The EPA is proposing to revoke the Fiscal Year 2019 Clean Air Act (CAA) section 105 grant awarded to the Puerto Rico Department of Natural and Environmental Resources (PRDNER) because it has failed to satisfy the statutory maintenance of effort (MOE) requirement for that year. The EPA is providing prior notice of its intent to revoke PRDNER's Fiscal Year 2019 Clean Air Act section 105 grant. When the proposed action is final, PRDNER will be eligible to receive future CAA section 105 grants to support its air pollution control program.