This action promulgates standards for the second phase of the Nitrogen Oxides Reduction Program under Title IV of the Clean Air Act (``CAA'' or ``the Act'') by establishing nitrogen oxides (NO<INF>X) emission limitations for certain coal-fired electric utility units and revising NO<INF>X emission limitations for others as specified in section 407(b)(2) of the Act. The emission limitations will reduce the serious adverse effects of NO<INF>X emissions on human health, visibility, ecosystems, and materials.