This action seeks to address Defendant's excess ethylene oxide (EtO) emissions caused by the noncompliant operation of emission controls at its commercial sterilization facility in Salinas, Puerto Rico. EPA has alleged violations of the National Emission Standards for Hazardous Air Pollutants for EtO sterilization facilities, at 40 C.F.R. Part 63, Subpart O (NESHAP Subpart O), and the federally-enforceable requirements in the Puerto Rico Regulations for the Control of Atmospheric Pollution (RCAP), which are approved by EPA into the federally enforceable State Implementation Plan for Puerto Rico. EPA seeks relief to assure Defendant's compliance with the EtO emission limits in NESHAP Subpart O and other permitting requirements in the Puerto Rico RCAP, including operation of compliant pollution controls that are capable of reducing EtO emissions to within applicable limits.