the_newsbeagle writes:
Remember back in April when Trump was promoting ultraviolet light as a cure for COVID-19? Here's a quote: "Supposing you brought the light inside the body... the whole concept of the light, the way it kills it in one minute — that's pretty powerful." Since then, often-dangerous misinformation has circulated about whether people can use UV to protect against the coronavirus.
To combat the bad info, this article from IEEE Spectrum explains what UV light can actually do. It starts by clarifying what kind of UV light we're talking about:Ultraviolet light lies in a region of the electromagnetic spectrum beyond indigo and violet. Anyone who’s read the label on a bottle of sunscreen knows the UV wavelengths that give you a suntan or a sunburn are called UV-A (with wavelengths between 400 and 315 nanometers) and UV-B (315 to 280 nm). Germicidal UV tech focuses on shorter, more energetic UV wavelengths, known as UV-C, which lie between 280 and 100 nm. The Earth’s ozone layer prevents virtually all UV-C light from reaching us. So microbes and viruses (and everything else, really) evolved for millions and billions of years without ever being exposed to these wavelengths.
Since UV-C can cause skin caner and cataracts in humans, the mercury-vapor lamps and LEDs that emit the light have to be used carefully. They've been used to sterilize the air near the ceilings of rooms, to blast operating rooms and airplanes when there are no people present, and to clean personal protective equipment. But researchers are now trying out a more versatile type of UV light.
Given the harmful effects of 254-nm UV-C, scientists are exploring the higher-energy wavelength of 222 nm, in the far-UV region. This wavelength has been found to kill viruses and bacteria, and initial studies show that it’s substantially safer than photons in the 254-nm range. In fact, far-UV may be able to safely bathe an entire room in sterilizing light, even with people present.
