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‘Self-Cleaning’ Surfaces Are Not, but That Doesn’t Make Them Useless

The issue with self-cleaning solutions is branding

Button and door handles are the most touched objects in any building, making them the target of hygiene efforts driven into overdrive by the ongoing global pandemic. From ancient allow to new transparent sheets, new technology claiming to offer self-cleaning touchpoints may make our buildings safer but they won’t help much with COVID-19. 

Self-cleaning materials have been around for centuries. Brass is naturally self-cleaning thanks to the oligodynamic effect. Brass can trace its roots as a metal alloy back to 3,000 B.C., the ancient Indian medical text Sushruta Samhita dating back to the 12th century promoted the use of specific metals for surgical producers. It wasn’t until the 19 Century that scientist Carl Nägeli first formally identified brass’ disinfecting properties. Small amounts of some heavy metals are deadly to bacteria but harmless to humans. Scientific understanding is still evolving but its thought that heavy metal ions cause membrane damage to bacteria by impacting proteins in the cell wall, rendering them inactive. Copper is the only product with residual claims against viruses to be registered for use nationwide by the EPA. 

“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.”

The problem is cooper is prohibitively expensive considering how many touchpoints there are in a building. Self-cleaning coatings offer more cost-effective options. Applied as a film substrate, self-cleaning material works by oxidizing organic compounds at the microscopic level. Titanium dioxide in the film acts as a photocatalyst when activated by light, producing Hydroxlyu radicals, a substance with twice as much oxidizing power as bleach. The oxidation process breaks down compounds into harmless byproducts. Self-cleaning material isn’t removing the containment, just lowering its risk. Titanium dioxide is cheap, chemically inert without light, easy to handle, easy to turn into thin films, and is already established as a safe household product, using in cosmetics, paints, and foods. 

Nantouch Materials sells green, self-cleaning films using titanium dioxide oxidization that can be used practically anywhere. The thin sheet of material can be wrapped on door handles, doormats, and buttons. Nanotech claims the product has been tested extensively by independent, EPA, FDA and GLP compliant laboratories. Working with CBRE, Marriott and the U.S. Navy, Nanotouch has been installed on 10 million surfaces. The product was awarded the 2021 Vision Award by 

“Earning the stamp of approval from the judges that are experts in their own right validates the trust thousands of facility managers and others across the globe have put into our surfaces to create cleaner, safer environments for all,’ Nanotouch co-founder Dennis Hackemeyer said. 

Whether Nanotuch works as a surface disinfectant is beside the point when it comes to the coronavirus pandemic. Nearly two years into this outbreak we know that COVID-19 rarely spreads through surfaces. The CDC has gone so far as to say surface transmission is “not thought to be the main way the virus spreads.” Self-cleaning door handles and buttons have the potential to make our buildings safer, airborne diseases aren’t the only diseases, but they must not get wrapped up in the same hygiene theater taking place across the globe. Self-cleaning products still have to be cleaned. 

Self-cleaning products often give way to a false sense of security. Some studies have shown anti-microbial surfaces in high-touch areas are associated with higher microbial burdens than other types of hardware. Researchers speculated that antimicrobial surfaces may increase the use of hardware and decrease the frequency of cleaning. The issue with heavy metals and oxidation alike is that the process is not instant, disinfection can take minutes, sometimes hours. They may be effective measures, but they’re passive. Fighting infections requires more active solutions, almost all revolve around good ‘ol elbow grease. Nanotouch recommends replacing its products regularly with non-abrasive cleaners and replacing each touchpoint skins every 90 days or sooner in higher traffic areas. 

“Typically, there is not enough time between touches for copper to kill a significant portion of bacteria on that surface,” Healthcare Surface Consulting President Linda Lybert wrote. “So the potential to spread bacteria is very real. If someone assumes they do not have to clean a copper surface, can you imagine what would happen over time?”

The science is still evolving, but self-cleaning solutions have potential in viral mitigation. The big issue may be the branding. They’re not ‘self-cleaning’ at all, dubbing them as such promotes the type of false security that the material is working against. Calling them anti-microbial surfaces or bacteria-resistant is more apt, creating a better sense of the value proposition for facilities managers to understand. 

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