"Given the central role of these publicly-funded analyses in providing justification for major, costly EPA regulations, it is imperative that this information be open and transparent," the letter read.
Americans, the letter said, "have a right to know whether EPA's new rules are based on sound science or a partisan agenda."
EPA spokeswoman Alisha Johnson said in a statement that the agency has provided Congress with all of the information it currently has available, and has requested additional data from outside researchers. Those researchers, including some at Harvard University, have declined to release the data collected 20 years ago citing legally binding confidentiality agreements with study participants.
Stewart and Smith counter that these claims "ring hollow" given that they have been asking the agency for this data for more than two years.
The committee's request sounds much like the challenges of climate skeptics aiming to discredit the science behind global warming. They hint at the possibility that faulty and "hidden" data has been used to justify regulations under the Clean Air Act that cover all types of air pollution, including summer smog, coal-plant emissions related to regional haze and the sooty pollution that plagues Wasatch Front valleys in the winter.
The letter comes weeks after the Obama administration ordered the EPA to propose limits on carbon dioxide emissions from coal- and gas-fired plants, angering those in the fossil-fuel industry and their Republican allies. It also comes up as the Obama administration scrutinizes scientific studies on the health impacts of ozone pollution, with an eye on possibly tightening allowable limits.
Restrictions on ozone levels, Stewart and Smith argue in the letter, "are expected to be some of the most costly regulations the federal government has ever issued."
These regulations will likely have a significant effect in Utah, a state which suffers from poor air quality. Stewart has argued previously that naturally occurring levels of ozone are much higher in Western states due to the area's topography and the frequency of wildfires.
The current acceptable ozone standard is 75 parts per billion, a level all 29 Utah counties are able to meet. The agency has yet to determine how strict the new regulation will be, but Utah lawmakers are concerned that it may set an impossible threshold. Counties that fail to comply with EPA standards encounter construction restrictions and reduced federal funding.
Smith and Stewart suggest that a reluctance to release the data, which support the health-benefit claims behind emission reduction, casts doubt on the legitimacy of the agency's research, writing: "If EPA has nothing to hide, why not provide this information to Congress and the American people?"
Johnson said that peer-reviewed science "consistently shows that particulate matter and ozone are linked to harmful health and environmental effects," adding that the EPA will continue to take into account relevant research in the field.