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Comment by radarsat1 | Hacker News Reader

Does anyone know if there's any truth to ideas that certain metals like copper are "antibacterial"?

I am worried because I have seen stories (e.g. [1]) that claim that masks incorporating copper can be effective against the virus (never mind that "antibacterial" apparently also means it can fight viruses, which makes no sense). Basically, I am seeing an increase in people selling "masks" that are not approved and that has me worried. I would like some information about whether there is any science, for or against, to the idea that particular materials, especially metals, have any kind of "special" effect against bacteria and viruses.

[1] https://www.efe.com/efe/america/sociedad/mascarillas-de-cobr... (spanish)

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The proper name is the oligodynamic effect [1], and that seems well-proven to me at least but I'm certainly no expert. It seems the effect does cover viruses too, and copper has such an effect [2].

[1]: https://en.wikipedia.org/wiki/Oligodynamic_effect [2]: https://en.wikipedia.org/wiki/Antimicrobial_properties_of_co...

Don't be lazy. Just Google search SARS-CoV-2 on surfaces and you will see that Coronavirus lasts about 4hrs in Copper, while it can stay one day in Cardboard and several days in Stainless Steel and Plastics.

So, yes, there is something special about copper. But copper is not a virus killer (i.e. kills them at contact), it justs seems that viruses don't survive that long in copper. This has been known since ancient times (where Copper pantry and utensils was preferred over Steel).

The New England Journal of Medicine. The scientists found that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was detectable in aerosols for up to three hours, up to four hours on copper, up to 24 hours on cardboard and up to two to three days on plastic and stainless steel.

https://www.nih.gov/news-events/news-releases/new-coronaviru...

The anti-microbial effect of copper has been known for decades, which is why it fathoms next that fixtures in hospitals are still made from steel.

Millennia, actually. There is clear evidence that people understood the medical importance of copper in ancient Rome, and even some evidence of Bronze-age Egypt and ancient India (which is to say it's clear copper was used in medicine, but it's unclear people had evidence it helped). That's 2000 years definitely, and 5000 years possibly.

Prior to disinfectants, hospitals used a lot of copper. It only became a relic with industrial-grade disinfectants.

That said, the timelines aren't such that it seems useful for use in masks. Viruses and bacteria survive on copper for hours, instead of days. There are a lot of uses of copper which aren't grounded in science and make no sense (superstitious nonsense).

But copper for things people touch a lot? Doorknobs? Definitely makes sense.

It's simply that copper is too expensive to use on an extensive scale such as hospital fittings.

Copper costs about twice as much as stainless steel per tonne and that is with current demand levels. Squeezing supply would raise that significantly.

Annual worldwide copper production is 18M tonnes and increasing. Most of it is used in plumbing and wiring. Taking a little bit for hospital hardware wouldn't impact demand much, and the extra cost would be a rounding error compared to all of the other equipment that goes into a modern healthcare facility.

> Don't be lazy.

Thanks, your answer was very helpful. However, I feel you could have given it without this prefix, without any detriment to the content of your post.

Here's an interesting reference (viruses): https://www.sciencedirect.com/science/article/pii/S030438941...

And more generally (bacteria): https://en.wikipedia.org/wiki/Antimicrobial_copper-alloy_tou...

EDIT: https://en.wikipedia.org/wiki/Antimicrobial_properties_of_co...

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