The paper compares nitrogen oxide (NOx) control technology requirements under the U.S. 1990 Clean Air Act Amendments (CAAAs) with those in selected Pacific Rim countries. The CAAAs require reduction of NOx emissions under Titles I (requiring control of NOx from all source types for the purpose of attaining ambient air quality standards for NOx and ozone) and IV (requiring control of NOx from coal-fired utility boilers for the reduction of acid rain precursors). Title IV sets national emission standards for dry-bottom wall-fired and tangentially fired boilers based on low NOx burner technology, defined by EPA to include separated overfire air. Emission standards for other boiler types are to be promulgated by 1997. Title I controls, based on reductions necessary to reduce local and regional ambient levels of NOx and ozone, involve Reasonably Available Control Technology (RACT) as defined by EPA's Office of Air Quality Planning and Standards; however, emission levels are set by the states according to local conditions. Technologies defined as RACT include low NOx burner technology, selective non-catalytic modifications, and selective catalytic reduction. These and other combustion modifications and flue gas treatment technologies are described.