The US Environmental Protection Agency's possible reduction in allowable ground level ozone concentrations to 60 parts per billion potentially could trigger sanctions against states that fail to meet them without adequately considering naturally occurring sources, witnesses told a US House Science, Space, and Technology Committee subcommittee.
"Surprisingly high ozone values have been measured at rural monitors in Utah and even within national parks," Amanda Smith, executive director of Utah's Department of Environmental Quality, said in a June 12 hearing before the Environment Subcommittee. "Similar high values have been seen throughout the Intermountain West."
Ground level ozone, or smog, reduction efforts nationally since the 1970s have focused on California and the eastern US, she said in her written statement. "Only recently, as ozone standards have become more stringent, has attention been given to background ozone in the Intermountain West," Smith said.
"Wildfires and stratospheric ozone intrusions also contribute significantly to background ozone levels, and have a disproportionate impact on the Intermountain West," she continued. "It is critical to recognize that the primary causes of high background ozone are beyond the control of the states."
Samuel Oltmans, a senior research associate at the University of Colorado's Cooperative Institute for Research in the Environmental Sciences, said a 2012 study led by Meiyun Lin at the Geophysical Fluid Dynamics Laboratory (GFDL) and Princeton University found background ozone contributes an average 40 ppb to measure ozone in the region during the spring and summer when measured amounts exceed 60 ppb.
"A significant portion of the time, background ozone exceeds 50 ppb under high measured ozone conditions," he added.
'Very difficult'
With such relatively high background ozone contributions, a standard should be at a level which allows regulatory controls to succeed, Oltmans said in his written testimony. "At a standard less than 70 ppb, achieving the standard over a broad portion of the western US with current background ozone levels would be very difficult," he warned.
"To be fair, this issue has only arisen as background levels of ozone have continued to increase while EPA has simultaneously regulated ozone to lower and lower levels," observed Jeffrey R. Holmstead, a former EPA assistant administrator for air and radiation who now is a partner in Bracewell & Giuliani LLP's Washington office.
"Certainly, when the Clean Air Act was enacted back in 1970, and even when it was last amended in 1990, Congress did not appear to contemplate this issue – that background emissions would make it impossible for states to meet national ambient air quality standards," his written testimony continued. "Perhaps it is time for Congress to consider this problem, but I recognize that it is perhaps beyond the purview of this subcommittee."
Reducing allowed limits to 60 ppb concerns the US oil and gas industry because it could severely restrict development of potentially significant domestic resources in much of the country. Under such standards, 97% of the US population would live in places out of compliance and subject to new emissions reduction requirements, American Petroleum Institute Regulatory and Scientific Affairs Director Howard Feldman said on May 30.
"Needless to say, operating under such stringent requirements could stifle new investment necessary to create jobs," he said. "That could slow the economy or even nudge it into recession."
"With ozone concentrations falling, a lower standard is unnecessary and would jeopardize significant new manufacturing investment in many areas of the country," American Chemistry Council President Cal Dooley said on June 11. "[Chemical manufacturers] have announced plans for more than 110 projects representing $77 billion in capital spending, and other industries stand to benefit as the downstream effects of abundant, affordable shale gas supplies are felt."
Exceptional events
But other witnesses at the subcommittee's June 12 hearing said that regulatory mechanisms exist to consider background ozone impacts on total measured emissions. Concentrations at 60-70 ppb harm the environment and human health, said Russell Dickerson, a professor in the University of Maryland's Oceanic and Atmospheric Science Department. High ozone levels from natural causes in the West can be easily identified from unique chemical signatures, and EPA should designate them as exceptional events which don't count against attainment status, he suggested.
Obtaining scientific evidence to support such a designation requires scientific effort, Dickerson said in his written testimony. The National Aeronautics and Space Administration's Air Quality Applied Science Team already provides stratospheric intrusion and forest fire data, and is already working with western states on identifying exceptional ozone events "and would be happy to expand those efforts," he said.
In the integrated scientific assessment it issued in February, EPA recognized that background ozone concentrations in the US vary by region, altitude, and season, according to John Vandenberg, director of the agency's National Center for Environmental Assessment's North Carolina division.
US background ozone concentration estimates cannot be obtained directly from ambient ozone measurements because of long-range transportation from man-made pollution in North America, he said in his written statement. Air quality models are used to estimate background concentrations instead, an approach which EPA's Clean Air Scientific Advisory Committee supports, Vandenberg said.
Smith said that Utah has found EPA's exceptional events policy to be "an impossibly high hurdle", however. "Since 2008, [the state] has submitted 12 exceptional event demonstrations for particulate matter, requiring about 4,000 hours of technical work, that have not been approved by [EPA's] Region 8," she told the subcommittee. "There were many other events, including ozone levels affected by western wildfires that we did not even attempt to demonstrate as exceptional events because the technical criteria were too difficult to meet."
If the federal environmental regulator's exceptional events policy doesn't work for particulate matter, it certainly won't function well under the complicated science behind rural background ozone, she continued. "If EPA moves forward with a more stringent standard without workable measures to address background ozone, it will guarantee failure for Utah, leading to severe consequences for the state," Smith said.
