protection of stratospheric ozone proposed new listings of substitutes changes of listing status and reinterpretation of unacceptability for closed cell foam products under the significant new alternatives policy program and revision of clean air act section 608 venting prohibition for propane 101 pages in english prepursuant to the u.s. environmental protection agencys epa significant new alternatives policy program this action proposes to list a number of substances as acceptable subject to use conditions to list several substances as unacceptable and to modify the listing status for certain substances from acceptable to acceptable subject to narrowed use limits or to unacceptable. specifically this action proposes to list as acceptable subject to use restrictions propane and hfo-1234yf in the refrigeration and air conditioning and 2-bromo- 3 3 3-trifluoroprop-1-ene in the fire suppression and explosion protection sectors to list as unacceptable certain hydrocarbons and hydrocarbon blends in specific end-uses in the refrigeration and air conditioning sector and to modify the listing status for certain high- global warming potential alternatives for certain end-uses in the refrigeration and air conditioning foam blowing and fire suppression and explosion protection sectors. this action also proposes to exempt propane in certain refrigeration end-uses from the clean air act section 608 prohibition on venting release or disposal on the basis of current evidence that its venting release or disposal does not pose a threat to the environment. in addition this action proposes to apply unacceptability determinations for foam-blowing agents to closed cell foam products and products containing closed cell foam that are manufactured or imported using these foam-blowing agents. this action also proposes to clarify the listing for powdered aerosol d stat- xsupreg which is currently listed as both acceptable and acceptable subject to use conditions by removing the listing as acceptable subject to use conditions. pre