is under a court-ordered deadline of Dec. 1 to issue a proposal on whether to retain or revise the existing ozone standard.
A more stringent ozone standard would lead to new emissions control requirements for sources that emit ozone precursors, nitrogen oxides and volatile organic compounds, including power plants, industrial facilities and motor vehicles.
The range identified in the final policy assessment matches the range identified as appropriate by the EPA's Clean Air Scientific Advisory Committee.
In June, the panel of science advisors concluded that there is “adequate scientific evidence” to recommend that the EPA consider setting the ozone standard between 60 ppb and 70 ppb but cautioned that a standard of 70 ppb may not be adequate to protect public health with an adequate margin of safety.
The EPA staff concluded, based on an analysis of controlled human exposure studies, that available data support a level “no higher than” 70 ppb for consideration of the ozone standard. The policy assessment said 70 ppb is “just below” the ozone exposure concentration reported to result in lung function decrements and respiratory symptoms.
The EPA staff also noted that a revised standard of 70 ppb would be “well below” the exposure concentration shown to result in hyperresponsiveness, impaired-host defense capabilities and other potentially adverse respiratory effects.
However, the policy assessment also cited studies demonstrating that potentially adverse lung function decrements and pulmonary inflammation have occurred in healthy adults at an ozone level of 60 ppb. Evidence supports considering an ozone standard “at least” as low as 60 ppb, according to the EPA staff.
The Sierra Club and the American Lung Association both released Aug. 29 statements urging McCarthy to set the standard at 60 ppb, which is at the more stringent end of the range.
Revising the ozone standard to 60 ppb would “certainly do much more” toward meeting the EPA's obligations under the Clean Air Act, according to Janice Nolen, assistant vice president for national policy at the American Lung Association.
Nolen told Bloomberg BNA that while tightening the ozone standard to 70 ppb would be more protective of public health than the current standard of 75 ppb, there is significant evidence supporting a “much more protective” standard.
“This is a scientific question,” Nolen said. “The standard needs to be set where the science drives it.”
The EPA's final policy assessment indicates that days when the ozone level has reached levels below the current standard aren't “healthy” air days, even though they've been labeled as such, Nolen said. She said the standard must be set at a level that is protective of public health, so the public is told “the truth” about the effects ambient ozone levels can have on their health.
Mary Anne Hitt, director of the Sierra Club's Beyond Coal Campaign, also said that available data support a more stringent ozone standard, which she said is needed to protect vulnerable populations.
“Scientists have shown that nothing above 60 ppb level is safe and 70 ppb is far too high if we intend to protect the lungs of young children and senior citizens,” Hitt said in a statement.
Hitt said EPA estimates that setting the ozone standard at 60 ppb would prevent as many as 12,000 premature deaths and 21,000 hospital visits.
While environmental groups urged the EPA to set the ozone standard at the lower end of its identified range, industry groups reiterated their support for the current standard of 75 ppb.
Carlton Carroll, a spokesman for the American Petroleum Institute, told Bloomberg BNA in an Aug. 29 e-mail that the EPA should include the current standard in the range under consideration. He said air quality will continue to improve because states still are working to implement the current standard, which was set in 2008.
“Tightening the standards wouldn't improve air quality faster but would come with enormous costs to jobs and the economy,” Carroll said.
Ross Eisenberg, vice president of energy and resources policy at the National Association of Manufacturers, said in an Aug. 29 statement that the EPA policy assessment “seems to begrudgingly admit” that the current standard of 75 ppb will lead to significant public health benefits over the next few years.
In the assessment, the EPA staff said that populations in urban and non-urban areas can be expected to see “important reductions” in ozone exposure and ozone-induced respiratory problems upon meeting the existing ozone standard.
Eisenberg added that tightening the ozone standard could lead to “the most expensive regulation of all time.” A July economic report commissioned by the National Association of Manufacturers estimated that an ozone standard set at 60 ppb could cost the U.S. economy up to $270 billion per year and lead to the closure of one-third of the coal-fired power plants in the U.S.
Sen. Jim Inhofe (R-Okla.) also released a statement urging the EPA to retain the current ozone standard. He said that the plans supported by environmental lobbyists would “put the entire nation out of attainment and cause any dreams of business expansion to grind to a screeching halt.”
The American Petroleum Institute has estimated that 94 percent of the U.S. population would live in a nonattainment zone if the ozone standard were lowered to 60 ppb.
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The EPA's final policy assessment is available at http://www.epa.gov/ttn/naaqs/standards/ozone/data/20140829pa.pdf.
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