A cold plasma system for treating a region of a biological surface, the system comprising: a housing; a first air conduit within the housing; a first electrode configured proximately along the first air conduit; a second electrode configured proximately along the first air conduit (164, 514, 512, 714, 711, 712) and opposite from the first electrode; a source of alternating current electrically connected with the first electrode, wherein the source of alternating current is configured to generate a cold plasma in the air conduit (164, 514, 512, 714, 711, 712); characterized in that the system further comprises: a reservoir (180, 520, 720) configured within the housing, wherein the reservoir (180, 520, 720) is in a fluid communication with the air conduit (164, 514, 512, 714, 711, 712), and wherein the reservoir (180, 520, 720) is configured for holding the cold plasma; and a cartridge containing a plasma precursor, wherein the cartridge is in a fluid communication with the air conduit (164, 514, 512, 714, 711, 712), the system further comprising: a first air mover configured to transport the cold plasma from the first air conduit toward the reservoir (180, 520, 720); a second air conduit in a fluid communication with the reservoir (180, 520, 720) and the first air conduit; a second air mover configured to transport the cold plasma from the reservoir (180, 520, 720) toward the cartridge; and a controller configured to control a speed of rotation of the first air mover and a speed of rotation of the second air mover based on a difference between a present concentration and a target concentration of the cold plasma in the reservoir (180, 520, 720), wherein the target concentration is selected at least in part based on a half-life of the cold plasma. a housing; a first air conduit within the housing; a first electrode configured proximately along the first air conduit; a second electrode configured proximately along the first air conduit (164, 514, 512, 714, 711, 712) and opposite from the first electrode; a source of alternating current electrically connected with the first electrode, wherein the source of alternating current is configured to generate a cold plasma in the air conduit (164, 514, 512, 714, 711, 712); characterized in that the system further comprises: a reservoir (180, 520, 720) configured within the housing, wherein the reservoir (180, 520, 720) is in a fluid communication with the air conduit (164, 514, 512, 714, 711, 712), and wherein the reservoir (180, 520, 720) is configured for holding the cold plasma; and a cartridge containing a plasma precursor, wherein the cartridge is in a fluid communication with the air conduit (164, 514, 512, 714, 711, 712), the system further comprising: a first air mover configured to transport the cold plasma from the first air conduit toward the reservoir (180, 520, 720); a second air conduit in a fluid communication with the reservoir (180, 520, 720) and the first air conduit; a second air mover configured to transport the cold plasma from the reservoir (180, 520, 720) toward the cartridge; and a controller configured to control a speed of rotation of the first air mover and a speed of rotation of the second air mover based on a difference between a present concentration and a target concentration of the cold plasma in the reservoir (180, 520, 720), wherein the target concentration is selected at least in part based on a half-life of the cold plasma. a reservoir (180, 520, 720) configured within the housing, wherein the reservoir (180, 520, 720) is in a fluid communication with the air conduit (164, 514, 512, 714, 711, 712), and wherein the reservoir (180, 520, 720) is configured for holding the cold plasma; and a cartridge containing a plasma precursor, wherein the cartridge is in a fluid communication with the air conduit (164, 514, 512, 714, 711, 712), the system further comprising: a first air mover configured to transport the cold plasma from the first air conduit toward the reservoir (180, 520, 720); a second air conduit in a fluid communication with the reservoir (180, 520, 720) and the first air conduit; a second air mover configured to transport the cold plasma from the reservoir (180, 520, 720) toward the cartridge; and a controller configured to control a speed of rotation of the first air mover and a speed of rotation of the second air mover based on a difference between a present concentration and a target concentration of the cold plasma in the reservoir (180, 520, 720), wherein the target concentration is selected at least in part based on a half-life of the cold plasma.