https://stream.echo6.co/videos/watch/41b8fd64-5137-44b2-8926-34143d2471a5 This is a very simple unit internally. It just has an electronic ballast and custom mercury vapour UVC germicidal tube, and relies on thermal convection to gently and silently circulate air through the unit. Other versions have a fan to force air through faster. As air passes through the unit, any bacteria, spores and viruses are deactivated and volatile aromas are oxidised, resulting in more sterile air. This unit has a couple more tricks up its sleeve though. Aside from the interesting aluminium shrouds to limit the amount of UVC light that can escape the unit, it also has a set of titanium dioxide coated baffles designed to cause air turbulence. Titanium dioxide is commonly used as a very white pigment in paints, but also has the unusual characteristic of exhibiting a photocatalytic reaction on its surface when exposed to UV light. That results in the formation of hydroxyl radicals (a molecule composed of one atom of hydrogen and one of oxygen) which is a very short lived but highly reactive molecule that reverts back to a more stable form almost instantly, but can oxidise airborne contaminants in the process. This unit also uses an unusual UVC tube that has two types of quartz/uviol glass that are spliced together. The long section only passes 254nm UVC and the short section also passes the 184nm wavelength giving a small extra output of ozone for increased effect throughout the space it's in. It's quite odd that a unit that has been in use long enough for the tube to have failed completely, still has immaculately white titanium dioxide baffles. It may be a self-cleaning effect associated with photocatalysis. Now for the medical stuff. Contrary to popular belief, UVC poses a low risk of skin cancer. It got that reputation because it will cause very serious surface irritation of skin and eyes. But in reality the wavelength is so short that it can't penetrate deep enough into the skin to reach the critical layers. UVA and UVB both pose a much higher risk of causing subdermal damage. Always remember not to look at a lit UVC bulb or its reflection from shiny surfaces. It will rapidly cause surface damage to skin and eyes, leading to sunburn effects. The eyes will not react immediately, but after some time they will feel like they are filled with sand. This effect will quickly wear off depending on the exposure level. It may be possible to get anesthetic eye drops to help with the discomfort if needed. It's so unpleasant that you will not want to risk it again. Almost every plastic and glass will block UVC light, so standard safety goggles will usually protect your eyes. You can get phosphor coated UVC test cards to check that. Titanium dioxide has been used as a paint pigment and food colourant for a long time, but there are now concerns that nanoparticles of TiO2 (titanium dioxide) could pass through the blood-brain barrier and pose health problems in some situations. Most of the research in this area has been done on lab animals consuming the pigment, and it's not known if it poses the same risk to humans. As a food additive (E171) it has been banned in Europe and many other countries for several years, but is still used in the UK and USA. In this application there is no significant risk as it is not being ingested. I got this unit secondhand on eBay, and it still commanded a respectable price. This one was £45 in a well-used condition and with a dead fluorescent tube. It uses a 2G7 lamp holder, and I ended up retrofitting a different one so that it could use a cheap 9W PLS aquarium UVC tube, which lacks the ozone section. UVC tubes gradually degrade their quartz/uviol glass over time, and although they may seem just as bright as usual, this can greatly reduce the amount of UVC light emitted. As such, they should be changed every year or 10,000 hours of use. The degradation of the quartz on this tube was visible. Mercury vapour tubes are still the cheapest, most reliable and most efficient source of UVC light for applications like this. LED sources of UVC are not currently viable for this application. If you enjoy my videos, then supporting the channel on Patreon helps keep it independent of YouTube's quirks, avoids intrusive mid-video adverts, gives early access, bonus footage and regular quiet Patreon live streams. https://www.patreon.com/bigclive Alternatively, for a single coffee contribution you can use PayPal:- https://www.paypal.com/paypalme/bigclive #ElectronicsCreators Mon, 13 Apr 2026 22:51:13 GMT https://validator.w3.org/feed/docs/rss2.html PeerTube - https://stream.echo6.co https://stream.echo6.co/client/assets/images/icons/icon-512x512.png https://stream.echo6.co/videos/watch/41b8fd64-5137-44b2-8926-34143d2471a5 All rights reserved, unless otherwise specified in the terms specified at https://stream.echo6.co/about and potential licenses granted by each content's rightholder.