The Environmental Protection Agency (EPA) is taking direct final action to revise the regulations for the Acid Rain Nitrogen Oxides Emission Reduction Program under title IV of the Clean Air Act in response to a remand by the U.S. Court of Appeals for the District of Columbia Circuit. In December 1996, EPA issued regulations setting nitrogen oxides (NO<INF>X</INF>) emission limits for specified types of existing, coal-fired boilers, including cell burner boilers, that are subject to such limits starting in 2000. In February 1998, the Court upheld the regulations except for one provision addressing what boilers qualify as cell burner boilers. The Court vacated and remanded that provision. EPA is revising the regulations, consistent with the Court's decision, to treat, as a cell burner boiler, any boiler subject to the limits starting in 2000, constructed as a cell burner boiler, and converted to the burner configuration of a wall-fired boiler. Under the regulations, a cell burner boiler must meet an annual average NO<INF>X</INF> emission limit of 0.68 lb/mmBtu. The NO<INF>X</INF> emission limits under title IV will reduce the serious, adverse effects of NO<INF>X</INF> emissions on human health, visibility, ecosystems, and materials.