S.O.S! Could UV Light Disinfection Help Save us All From Covigeddon?
Author Stephen Bieda
Although it has been known since 1878 that UV light can deactivate microorganisms, important recent data has emerged about how UV light works and how a certain part of the UVc spectrum may one day prove to again be Nobel Prize in physics worthy stuff. As a mobility industry tech wonk, I have shifted part of my spare time from electric vehicle (EV) research and analysis to photobiology and photochemistry. Why? Well initially it was because I realized that it’s pretty hard to sell an EV if customers are fearful of coming to your service centre or showroom due to COVID19 exposure. Soon after, I realized that maybe I could help in some way to mitigate “Covigeddon” through knowledge sharing. It is a fascinating area of research with immense implications for the entire built environment and the mobility industry in all it’s forms. So here is what I have learned about UVc light and how it might apply in a mobility industry context and far beyond.
UV light if applied in sufficient dosages destroys DNA, but it is also known that UVc is carcinogenic and catarogenic. This means it causes cancer and cataracts. There is however a very broad range of UV light wavelengths with different properties. In this article, I am focused on UVc emissions in the 200–280 nm part of the UV spectrum and more interestingly on the 200–230nm shorter wavelength known as Far UVC.
So in the wake of the COVID19 pandemic, I believe what this will mean to taxi and Uber drivers for example, is that very soon they will be required to prove that their car has been properly disinfected and not just with wipes or germicidal sprays, but with UV light as well. The problem with germicidal UVc light inside a car is that people must exit the car and it takes time for a sufficient dose of light photons to hit a surface at a effective level. If that surface is not flat or if it is a shadowy environment, then the germ killing photons can’t deactivate DNA as efficiently, or not at all in some nooks and crannies. So for an effective UVc disinfection system to be incorporated into a car interior (with or without people present) multiple emission sources will likely be required. All this of course is bad news for shared mobility drivers and passengers alike who need people to be able to move in and out quickly to make room for the next customer. If it takes several minutes or hours to disinfect a car between passengers, then costs rise and delays occur.
For public transit this is an exponentially greater problem of course, which is why companies like Dimer UVc with their GermFalcon disinfection carts are popping up to disinfect airplane cabins. So before autonomous vehicles even get into the public realm, it would seem very likely that they will all require self-disinfecting technology to be a direct from the factory built-in interior feature.
What UVc light does to a microorganism’s DNA if applied in sufficient dosage is stop them from replicating. For this to happen a particular dosage of germicidal UVc light must contact a surface for a known period of time (inverse square law). With the coronavirus for example, the reported known dose of UVc with the popular 254 nm wavelength is 40mJ/cm2 on a flat surface. With Far UVc 222 nm the dosage required to deactivate COVID19 viruses even lower according to a company called Far-UV Sterilray led by brothers John Neister CEO and physicist COO Edward Neister have been conducting research in the Far UVc realm since 1999. The later brother holds multiple related Far-UV patents starting in 2006 and he cites that 2 mJ/cm2 is sufficient for coronavirus log kill. One of the key product differentiators that Far-UV Sterilray claims their technology offers is the ability to provide skin safe 222 nm light without the need for a bandpass filter unlike their competitors at Ushio. Bandpass filters are like a camera lens filter which stops higher and lower wavelengths of UVc from being emitted. Far-UV Sterilray also reports a 10x longer bulb life of 30,000 hours in a hospital HVAC system that they have been doing testing at for years.
What has now been proven in multiple clinical studies is that Far UVc 222 nm does not cause cancer or cataracts unlike like higher UVc wavelengths. Kobe University came out with a key study on Far UVc effects that could be ground breaking in combating the COVID19 pandemic. They tested a relatively obscure UV wavelength of 207 nm UVC which was first studied in October 2013 by Dr David Brenner of Columbia University’s Center for Radiological Research (CRR) team. Brenner et al showed the promise of limiting the spread of coronavirus, as well as more familiar viruses like influenza and measles with Far UVc light. Inventors Gerhard Randers-Pehrson, David Jonathan Brenner and Alan Bigelow of Columbia University reference “UV radiation at approximately 207 nm to 220 nm” in their patent filings. The Columbia U research team launched a crowdsource funding campaign to raise money for further research “to test the use of a new UV-light technology to limit the spread of airborne viruses”.
Far UVc technology could conceivably have a huge impact on reducing our need for prescription medicine. If human safe Far UVc light could potentially be beamed ubiquitously from light fixtures at airports, bus stations, schools, sports stadiums, theatres, homes etc, then we could provide an incredibly powerful way to kill pathogens before they spread and greatly reduce the need for drugs and hospitalization due to contagious illness. So might Far UVc 222 nm technology one day warrant yet another Nobel Prize in physics for UV light?
Unlike other parts of the UVc spectrum between 200–280 nm, Far UVc 222 nm has recognized with mounting evidence, to be safe for human skin and eyes. So this wavelength is ideally suited for all public spaces WITH people present, including spaces like your own car. What I have found however is that there are no long term human clinical studies out yet to determine what other effects (other than skin cancer) that such exposure to 222 nm UVc light may have. One possible concern is, that while Far UVc 222 nm light is sure to kill pathogens over time and at some distance at least in mice, it is also likely that some good microbiomes that live on our skin and throughout spaces, will also likely be killed leading to possible unintended consequences. In my tweets with Dr. Eddie Fatakhov a Best-selling Author, Nutritionist, and Board Certified Internist who has been interviewed widely on COVID19 and Far-UVc technology, he explains that the trillions of microbiomes on our skin reproduce extremely fast and since most of our skin is covered with clothing most of the time the impact on microbiomes would be relatively small.
Given the dire economic nature the world is in with the COVID19 pandemic however, it is not surprising that Far UVc 222 nm technology has come to market faster than expected just as vaccines have in the December 2020. If you think about the job creation that the transition from incandescent and fluorescent lights to LED lights created, imagine what retrofitting buildings and public transit with a safe Far UVc 222 nm light could do.
A presentation of the peer reviewed clinical trials on Far UVc 222 nm impact on mice was reported by scientists at the American Society of Photobiology meeting in Chicago on June 28, 2020. The Japanese UVc light manufacturing multi-national Ushio, was a partner in the Kobe Far UVc mice study and is working on the mass production of various 222 nm excimer (short for excited dimer) light products. While Far UV Sterilray and Ushio use krypton chloride-based excimer bulb technology, there has been very recent news from NS Nanotech in association with University of Michigan and McGill University showcasing new solid state Far UVc 222nm emitters that will be shipping mid 2021 at prices in the $199 range.
It should also be stated that although ubiquitous safe UV light disinfection is potentially massively disruptive, a multi-pronged disinfection approach to built environments will always be required in order to minimize the risk that a pathogen can mutate and evolve. Here are a list of suggested best practices:
- Practice good personal hygiene.
- Germicidal chemical usage on certain surfaces where shadowing is a problem with 60+% alcohol or a product such as Bioesque with Thymox.
- A range of UV light disinfection for different applications (222 nm, 254 nm and even 405 nm in some applications).
- Use of different anti-microbial surface products such as silver and copper-plating.
- Use of dry steam vapor disinfection particularly for rough surfaces and fabric car interiors. (*Note: Steam cleaning ≠Steam vapor nano crystal disinfection, see www.advap.com)
“However, microorganisms, particularly bacteria, may easily evolve resistance to UVA and UVB light exposure [153]. UVC light to control microbial growth has recently gained popularity because there is no a priori resistance to it, as it does not penetrate the atmosphere. While effective [155], it is logical to predict that resistance to UVC might develop over time with increased exposure.” — 15 July 2019 Journal of Exposure Science and Environmental Epidemiology
Lastly, since it is widely known that UV light damages plastic and other surfaces over time, I did ask a leading auto interior supplier about the potential impact of UV light on the interior of your car. The estimate was conveyed in this example, “with UV light disinfection utilized in your car (not Far-UVc 222 nm), research shows that a 10 year old interior might look like it is 11 years old”. Conversely, Far-UV Sterilray reports that 222 nm wavelength does not cause damage to plastic or skin. So is this a level of risk most people will be willing to take even without the hindsight of this pandemic? I think so. Might other more critical unintended and/or unforeseen health risks of Far UVc 222 nm be worth the gamble? We might soon find out.
References
Repetitive irradiation with 222nm UVC shown to be non-carcinogenic & safe for sterilizing human skin
Far-UVC light: A new tool to control the spread of airborne-mediated microbial diseases
