So, “powerful” as Trump’s latest ideas on coronavirus treatment are, there is a surprising nugget of wisdom to the following:
A question that probably some of you are thinking of if you’re totally into that world, which I find to be very interesting. So, supposing we hit the body with a tremendous, whether it’s ultraviolet or just very powerful light, and I think you said that hasn’t been checked, but you’re going to test it. And then I said supposing you brought the light inside the body, which you can do either through the skin or in some other way. And I think you said you’re going to test that too. Sounds interesting, right?
Back in March 18, rationalist thinkers Roko Mijic (yes, he of the Basilisk) and Alexey Turchin explored the idea of using “ubiquitous far-ultraviolet light” to “control the spread of COVID-19 and other pandemics” at LessWrong.
Inspired by a related paper from 2018 (Welch, David, Manuela Buonanno, Veljko Grilj, Igor Shuryak, Connor Crickmore, Alan W. Bigelow, Gerhard Randers-Pehrson, Gary W. Johnson, and David J. Brenner. 2018. “Far-UVC Light: A New Tool to Control the Spread of Airborne-Mediated Microbial Diseases.” Scientific Reports 8 (1): 2752), they point out that normal UV light has already long been used for sterilization purposes:
One of the most promising and neglected ideas for combating the spread of covid-19 is the use of ubiquitous ultraviolet light in our built environment (trains, offices, hospitals, etc). Ultraviolet light is already being used as a disinfecting agent across the world; it goes by the acronym UVGI – “Ultraviolet germicidal irradiation”. The energetic photons of UVC light break chemical bonds in DNA and kill/inactivate both viruses and bacteria.
Furthermore, Far-UVC light is highly effective at killing both viruses and bacteria with modest inputs of energy, while humans remain safe since it can’t penetrate the thin layer of dead skin on our bodies.
The amount of Far-UVC energy required to kill 99% of the viral particles is estimated to be around 20J/m^2. With a power of, say 5W/m^2, a system would need 4 seconds to mostly sterilize a viral aerosol that could travel from person to person. However a lower power system would still have some benefits – we know that people can be infected by air that was contaminated 30 minutes earlier. Higher power in these wavelengths could be difficult to achieve with Kr-Cl Excimer Lamps as the overall efficiency from electricity to Far-UVC is ~10%. AlN Far-UVC LEDs would likely have a much higher conversion efficiency.
The obvious locus of usage would be indoors, since the outdoors, by definition, receive some UV light – especially during sunny weather, which may explain why the coronavirus progresses slower in southern countries. Moreover, the indoors are where the vast bulk of infections happen anyway. I would note that according to a recent study, only a single one out of 318 outbreaks in China occurred out-of-doors (Qian, Hua, Te Miao, L. I. U. Li, Xiaohong Zheng, Danting Luo, and Yuguo Li. 2020. “Indoor Transmission of SARS-CoV-2.” medRxiv, April, 2020.04.04.20053058). So making indoor spaces much safer may well lower r0 to substantially less than 1 even with no other mitigating policies.
The authors are skeptical about our capacity to launch Far-UVC lighting projects: “such a project would at best be ready by the start of 2021 (and then only with wartime levels of effort and purpose“. However, via the Pareto Principle, wouldn’t bathing just a few of the most crowded and high passenger load areas in Far-UVC light be sufficient to derive most of the benefits anyway? I am thinking primarily of major public transportation nodes, such as metro systems and bus stations. Further down the line, costs can also be affrayed by making it the responsibility of small businesses, such as shops and restaurants, to install these systems; they would surely prefer that to having to undergo repeated closures from cyclical lockdowns. Meanwhile, the marginal benefits to installing them in places such as elevators would presumably be much smaller. (PS. Though you should avoid using elevators in principle right now – it’s good for you, anyway).
Finally, there is also a great deal of potential for integrating Far-UVC lamps with AI systems to cut down on energy use and make them more safer, such as only having them light up when there are few or no people. Even more ambitious ideas might involve hooking them up to geolocation and CCTV/facial recognition systems, with initially scarce Far-UVC resources being deployed to areas that were recently “polluted” by an identified carrier.
As it becomes increasingly clear that the current lockdowns will fail to contain the epidemic within the modest amount of time left before economic pressure and populist demands force an end to them, it is an idea that we need to start actively exploring and implementing now – if not the day before yesterday.