It’s like somebody wants to make sure I have nightmares if I manage to fall asleep.
After my first post about the lovely sanitary conditions in open air food markets in a hot country: First the mystery story, then the horror story, I saw another one that had me heading for the toilet.
This one’s potentially more dangerous/scary, as it involves a scam/con regarding the disinfectant properties of UV light being perpetrated by some Chinese suppliers online. I say ‘suppliers’, but it’s hard to know where blame/intent lies in the supply chain.
But first, some images to set the scene.
First, a street scene spotted in China a few days ago, probably one of the more worrying examples. No apparent hygiene, meat hanging openly out into the street, not even using disposable plastic gloves when handling. But similar to most stalls. As before, not even the merest whiff of refrigeration anywhere. Imagine the fate of a butcher doing this in the chilly old UK. One of my local butcher’s barely survived having a little black kitten in his shop once a customer informed the authorities!
But, now the interesting one, and typical of a growing number of similar stalls.
Note the violet lighting washing over the meat stall
This marks a growing trend where violet lighting is being used for disinfection purposes, and began shortly after COVID-19 arrived. You may have seen numerous products on sale, ranging from toothbrush sanitisers all the way to really stuff like mobile phone sanitisers, and probably just about anything someday thinks they can people to buy.
There are a few problems, beginning with a simple rule that light follows – it only travels in straight lines, so anywhere it doesn’t shine is not sanitised.
But, more importantly, only UVC kills bad stuff – Germicidal UVC – short wave UV, which includes germicidal ultraviolet at 253.7 nm wavelength – is used for air, surface, and water disinfection.
UV-A – Long wave UV causes tanning and premature skin ageing.
UV-B – A small, but dangerous part of sunlight. Most solar UV-B is absorbed by the ozone layer. Prolonged exposure causes sun burn and may result in unhealthy effects on the skin and eyes.
Germicidal ultraviolet – UVC of 253.7 nanometres wavelength – kills germs, such as bacteria, viruses, mould, fungi and spores, that transmit infections, cause allergies, trigger asthma attacks or cause other unhealthy effects.
It destroys the DNA of these microbial contaminants, rendering them sterile. If microbes are irradiated with enough dosage germicidal UV, they can no longer reproduce and over time disappear from the indoor environment.
Sounds good – what’s the problem?
Simply that the scammers and con artists realised that UV light give off a lot of violet light, and that they can sell violet, or even blue lights, with the claim that they are UVC disinfectant types and, naturally, sell these at an inflated price compared to that charged for the non-UV visible light types.
There’s no way to tell just by looking that these are not producing UV, and most ordinary, non-tech or non-scientific people are conned by the sellers, who claim the presence of the violet or blue light ‘proves’ they are germicidal, and kill germs etc.
You can check for fluorescence under these lights, but unless you know the material being used to produce the fluorescent, that still doesn’t prove they are UVC.
Obviously, the sources producing only visible light DO NOTHING AT ALL, and the scammers could be killing, or at least making ill, people who trust and rely on such forged products as they may not take other precautions, so end up with MORE infection rather than less.
Not imagination
I know someone who buys these lights directly from China purely for the purpose of testing, to find out if the UV claim is genuine (he’s not even bothering to check that it is UVC) and, to date, has found most of them are bogus, and are made with cheap visible light only LEDs that produce an abundance of violet light, purely to make them look good to uneducated buyers. Yet they’re still being sold at the premium UVC price.