The Environmental Protection Agency (EPA) is taking final action to approve revisions to the Antelope Valley Air Quality Management District (AVAQMD), Eastern Kern Air Pollution Control District (EKAPCD), and Yolo-Solano Air Quality Management District (YSAQMD) portions of the California State Implementation Plan (SIP). These revisions concern emissions of oxides of nitrogen (NO<INF>X</INF>) from boilers, steam generating units, process heaters, and stationary internal combustion engines. We are approving local rules that regulate these emission sources under the Clean Air Act (CAA or the ``Act'').