Common Threads: Media, Science, Technology, and Other Magic

Sunlight is the Best Disinfectant

United States Supreme Court Justice Louis Brandeis (1856-1941) wrote in a series of articles for Harper’s Weekly (collected and published in 1914 as a book titled Other People’s Money—and How the Bankers Use It, now available online in its entirety):

“Publicity is justly commended as a remedy for social and industrial diseases. Sunlight is said to be the best of disinfectants; electric light the most efficient policeman.”

At the time, this was a metaphor for combating corruption by demanding transparency in finance and in government.

Brandeis may have simply condensed, modernized, and popularized a James Bryce (1838-1922) statement from his 1888 book The American Commonwealth:

“Public opinion is a sort of atmosphere, fresh, keen, and full of sunlight, like that of American cities, and this sunlight kills many of those noxious germs which are hatched where politicians congregate. That which, varying a once famous phrase, we may call the genius of universal publicity, has some disagreeable results, but the wholesome ones are greater and more numerous. Selfishness, injustice, cruelty, tricks, and jobs of all sorts shun the light; to expose them is to defeat them. No serious evils, no rankling sore in the body politic, can remain concealed, and when disclosed, it is half destroyed.”

Behind the metaphor there is, of course, sound science behind the advocacy of sunlight as a disinfectant.

As the global COVID-19 pandemic reached the United States, in early March 2020 a friend and former client contacted me and asked some rather good questions about the possibility of preventing the disease by using ultraviolet light-emitting diodes (LEDs) instead of respiratory filter masks, which were becoming scarce.

My background is in researching and developing electronic industrial and consumer products, and I have done some innovative work with power systems that are battery-operated. I also have some recent experience contributing to the development of a medical device, and have gained familiarity with regulatory challenges in that area.

I documented the results of my research in a feasibility study. In short, I reported:

1. In the United States, products that are intended to diagnose, treat, cure, or prevent disease are regulated for safety and efficacy by the Food and Drug Administration (FDA); FDA would have regulatory jurisdiction for the proposed disease-preventing device.
   • The efficacy of ultraviolet germicidal irradiation (UVGI) is well established, dating back to 1878 and yielding a of Nobel Prize for Medicine in 1903.
   • For the subtypes of ultraviolet (UV) light used for UVGI (short-wave, “hard”, or “deep” UV, classified as ultraviolet C, or UVC, with wavelengths of 100-280 nm) and typical germicidal lamps (with peak emission at 254 nm), human exposure is unsafe, causing skin cancer and cataracts; further, H Lyman-α UV (hydrogen Lyman-alpha UV, at 121-122 nm) includes the approximate boundary to ionizing radiation, exposure to which “causes damage to living tissue, and can result in radiation burns, cell damage, radiation sickness, cancer, and death”.
   • Although a 2017 study identified a wavelength window in the far-UVC region (from 200–222 nm) that inactivates bacteria efficiently and is not harmful to mammalian cells, it did not appear to address efficacy with viruses.
2. Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 or “SARS virus 2”, identified earlier as 2019-nCoV).
   • With SARS-CoV-2 so new, information about it is limited.
   • SARS-CoV-2 appears to be similar to the 2002 SARS-CoV.
   • Prolonged UV irradiation reduced the infectivity of the 2002 SARS-CoV, but did not fully eliminate the virus (NIH).
3. At respiration rates, relying upon only UV to inactivate SARS-CoV-2 from inhaled air would be impractical (expensive, ineffective, and/or immobile).

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