EPA is promulgating emission standards and associated regulatory requirements for the control of emissions from locomotives and locomotive engines as required by the Clean Air Act section 213(a)(5). The primary focus of this rule is the reduction of emissions of oxides of nitrogen (NO<INF>X</INF>). The standards will take effect in 2000 and will ultimately result in a more than 60 percent reduction in NO<INF>X</INF> from locomotives. NO<INF>X</INF> is a precursor to the formation of ground level ozone, which causes health problems such as damage to lung tissue, reduction of lung function, and sensitization of lungs to other irritants, as well as damage to terrestrial and aquatic ecosystems. EPA is also promulgating standards for emissions of hydrocarbons (HC), carbon monoxide (CO), particulate matter (PM), and smoke. The overall cost-effectiveness of today's emissions standards is 158 dollars per ton of NO<INF>X</INF>, PM and HC reduced. Today's rule also includes a variety of provisions to implement the standards and to ensure that the standards are met in-use. These provisions include certification test procedures, and assembly line and in-use compliance testing programs. Also included in today's rule is an emissions averaging, banking and trading program to improve feasibility and provide flexibility in achieving compliance with the proposed standards. Finally, EPA is promulgating regulations that preempt certain state and local requirements relating to the control of emissions from new locomotives and new locomotive engines, pursuant to Clean Air Act section 209(e).