Several years ago, scientists hypothesized that a narrow spectrum of ultraviolet light called far-UVC could kill microbes without damaging healthy tissue. Far-UVC light at about 222 nanometers (nm) has a very limited range and cannot penetrate through the outer dead-cell layer of human skin or the tear layer in the eye, so it’s not a human health hazard. But because viruses and bacteria are much smaller than human cells, far-UVC light can reach their DNA and kill them. In the study, aerosolized H1N1 virus—a common strain of flu virus—was released into a test chamber and exposed to very low doses of 222nm far-UVC light. A control group of aerosolized virus was not exposed to the UVC light. The far-UVC light efficiently inactivated the flu viruses with about the same efficiency as conventional germicidal UV light. Continue reading
Tag Archives: light
There is no investment you can make which will pay you so well as the effort to scatter sunshine and good cheer through your establishment.
– Orison Swett Marden (1850-1924)
Scattering sunshine metaphorically is a great idea. The stress of the workplace places great burdens on people and spreading a little sunshine is a simple way to create a more positive environment. But scattering sunshine also has a far less romantic side to it.
Clouds and shaving cream are white, but they do not contain any white pigment. Driving through dense fog can be treacherous, but it’s just water! Bathroom mirrors also fog, especially if you take a really hot shower on a cold winter day. And titanium dioxide is a clear crystal, yet we call it a white pigment. Scattering of light explains all.
One can discuss scattering by pointing to detailed physics formulae, but that method produces more fog than clarity. I prefer the much simpler method that assumes that the brainy physicists have worked out all the details and that they can be trusted. If that works for you (and it certainly works for me), read on. Continue reading