California, Arizona, Oregon, New Mexico and 13 other Midwestern and Eastern states said the U.S. Environmental Protection Agency was \u201cunreasonably delaying\u201d its rewrite of its carbon dioxide pollution rules as required by the U.S. Supreme Court last April. \u201cWe once again urge EPA immediately to begin the regulatory process by publishing formal notice of EPA\u2019s conclusion that greenhouse gas emissions from motor vehicles and other sources \u2018cause or contribute to air pollution which may reasonably be anticipated to endanger public health or welfare\u2019,\u201d the states wrote in a January 24 letter to federal agency administrator Stephen Johnson. In last year\u2019s Massachusetts v. EPA decision, the high court held the federal agency was supposed to regulate greenhouse gases unless it could prove the emissions did not harm human and environmental health. It ordered the agency to propose new regulations in keeping with the April 2007 ruling. EPA said it intended to launch a regulatory plan on December 10, 2007. However, there has been no regulatory action since then, the letter noted. \u201cThere is no valid reason for EPA to continue to delay moving the regulatory process forward in this manner,\u201d it said.