This action would list a number of substances as acceptable, subject to use conditions, where such alternatives may be used safely and do not pose significantly more risk than other available substitutes when used in accordance with the proposed restrictions. This action also would list as unacceptable alternatives that cannot be used as safely as other available alternatives. In addition, it would modify the listing status for certain alternatives from acceptable to unacceptable or acceptable, subject to narrowed use limits, where other alternatives are available that pose lower overall risk to human health and the environment. This action also would exempt propane in certain refrigeration end-uses from the venting prohibition under Clean Air Act section 608. In addition, this action would 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. Affected industrial sectors under consideration include refrigeration and air conditioning, foam blowing, and fire suppression and explosion protection.