In various embodiments, provided are topical gas delivery systems and methods for promoting wound healing. A provided gas delivery system comprises a gas reservoir comprising at least one chamber adapted to contain one or more therapeutic gases selected from NO, CO, O2, air, or combinations thereof, and at least one gas permeable membrane operably coupled to the reservoir. A provided method comprises using a provided gas delivery system to deliver the one or more therapeutic gases to a wound site such that a NO/ONOO− ratio suitable for promoting wound healing is achieved at the wound site.