The EPA wants to define a threshold for the amount of pollution required to pose a significant threat to public health and prompt controls, a move that could raise questions about limits on oil and gas methane emissions, the agency’s air chief said.
The Environmental Protection Agency in a footnote in its Dec. 6 proposal to reconsider Obama-era carbon dioxide controls for new and modified power plants opened the door for comment about whether the agency has made an adequate finding that greenhouse gases from the power sector must be regulated. That determination is twofold—that greenhouse gases endanger public health and welfare; and that such emissions from the power sector significantly contribute to overall pollution.
But the EPA may not be targeting the basis for the Obama-era power sector rule or the pivotal 2009 endangerment finding underpinning the agency’s regulation of greenhouse gases. Instead, the EPA is trying to make a determination about the scope of its authority and whether a threshold exists for pollution to become a major contributor to endangerment, Bill Wehrum, the agency’s air chief, told Bloomberg Environment in an exclusive interview.
The question is only a footnote in the EPA’s power plant proposal because the sector ranks second-highest, behind transportation, in greenhouse gas emissions in the U.S., Wehrum said. But the agency wants people to be thinking about what the legal standard is and whether it can be satisfied in other source categories the EPA regulates, including oil and gas operations, he said.
The EPA regulates power plant carbon emissions and oil and gas methane emissions under section 111 of the Clean Air Act.
The EPA in September proposed to relax Obama-era limits on methane, a potent greenhouse gas, from new oil and gas drilling operations. Oil and gas industry groups, though, have urged the EPA to rewrite the rule to remove methane as a regulated pollutant altogether.
“It will be a closer question” of whether the oil and gas sector emits enough methane to qualify as a significant contribution, Wehrum said.
“When the time comes, I’m sure we’ll ask the same question in that context, but it will be much more relevant in that context because we’re dealing with a smaller slice of the emissions inventory,” he added.
But critics say Wehrum’s approach reverses the EPA’s decades-old interpretation of the Clean Air Act.
The EPA has historically read Section 111 to require a finding that a source category, such as power plants or oil and gas operations, endangers public health and welfare, Joseph Goffman, former senior counsel in the EPA’s air office during the Obama administration, told Bloomberg Environment. Once a source category is listed under the statute as a significant contributor to air pollution, the EPA can regulate any pollutant from that sector, he added.
Wehrum is “introducing a bait-and-switch in terms of a long-standing interpretation of” the air law, Goffman, now executive director at Harvard University’s Environmental and Energy Law Program, added.
The air chief, though, said he believes the EPA must make for each specific pollutant findings that the pollutant endangers public health and that a particular sector’s emissions contribute significantly to the problem.
“What is a significant contribution? How is it different from a mere contribution? That’s the question,” Wehrum said.
The stakes are the prospect that the EPA could be required to regulate methane emissions from existing oil and gas drilling operations, Goffman said.
The Obama EPA had begun that process in 2016, working to collect data from the industry about emissions from existing sources, but former EPA Administrator Scott Pruitt withdrew that request in the first days of his tenure in 2017.
“They want to blow up the 2016 rule, so that any successor administration has to start all over again,” Goffman said.
But he added that even if the EPA must make a finding of significant contribution, oil and gas methane emissions pass that test. Goffman pointed to the potency of methane, which is dozens of times more potent than carbon dioxide.
“The oil and gas sector’s methane is well above any plausible significance threshold,” he said.
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