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Comment by msandford | Hacker News Reader

Germs don't get a chance to evolve resistance to this, at least as far as I can tell. At least not any more than humans have the opportunity to evolve a bullet defense.

The UVC doesn't disrupt their metabolism or mutate their genetics subtly, it shreds their chemical bonds.

It's much more like worrying that germs will evolve resistance to hydrogen peroxide or ethanol or iodine disinfectants. It's not impossible of course, but it'll require the kinds of mutations that make them entirely other organisms.

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> The UVC doesn't disrupt their metabolism or mutate their genetics subtly, it shreds their chemical bonds.

But it does -- this only depends on an prompt dose, at which you have exactly one chance. How can you guarantee a lethal dose (for any definition of lethal) for every single microorganism? Even hard gamma was adapted for, compared to that UV is nothing.

I guess I don't follow your reasoning. You don't have to kill all of them, you just need to ensure all that get a dose die. If some dodge the death rays, that's ok.

Antibiotic resistance is a thing not because antibiotics are a molecular shredder that chews up the bugs. It's because they're some kind of metabolic poison.

I might be able to increase my resistance to Iocaine powder by slowly dosing up. But I can't increase my resistance to Andre the Giant tearing me limb from limb.

> you just need to ensure all that get a dose die.

I believe they were asking specifically that. How do you ensure that?

In other words, how do you ensure all get the correct (lethal) dose?

Some may be partially hit. It would be very hard to tell, no?

I believe that the way you do this is protocol and dosing.

If you put these in ductwork then you need to look at the flow rate through the duct and the required light flux and then ensure that the supplied flux is well in excess of that.

Remember we're not talking about your normal LD50 toxicity. It doesn't kill by metabolic disruption. It kills by turning the thing from organism into not organism.

If an organism survives it does so not by adapting its metabolism to the poison. It does so by enough of itself not being destroyed that it is able to rebuild.

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