How does UV light sanitize surfaces?


How does UV light sanitize surfaces?

In: Chemistry

UV light has a lot of energy per photon. Enough energy to knock electrons off many common chemicals that make up living things bodies. Once that happens you have what’s called a free radical, they like to react with anything they are near. It can also break bonds in chemicals necessary for life. So UV creates free radicals that go around and wreck the complex web of chemical reactions we call life. They are capable of screwing up most pathogens so badly that they just die. Every living thing can take a certain amount of UV but eventually it’s just too much for their system.

UV light is a short enough wave length that it can penetrate into cells/viruses. When it does, it causes damage to the pathogen’s DNA. Essentially it gives pathogens supercharged cancer. It damages bacterial/viral DNA so badly that the cell can’t replicate and dies. Which is why most UV sterilization protocols are a minimum of 15 minutes, sometimes up to an hour, to make sure enough damage is done.

The same way it can cause us cancer – it mutates DNA.

In humans we have a LOT of DNA and a lot of cells, so if DNA gets mutated in a cell and not repaired, it’s unlikely to kill us – it’s probably not going to be in an important region of our genome and even if it is if we need to we could destroy the cell and have plenty of others to take over for it.

Bacteria have less DNA and are unicellular, so a mutation is more likely to be lethal

Not a biologist but I do want to chime in that the optimal wavelengths for disinfection are close to 270 nm and are commonly produced by a mercury-vapor lamp. That I have seen, no LED can produce this frequency. Please don’t fall victim to LED sanitation devices.

UV light creates free radicals (they basically destabilize certain molecules) which will then go around and react with things. It may react with DNA and pull electrons off it. When it does that the DNA can physically kink or take on a conformation that makes DNA replication errors more common. When the DNA replication machinery comes around, it may a hard time replicating on a kink and may ‘stutter’ and insert the wrong nucleotide, which just amplifies the DNA damage in the form of mutation going on. If DNA is damaged extensively, cells may even commit suicide. That’s what a sunburn is, damaged skin cells taking one for the team so they don’t pass on crappy mutated genes that might turn into cancer.

That being said, it takes a lot of UV to damage something to that point and most UV sanitation wands are kind of a scam because just waving them around won’t expose microbes to enough UV radiation to actually kill most of them.

Uv rays damages dna, your cells have ways to cope and your body has ways of getting rid of cells that can’t so uv is cool for you. Most germs do not have this

So at my hospital we have these machines that you put touchscreen devices in to sanitize. They are slid into a mirrored box with 6 UV bulbs for about 1 minute. Is that enough to actually accomplish anything? The device automatically ends this cycle after 1 minute so we dont choose the length of time.

If you have a spare 20 minutes, Big Clive on YouTube really digs into it.

More specifically uv light causes two structures within the DNA to bond – more or less throwing a wrench in molecular machinery that reads it.

Would it be worth it to lay your groceries out in the sun before bringing them into your house if you needed to be buying essentials right now? Is that how it works? Or am I being dumb?