Are GUV wands effective for disinfecting surfaces?

Are GUV wands effective for disinfecting surfaces?

Hand-held, compact GUV products (see Figure 1) have been marketed for more than a decade for disinfecting small objects such as cell phones. Most of these emit less than 2 mW·cm-2 of 254-nm UV-C at contact, meaning that the wand has to be held to the surface for several seconds for an effective multi-log unit disinfection. Waving it over an object such as a postcard for one second will not provide reliable disinfection. These products typically employ a safety switch that senses when the emission is not directed downward (away from the eyes) and shuts off if turned upward. Even if safely used, these might provide a false impression of effective disinfection.