The EPA issued a final air quality permit for Shell to conduct oil and natural gas exploration off the coast of Alaska. The permits give Shell the authority to operate its Discover drillship and associated exploration and oil-spill response vessels for up to 120 days every year starting next year.
Environmental groups say they worry about the consequences of potential disasters in arctic waters.
The EPA said that, under the new permits, Shell is committed to reducing fleet emissions "in most key air pollutants" by more than 50 percent of the levels allowed for in their 2010 permits.
"These reductions are largely due to new emissions controls Shell added to meet the new nitrogen dioxide standard that went into effect in 2011," the EPA said.
Melting sea ice brought on in part by climate change is exposing vast areas believed to contain oil and natural gas.
Peter Slaiby, vice president of Alaskan operations at Shell, said during July testimony before a Senate committee on commerce that his company understood the risks of work in the arctic.
U.S. Coast Guard Adm. Robert Papp in his testimony, however, said his agency was starting from "ground zero" in terms of response capabilities in arctic waters.