The Environmental Protection Agency (EPA) is approving a State Implementation Plan (SIP) revision concerning nitrogen oxides (NO<INF>X</INF>) emissions submitted by the State of Tennessee, through the Tennessee Department of Environment and Conservation (TDEC), through a letter dated December 19, 2019, which revises the Tennessee Air Pollution Control Rule (TAPCR) titled ``NO<INF>X</INF> SIP Call Requirements for Stationary Boilers and Combustion Turbines'' (TN 2017 NO<INF>X</INF> SIP Call Rule) to correct the definition of ``affected unit'' and to clarify requirements related to stationary boilers and combustion turbines. EPA is also converting the conditional approval of the TN 2017 NO<INF>X</INF> SIP Call Rule to a full approval.