A few days ago, the US Environmental Protection Agency (EPA) approved the use of copper and copper alloy surfaces to help prevent the spread of COVID-19 (hat tip to K10 on Twitter). The use of copper alloys is an ancient technology that requires less energy to produce than steel and is highly recyclable, making this not only a good technology for germs, but for the environment.
“Providing Americans with new tools and information to fight the virus that causes COVID-19 is one of EPA’s top priorities,” said Acting Assistant Administrator for EPA’s Office of Chemical Safety and Pollution Prevention Michal Freedhoff. “Today’s action marks another step forward in EPA’s efforts to listen to the science and provide effective tools to help protect human health.”
Companies wanting to make the claim that a product has health benefits go through the EPA and other government agencies, submitting proof of the effectiveness of the product to actually provide the advertised benefit. In this case, the Copper Development Association provided proof of testing that shows 99.9% of viruses that were harder to kill than COVID-19 are rendered inert within two hours of sitting on the surface. With this approval, it’s legally safer to advertise copper-coated products or products made from the right copper alloys as having a health benefit.
The only catch here is that the alloys have to be 95.6% copper, which will limit their usefulness, as copper is very malleable unless mixed into an alloy with more tin (making bronze) or zinc (making brass). For products that don’t take a lot of force, like doorknobs, high-copper blends will work. Also, many surfaces can be coated with high-copper alloys, allowing them to get the benefit of the alloy on the surface, with the strength of other materials underneath to get the desired structural strength needed.
This isn’t the first time we’ve seen the cleantech community show an interest in this technology to stop the spreading of germs. One example is Twitter user @CafeElectric, who made his own copper-covered door handles for a Tesla Model S.
— Otmar (@CafeElectric) March 26, 2020
How Copper Kills Viruses
Smithsonian Magazine has a great article covering the way copper surfaces kill viruses and bacteria. Bill Keevil, a microbiology researcher in England, gave them a lot of information about how this all works.
“One of the ironies is, people [install] stainless steel because it seems clean and in a way, it is,” Keevil told them. “But then the argument is how often do you clean? We don’t clean often enough.”
That’s the great thing about copper surfaces. On glass, plastic, and steel, deadly viruses and bacteria, including antibiotic strains like MRSA, can survive for days and still infect people. Copper, due to its unique properties, kills these deadly germs just by being there. The EPA warned in its press release that copper surfaces are no substitute for cleaning, masks, and social distancing, but they do help reduce the chance of missing germs on a surface.
Copper kills germs because it has an extra electron it its atomic makeup, in the outermost orbit. This electron reacts with things that land on it, killing the germs quickly. Ions blast apart bacterial cell membranes and the coatings that protect viruses, rendering them inert. Most viruses and bacteria succumb within minutes, but COVID’s stubbornness only buys it some extra time. It, too eventually dies.
Scientists who talked with Smithsonian Magazine say that the antiviral properties of copper surfaces never wear off. Even surfaces that have been in use and regularly touched by people for 100 years are still killing germs. Railings at New York City’s Grand Central terminal, despite their age, are still killing germs just like they did when new.
The knowledge of working with copper and its alloys goes back at least 7,000 years. We have no idea who did it first because that kind of metalworking predates writing by at least 2,500 years. Ancient societies also knew that copper healed various infections, but they didn’t know why. They just knew that copper worked against diarrhea and even cuts on the battlefield.
The reason prehistoric people were able to work with copper was its low energy use. Without modern technologies like the Bessemer process, blast furnaces, and arc welding, steel was largely out of reach except for some limited applications starting 3,000 years later. You just don’t need to get a fire as hot to melt and shape copper or to mix it with other metals to create alloys like bronze or brass. We even look at that part of ancient history as the Bronze Age, because it marked a departure from the Stone Ages.
The only reason copper alloys fell to iron and steel was hardness and durability for many applications, like swords. Buildings and automobiles are largely possible due to newer metals. That doesn’t mean copper ever went away, obviously. For electrical conductors, ornamental use, and for antimicrobial surfaces, copper and its alloys are still extremely useful.
Today, with the industrial revolution and concerns about climate change, we are now back to looking for low-energy ways of doing things. New technologies like lithium-ion batteries are more exciting, but sometimes just looking to the past for more energy efficiency is a good move. The less energy we use working metals, the less the environmental impact.
Thus, if copper coatings and objects like doorknobs started being made out of copper alloys more than they are today, we would see a net improvement in environmental impact.
Low energy isn’t the only thing copper alloys have going for them. According to an older article by the Copper Development Association, it’s also highly recyclable and gets recycled a lot. Copper alloys maintain their physical properties even when melted down to make new things, so there’s a lot less refuse. Also, the cost of copper makes it very unlikely anyone would intentionally throw it away, so it almost always gets recycled.
I’ve seen people go into abandoned vehicles looking for copper to steal, and at dumps, you see employees looking for any metal going into the garbage, and try to pull it out for the dump to sell to recyclers, thus saving the operation money.
Given the low energy requirements, ease of recycling, and the fact that it almost always gets recycled, it’s a very environmentally friendly material, especially in the long run. While not new or particularly innovative, seeing more widespread use is something cleantech enthusiasts should definitely encourage.