Nine groups are challenging Shell Oil’s Arctic air permit, granted by the Environmental Protection Agency to Shell Oil for a drilling ship in Alaska's Chukchi Sea, in a federal appeals court.
The environmental and Alaska Native groups want the permit sent back to the EPA for reconsideration.
Earthjustice attorney Colin O'Brien says the EPA failed to make sure all standards were met for a major new source of pollution in the Arctic.
Shell hopes to use the ship to drill three exploratory wells in the Chukchi Sea this summer.
Shell spokeswoman Kelly op de Weegh says Shell retrofit its catalytic exhaust systems and will use ultra-low sulfur fuel on all of its vessels. She says Shell is confident in EPA findings that emissions will not harm the air shed.