Summary/Abstract The overarching goal of this project is to protect the nation’s supply chain of critical medical devices that are sterilized using ethylene oxide (EtO). Despite the search for alternative approaches, a large fraction of single-use devices is sterilized with EtO. These devices, including catheters, heart valves, and tracheostomy tubes, are critical to routine and life-saving procedures and therapies. As regulations for EtO emissions become more stringent to protect workers and communities from harmful exposure, there is a significant risk that supply chains for critical devices will be disrupted, in turn threatening the health and well-being of the nation. The specific objectives of this project include the development of a novel photocatalytic system to mitigate EtO at levels that are hazardous but difficult to address with existing adsorptive and thermal catalytic approaches. Specifically, the technology addresses concentrations in the range of 5 ppm and below in sterilization facilities, transportation, and warehouses. These “fugitive emissions” are a significant contributor to overall emissions and directly impact workers and community safety. Objectives include determining operating conditions at which low concentrations of EtO (<5 ppm) are oxidized at 99% destruction and removal efficiency (DRE) by identifying the optimum photocatalyst and parameter space for achieving high DRE. The specific aims are: Aim 1) optimize a 100 CFM photoreactor fluid flow, optical power, and catalyst parameters for 99% EtO DRE at fugitive EtO concentrations, Aim 2) develop a 100 CFM system based on the photoreactor from Aim 1 that can address EtO emissions in a real-world environment, Aim 3) evaluate performance of the Aim 2 100 CFM system in a sterilization facility, and Aim 4) analyze the Aim 2 system operational lifetime factors. Various computational fluid dynamics and non-sequential optical models will be leveraged by the experimental efforts. Standard and cutting-edge detection approaches that are capable of measuring EtO into the low ppb and ppt ranges will be used in the experimental program.