Which agency is responsible for enforcing regulations concerning refrigerants in the U.S.?

The U.S. Environmental Protection Agency (EPA) is the agency specifically tasked with enforcing regulations concerning refrigerants in the United States. This responsibility falls under the EPA's broader mandate to protect the environment and public health by regulating substances that can have harmful effects on the atmosphere, particularly concerning ozone-depleting substances and greenhouse gases. The EPA oversees the implementation of the Clean Air Act, which includes regulations concerning the use and disposal of refrigerants to minimize their impact on the environment.

The other agencies mentioned play important roles in their respective areas but do not have the primary responsibility for refrigerant regulations. NOAA focuses on weather, oceans, and atmospheric conditions; OSHA is concerned with workplace safety and health standards; and the DOE deals with energy policies and regulations, but not specifically with refrigerant management. Therefore, the EPA's role in enforcing refrigerant regulations makes it the correct choice in this context.