The EPA on Friday released draft air quality permits for Shell Oil’s exploratory offshore oil drilling operations in Alaska's Arctic.

EPA previously issued the two permits to Shell in spring 2010. These permits were then appealed by outside groups to EPA's independent Environmental Appeals Board, which overturned them in December. EPA’s announcement Friday triggers a 30-day public comment period to gather feedback on the permits, which would allow Shells’ drillship and supporting fleet of icebreakers, oil spill response vessels, and supply ships operations in the Chukchi and Beaufort Seas to begin drilling next year.

Shell's proposed exploration drilling operations would emit more than 250 tons of air pollutants a year. The federal permits would set limits on air pollution from its vessels.

EPA will accept public comments starting Wednesday on the revised draft permits and through Aug. 5. There will also be a public hearing in Barrow on Aug. 4. Final permits will be issued after comments from the public and key stakeholders are reviewed and considered.

EPA is currently working on two additional Clean Air Act permits for oil and gas exploration beginning in the 2012 and 2013 drilling seasons. Shell has also applied for a permit to operate its vessel, Kulluk, in the Beaufort Sea starting in 2012 and ConocoPhillips has applied for a permit for oil and gas exploration activities in the Chukchi Sea starting in 2013.