A frequently-cited NIH study shows that copper can render the novel coronavirus inactive within four hours - much quicker than most other building materials used for frequently touched surfaces. But is it quick enough?
A frequently-cited NIH study shows that copper can render the novel coronavirus inactive within four hours - much quicker than most other building materials used for frequently touched surfaces. But is it quick enough?

In the last couple months we've seen an uptick in announcements for new building products using copper, all of which purport that copper kills the novel coronavirus. Here are some recent examples:

  • Nana Wall has begun offering anti-microbial copper handles as an option for their opening glass wall systems.
  • Great Lakes Stainless offers a line of door push plates and copper covers for door pulls and emergency exit crash bars.
  • CuVerro is a copper alloy used for a wide variety of anti-microbial hardware and fixtures. Among the manufacturers using CuVerro in its product lines are Elkay, which offers a line of single-bowl, drop-in sinks, and Rocky Mountain Hardware, which offers a line of CuVerro door pulls and locksets, cabinet hardware, faucets, switch covers, and grab bars.
  • Copper Clean has introduced "antimicrobial surface patches" - copper stickers made to be applied on door handles, push plates, hand rails and other high-touch surfaces.
  • Proper Copper Design sells a selection of door and bath hardware, much of it manufactured from copper supply pipe and fittings that is nevertheless quite elegant.

Beyond building products, copper's all the rage now in a range of products that claim to keep people safe from coronavirus. According to a June 19, 2020 article in the New York Times, "there’s been a surge of interest in materials laced with the metal [copper], including socks, bedsheets and coatings that can be sprayed onto surfaces." The article points to atoms.com, which markets face coverings and masks with a built-in copper lining. Another company, CopperZap, reportedly offered a "nasal wand" it claimed could be touched to the hands, face and nostrils to protect against coronavirus. (This product is "currently unavailable," with no other information at the website; it's unclear if the site has shut down.)

Does copper work? Actually, yes, but with real limitations. Copper effects viruses in a number of ways: The metal damages the cell membranes, or "envelopes," of the virus; stresses the viral cells, creating hydrogen peroxide, which is toxic to the virus; and interferes with the proteins that keep the virus active.

An article by Martin Holladay in Green Building Advisor came out early (April 3) during the coronavirus outbreak touting copper as a wise choice for hand rails, door knobs and other building components that people touch frequently. This article points out some of the caveats with using copper as an antimicrobial: Clear coatings on copper, such as lacquer or varnish, will insulate the user from the antimicrobial and antiviral effects of copper. You want to strip these coatings off, and this means smooth copper surfaces will tarnish to the look of a dirty penny unless polished regularly. This tarnish, or even the green patina that untouched copper will eventually turn, does not reduce copper's ability to kill viruses and bacteria. (Hammered copper surfaces without a clear coat may be a smart way to get the antimicrobial effect and retain an acceptable finish without excessive maintenance.)

As best we know at this time, the novel coronavirus can live on copper surfaces for up to four hours.

But the crucial question, often smudged over or distorted, is how quickly can copper kill the virus? Some marketers lean on the assumption that the novel coronavirus behaves like other microbes, and suggests that copper kills the novel corona virus in "a matter of minutes" or "within an hour or two." That is false. As best we know at this time, the novel coronavirus (SARS-CoV-2) can live on copper surfaces for up to four hours, according to a study led by the National Institutes of Health. (For a summary of the research, which first appeared on April 16, see this NIH release.) This length of time is significantly better than the two to three days the virus remains active on stainless steel and plastic surfaces, but it's not as effective at limiting exposure to the novel coronavirus as some marketers suggest.

Most of copper's virus-killing abilities cited now by marketers are based on research with other viruses and microbes. When reviewing claims, check the dates on the research papers provided as "evidence" that copper kills the novel coronavirus. The "copper kills it" site that Great Lakes Stainless stood up to capitalize on the pandemic cites no research prior to 2015, long before the novel coronavirus surfaced. All it's claims are based on research addressing other types of viruses and microbes. Nana Wall is admirable in disclosing evidence based on current research stating that the novel coronavirus can live on copper up to four hours.

Bottom line: Certainly four hours is better than two to three days. But if you want to avoid contracting COVID-19 from virus-laden droplets on building surfaces, nothing yet can replace washing your hands frequently.

If you want to avoid contracting COVID-19 from virus-laden droplets on building surfaces, nothing yet can replace washing your hands frequently.

Keep in mind that the most common way COVID-19 spreads is from person-to-person contact, according to the CDC at this time. (Hence, social distancing or wearing a mask, along with frequent handwashing, remains the best way to limit exposure to the novel coronavirus.) Touching a surface or object that has the virus on it and then touching your mouth, nose, or eyes is not the main way the virus spreads, according to current health recommendations.