Updated

ALBUQUERQUE, N.M. —  An environmental group is accusing the U.S. Environmental Protection Agency of not safeguarding public health in the West by failing to limit the transmission of air pollution across state lines.

The federal agency requires states to have plans aimed at addressing the interstate transport of ozone pollution and fine particles, but WildEarth Guardians said New Mexico and several other states do not have plans.

Jeremy Nichols, WildEarth Guardians' climate and energy program director, said his group will sue the agency if it fails to enforce the interstate transport requirements of the Clean Air Act.

"It's been an issue that has kind of been cast aside. It's not really important to the EPA," Nichols said. "... We're hopeful the EPA, now having this notice of intent to sue in front of them, will be a little more strict when it comes to dealing with the states on this issue."

The EPA issued a statement Monday saying it received the group's notice and would respond accordingly following a review.

WildEarth Guardians' concerns stem from a 2005 EPA finding that all 50 states had to adopt clean air plans to protect downwind states from ozone pollution and particles such as those found in smoke and haze.

EPA gave states a deadline of 2007, but Nichols said California, Colorado, Idaho, New Mexico, North Dakota, Oklahoma and Oregon are still without plans.

"We just want to see clean air. We just want to see this problem dealt with," he said. "We're not just trying to make bureaucrats do unnecessary work here."

New Mexico turned in its plan in 2007 but the EPA has yet to approve it, said Jim Norton, head of the state Environment Department's Environmental Protection Division.

"I don't know why they haven't dealt with it yet. It might not be at the top of their list, but we did our part," Norton said.

Norton said the issue of interstate transport of air pollution isn't a problem for New Mexico like it is in other states.

But WildEarth Guardians argues that pollution problems in the West are on the rise. The group says Denver, Phoenix, Los Angeles and other cities have violated clean air standards limiting ozone, and the problem is popping up in rural areas such as the Four Corners region — where New Mexico, Colorado, Arizona and Utah meet.

The region is home to two coal-fired power plants and the San Juan Basin, one of the largest natural gas fields in the nation.

Scott Tipton, a Republican lawmaker from Colorado, recently asked state officials to help reduce pollution in the region. He said excessive emissions have traveled across state lines, clogging the air and damaging the health of southwestern Colorado residents.

WildEarth Guardians in December petitioned EPA to force New Mexico, Arizona, California, Colorado, Idaho, Kansas, Montana, Nebraska, Nevada, North Dakota, Oklahoma, Oregon, South Dakota, Utah, Washington and Wyoming to revise their air quality regulations to strengthen ozone safeguards by 2013.

The group wants the agency to create a regional interstate commission to assess the degree of ozone pollution transport and strategies to combat the problem. The EPA has said it would review the petition.

According to WildEarth Guardians, all or portions of the 16 states are expected to exceed ozone pollution limits by 2018.