This action will address the agency's risk and technology review (RTR) of the National Emission Standards for Hazardous Air Pollutants (NESHAP) for Hazardous Waste Combustors (HWC NESHAP). The HWC NESHAP, 40 CFR part 63, subpart EEE, was promulgated pursuant to section 112(d) of the Clean Air Act (CAA); EPA finalized the current standards in October 2006. The NESHAP established emission limitations and work practice requirements based on maximum achievable control technology for controlling emissions of hazardous air pollutants (HAP). The HAP emitted from hazardous waste combustors include metal HAP as well as volatile organic HAP, polycyclic organic material, and halogen acids. This action will implement the residual risk review requirements of CAA section 112(f)(2) and the technology review requirements of CAA section 112(d)(6). The statute directs the EPA to promulgate emission standards under CAA 112(f)(2) if such standards are required to provide an ample margin of safety to protect public health or to prevent, taking relevant factors into account, an adverse environmental effect. Any such standards are to be promulgated within 8 years after promulgation of MACT standards under CAA section 112(d). CAA section 112(d)(6) requires the EPA to review and revise the MACT standards as necessary, taking into account developments in practices, processes and control technologies, no less often than every 8 years. The EPA has a deadline for final rulemaking action to be completed by December 31, 2025.