A Washington, DC-based environmental group has filed a lawsuit seeking to force the federal Environmental Protection Agency to comply with a previous court order to regulate air emissions from cement kilns nationwide, including the one at Dragon Products Co. in Thomaston.

Earthjustice, which filed the lawsuit last week on behalf of the Sierra Club, says there are 137 producers of Portland cement in the United States. Portland cements, known for their levels of strength and durability, are the most popular cements produced in the United States.

In Knox County, a group calling itself Neighbors for a Safe Dragon organized in recent months to raise similar concerns about Dragon’s operations. Among Neighbors’ concerns are possible toxic chemicals in the cement company’s air emissions and from its cement kiln dust pile.

Earthjustice is a nonprofit law firm for the environment, representing -- for free -- hundreds of public-interest clients, large and small, according to its Web site. The organization was founded in 1971 as Sierra Club Legal Defense Fund.

Nearly four years ago, the group won a lawsuit in the U.S. Court of Appeals for the D.C. Circuit in which EPA was ordered to issue regulations to reduce air pollution from cement kilns, Earthjustice spokesman Jared Saylor said Sunday. EPA has failed to act, he said.