Maryland officials won't be joining New York and a handful of other Northeastern states that recently filed a lawsuit against the Environmental Protection Agency demanding it hold other states responsible for the air pollution they send downwind.
"Maryland is working outside of the courtroom with EPA and other states to reduce interstate smog and we hope those efforts will be more effective than the filing of legal papers over the timing of EPA's decision," Ben Grumbles, secretary of the Maryland Department of the Environment, said in a statement.
Maryland was among eight states that asked the EPA in 2013 to require Midwestern and Southern states to do more to reduce the pollution that crosses their borders. But the agency has yet to act on that petition.
"Our coalition has waited almost three years for EPA to decide on whether it will use its legal authority to require upwind states to stem their contribution to the smog pollution," New York Attorney General Eric T. Schneiderman said in announcing the lawsuit.
Connecticut, Massachusetts, New Hampshire, Rhode Island and Vermont joined New York in filing the suit in a federal court in New York City.
An EPA spokeswoman said the agency will review and respond to the lawsuit.
Those six states, plus Delaware, Maine, Maryland, New Jersey, Pennsylvania and the District of Columbia, make up a group known as the "Ozone Transport Region." A commission overseeing the region works to coordinate air pollution reductions in a part of the country where congestion and density make air quality uniformly poor.
They had asked EPA to add nine more states to the group, arguing they aren't taking responsibility to their pollution contributions: Illinois, Indiana, Kentucky, Michigan, Ohio, Tennessee, Virginia, West Virginia and North Carolina.
North Carolina filed its own lawsuit against the EPA in March, asking the agency to make a decision on the petition. Officials there called the Northeast states' original complaint politically motivated and an effort to pass blame for poor air quality.
A spokesman for Grumbles said Maryland officials are "more focused on helping EPA make the right decision rather than signing onto legal papers."
One local air quality advocate said he wondered why the state chose not to join the lawsuit and hoped the EPA would approve the states' original request anyway.
"I'm very curious why they didn't, but maybe they have a good reason for it," said David Smedick, who leads the Sierra Club's Beyond Coal campaign in Maryland. "I hope the other states are enough to spur EPA to act."
Maryland environment officials estimate that as much as 70 percent of the state's air pollution flows in from outside the state. Pollutants such as ozone, created when heat and sunlight cause chemical reactions within emissions from vehicles, industry and power plants, can cause breathing problems and contribute to heart and lung diseases.
The EPA found this summer that the area around the Herbert A. Wagner Generating Station in Pasadena is not meeting federal standards for the pollutant sulfur dioxide, but state officials disagree with that finding.
The Associated Press contributed to this article.