SALT LAKE CITY — An environmental group is suing the U.S. Environmental Protection Agency, claiming it hasn't pushed Utah hard enough to clean up air pollution across urban areas of northern Utah.

WildEarth Guardians says the EPA let Utah skip a December deadline to impose regulations.

Utah regulators say they needed more time to achieve emissions reductions. EPA officials have said Utah was making a good effort and wouldn't be penalized. The officials have changed their characterization of December's deadline, saying it was never formal.

WildEarth Guardians says Utah is dragging its feet.

The Utah Air Quality Board expects to finish clean-air plans by July.

The EPA had no comment on the lawsuit. Environmental groups frequently sue the EPA to force quicker changes.