Inspector General Arthur Elkins Jr. said the EPA has failed to directly measure emissions from some pieces of equipment and processes, and some estimates it does have are of "questionable quality."
"With limited data, human health risks are uncertain, states may design incorrect or ineffective emission control strategies, and EPA's decisions about regulating industry may be misinformed," Elkins said.
The EPA, under President Barack Obama, has stepped up regulation of natural gas drilling, which has been booming thanks to hydraulic fracturing, or fracking. About 25,000 wells a year are being fracked, a process in which water, chemicals and sand are injected at high pressure underground to release trapped natural gas.
Obama also wants to expand natural gas production, as long as it doesn't damage the environment.
Oil and gas production, from the well site to processing plants to storage tanks and transmission lines, releases toxic and cancer-causing air pollutants, smog-forming gases and methane, a potent greenhouse gas blamed for global warming.
The oil and gas industry has said the EPA has overestimated emissions of methane and argued that they already were working to reduce pollution, without the agency's intervention.
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The EPA last year issued the first-ever standards to control smog- and soot-forming gases from gas wells site, and updated existing rules to reduce cancer-causing pollution, such as benzene, from other equipment.
The agency, in response to the report, agreed to develop a comprehensive strategy to improve its pollution figures.
An industry association, America's Natural Gas Alliance, had not seen the report and had no comment late Thursday.
Inspector general's report:
Press; By DINA CAPPIELLO]
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