The Clean Air Scientific Advisory Committee (CASAC) wrapped four days of hearings on particulate matter and ozone this week, offering feedback and recommendations as part of its ongoing peer review process for the Environmental Protection Agency’s October 2019 Ozone Policy Assessment, which recommended retaining a key air quality standard from 2015.

This comes as the agency completes its required periodic review and revision of air quality criteria under the Clean Air Act. Agency officials must review six criteria air pollutants, including ozone, under the National Ambient Air Quality Standards.

Career staff in October recommended the EPA’s current ozone pollution standard of 70 parts per billion (ppb) be maintained. Democratic officials and environmental activists have called for further tightening the regulations. 

Regulating ozone is particularly difficult in the West, with a combination of several factors including topography and higher elevations augmenting foreign pollution and other natural factors outside of human-related emissions.

The weeklong hearing reviewed the 926-page draft Policy Assessment, which concluded that “Collectively, these considerations provide the basis for the preliminary conclusion that consideration should be given to retaining the current primary standard of [70 ppb] O3, as the fourth-highest daily maximum 8-hour concentration averaged across three years, without revision.”

“Accordingly, and in light of this conclusion that it is appropriate to consider the current standard to be adequate, we have not identified any potential alternative standards for consideration in this review,” the assessment stated.

Ahead of the CASAC hearing Karen Kerrigan, President and CEO of the Small Business & Entrepreneurship Council, told Western Wire in November that EPA establishing a new standard would exacerbate the challenges that many states, particularly those in the west, already faced with the current 2015 standard.

“Compliance with the 70 ppb standard in itself is going to be very difficult for regions of the country to attain,” she said. “Lowering the standard further would vastly move the goal posts, tie up important infrastructure projects, raise costs and hurt the economy,” she said.

“Hopefully the EPA’s plan to keep the current background ozone standard at 70 ppb will bring some certainty to state and local entities and businesses that are caught in the crosshairs of what is essentially federal zoning,” Kerrigan added.

In preliminary comments, Dr. Tony Cox, CASAC Chair based in Denver, Colorado, suggested that, “For the final PA, it might be useful to add a discussion of the exceptional nature of the current CASAC and NAAQS review process.”

Cox offered several suggestions to “[i]ncrease transparency and logical soundness in deriving conclusions,” along with the PA’s own goals of being “understandable to a broad audience.”

Cox, tapped in 2017 to lead the scientific review board, is an independent expert in qualitative risk analysis. CASAC was formed in 1977 to provide advisory recommendations for the EPA Administrator. Once appointed, the seven-member panel of experts serves a three-year term.

Along with ozone, CASAC reviewed particulate matter and an integrated science assessment for ozone and related photochemical oxidants.

The new standard of 70 ppb was established in 2015.

“The Administrator noted that a revised standard with a level of 70 ppb was estimated to protect the vast majority of children in urban study areas (i.e., about 96% to more than 99% of children in individual areas) from experiencing two or more days with exposures at or above 60 13 ppb (while at moderate or greater exertion),” the PA recalled, referring to former Obama EPA Administrator Gina McCarthy.

While the hearings concluded Friday, public comment is open until December 16.

Colorado Gov. Jared Polis decided earlier this year to change course from his predecessor, fellow Democrat and former Gov. John Hickenlooper, who cited Colorado’s unique challenges in dealing with ozone as the foundation for an EPA waiver for the state’s nonattainment status. Polis, instead, invited EPA oversight, though the state could see federal highway funds cut and invite a tougher permitting process for the state’s industries and manufacturers, as Western Wire reported earlier this year.

Colorado’s Front Range experiences difficulties in addressing elevated ozone levels throughout the year, including temperature inversions in the winter that trap air near the surface. But much of the state’s ozone pollution comes from out-of-state emissions transportation and non-anthropogenic sources, such as seasonal wildfires. Polis’ decision to ignore the waiver process puts the state on the hook for ozone emissions beyond its control, opponents have argued.

Extending the current 70 ppb standard would allow states in the west like Colorado more time to meet nonattainment status.