The Environmental Protection Agency (EPA, the Agency) is amending the regulations promulgated as part of the National Recycling and Emission Reduction Program under section 608 of the Clean Air Act. EPA is amending those regulations to exempt certain refrigerant substitutes, listed as acceptable subject to use conditions in regulations promulgated as part of EPA's Significant New Alternative Policy program under section 612 of the Act, from the prohibition under section 608 on venting, release or disposal on the basis of current evidence that their venting, release or disposal does not pose a threat to the environment. Specifically, EPA is exempting from the venting prohibition isobutane (R-600a) and R-441A, as refrigerant substitutes in household refrigerators, freezers, and combination refrigerators and freezers, and propane (R-290), as a refrigerant substitute in retail food refrigerators and freezers (stand-alone units only).