State officials and environmental groups have filed a lawsuit seeking to force the Environmental Protection Agency and the White House to determine whether greenhouse gas emissions endanger public health. The suit comes one year after the Supreme Court ruled the EPA has the authority under the Clean Air Act to regulate the emissions. The court found the EPA had violated the Clean Air Act by improperly declining to regulate new-vehicle emissions standards to control the pollutants that scientists say contribute to global warming. But one year later, the Bush administration has yet to take any action on the ruling, despite a recent EPA task force finding that the emissions endanger public health.