ANCHORAGE — The Environmental Protection Agency has agreed to an August deadline on whether to accept or reject a state plan to clean up heavily polluted Fairbanks air.

The agreement settles the first of two lawsuits filed against the agency by a pair of advocacy groups, Citizens for Clean Air and the Sierra Club, aimed at forcing the EPA enforce deadlines for a state cleanup of fine particulate, a pollutant that can cause heart attacks, decreased lung function and premature death.

Pamela Miller, director of Alaska Community Action on Toxics, said in a statement she was pleased that the court will enforce the deadlines.

“We hope that this consent decree results soon in real action on the ground to address the public health crisis that the people of Fairbanks are suffering as a consequence of the polluted air,” she said.

An EPA decision on the state plan was due nearly a year ago on Feb. 18. Meeting the deadline was complicated by the complexity of the issue and a national lawsuit challenging how EPA regulated fine particulate, said Tim Hamlin, EPA Region 10 director of the office of air and waste.

The EPA has agreed to propose to accept or reject a state cleanup plan by Jan. 19. After a comment period, the EPA must take final action by Aug. 28.

Kenta Tsuda, an attorney for the environmental law firm Earthjustice, who is representing the plaintiffs, said his clients believe the cleanup plan is flawed and should be revised. The state plan, for example, rejected a ban on the sale of green firewood, which when burned emits more particulate than seasoned wood.

Fine particulate is a mix of solid particles and liquid droplets that can be inhaled deep in the lungs.

In November 2009, the EPA designated the Fairbanks North Star Borough an area of “moderate” non-attainment. The agency was required to review progress after six years, and if problems lingered, consider reclassification of Fairbanks to a “serious” non-attainment area.

That reclassification review was due at the end of June, and when the EPA missed that deadline, the same two groups filed a second lawsuit. A reclassification as a “serious” non-attainment area would mean tougher provisions to clean up Fairbanks air.

Hamlin said the agency is moving toward reclassifying Fairbanks to a “serious” non-attainment area.

The air pollution around Fairbanks is brought on by extreme cold and geography. Hills surrounding Fairbanks create a bowl effect. In a meteorological phenomenon known as an inversion, cold air along the ground can be capped by a layer of warmer air, trapping emissions.

Wood- and coal-burning stoves, vehicles and coal-fired power plants emit particulate. Some Fairbanks residents burn wood as a cheaper alternative to expensive oil.

The sources contribute to fine particulate levels that at times spike to the highest levels in the nation and regularly exceed federal limits.