The Environmental Protection Agency (EPA) is approving a state implementation plan (SIP) revision submitted by the Commonwealth of Pennsylvania on behalf of the Allegheny County Health Department (ACHD). The revision updates Allegheny County's portion of the Pennsylvania SIP, which includes regulations concerning sulfur content in fuel oil. This revision pertains to the reduction of the maximum allowable sulfur content limit for Number 2 (No. 2) and lighter commercial fuel oil, generally sold and used for residential and commercial furnaces and oil heat burners for home or space heating, water heating or both, from the current limit of 500 parts per million (ppm) to 15 ppm. EPA is approving these revisions to the Pennsylvania SIP in accordance with the requirements of the Clean Air Act (CAA).