In May, the Environmental Protection Agency (EPA) prepublished SNAP [Significant New Alternatives Program] Rule 23, which proposed listing multiple substitute refrigerants for refrigeration and air conditioning equipment. For refrigeration equipment, the proposed rule includes the narrowed use of HFOs, such as R-448A, R-449A, and R-449B, in new medium-temperature stand-alone units. For new residential and light commercial air conditioners and heat pumps, the proposed rule lists several mildly flammable (A2L) refrigerants, including R-454B and R-32, as acceptable, subject to use conditions.