Hat tip for the David Brenner link. The bottom of that page reads:

    Over the past six years, we have been working on a very exciting new approach to killing drug-resistant bacteria - superbugs- , as well as airborne viruses such as influenza, using a unique type of ultra-violet light. We have always known that ultraviolet light can efficiently kill all microbes, but conventional germicidal ultraviolet light is hazardous to our health, causing skin cancer and cataracts. We have identified a particular wavelength of UV light that has the best of both worlds - it's safe and it kills microbes - including superbugs.

While he doesn't say it directly, I guess he is talking about 222nm UV.