Biosecurity Poland
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Kaja Turzańska

The light that could change the fate of future pandemics

In the 21st century, light may let us stop breathing in each other’s diseases. It sounds like science fiction, but a technology capable of inactivating airborne viruses and bacteria has existed for decades: UV-C, short-wavelength ultraviolet light. Hospitals have used it for years. The problem was that conventional UV-C is also dangerous to people1.

Only recently has something new held out promise: far-UV-C, especially light at a wavelength of around 222 nm, which could potentially kill pathogens without damaging the skin and eyes of people in the room2.

If this technology really does prove safe and effective at scale, it could change the architecture of buildings, public transport, schools and hospitals as fundamentally as air conditioning or HEPA filters did1.

But today far-UV-C is in a strange phase:

  • too promising to ignore,
  • too uncertain to deploy everywhere.

A problem we hardly treat as infrastructure. COVID-19 reminded the world of something epidemiologists had long known: indoor air is a medium for disease transmission. For most of architectural history we have designed buildings for temperature, humidity, energy costs and acoustic comfort, and almost never for the “microbiological cleanliness of the air”3. That is rather absurd. Drinking water is filtered, chlorinated and continuously monitored. Meanwhile the air in schools, offices and restaurants is often a shared biological aerosol with no active disinfection at all.

This is where UVGI — ultraviolet germicidal irradiation — comes in.

UVGI is not new. As early as the 1930s, “upper-room UV” was in use: UV lamps mounted high near the ceiling that disinfected the upper layer of air. The technology was effective against tuberculosis, among other diseases. Conventional UV-C lamps emit light at around 254 nm. This wavelength is very effective at destroying the DNA and RNA of microorganisms. The problem is simple: it also destroys human tissue.

That is why traditional UVGI requires:

  • empty rooms,
  • shielding,
  • ceiling-level installation,
  • strict safety procedures.

It works, but it is inconvenient and hard to deploy at scale4.

Why could 222 nm be a breakthrough?

Far-UV-C rests on the seemingly paradoxical idea that a shorter wavelength can be safer. Usually this means 222 nm light generated by krypton-chloride (KrCl) excimer lamps. The hypothesis is as follows. Light at 254 nm penetrates the living cells of the skin and eye, but 222 nm is absorbed very superficially, so it does not reach the living layers of tissue, while still effectively destroying bacteria and viruses, which are much smaller. In practice this would make continuous disinfection of the air possible while people are present2. That would be an enormous leap for civilisation.

Imagine schools that continuously inactivate viruses, metro systems that limit the spread of flu, hospitals with radically fewer hospital-acquired infections, airports operating like a “sterile airflow”.

That is why scientists are both excited and cautious. The problem is that “seems safe” is not the same as “is safe over 30 years of population-wide exposure”.

Research so far is promising. Effectiveness against bacteria and viruses has been demonstrated; many experiments have shown no significant skin damage, and a growing body of data suggests no serious eye damage at controlled doses5. But there are important caveats.

1. The filter problem

222 nm lamps do not emit perfectly “pure” 222 nm light. They can also emit longer UV wavelengths, which are biologically more hazardous. That is why optical filters are crucial. Studies have shown that the quality of filtering dramatically affects the safety of the system. This means cheap equipment can be risky, and regulations must be very precise6.

2. The long-term safety problem

The biggest question is: what happens after 10, 20 or 30 years of exposure? Even if a single dose looks safe, public health demands enormous caution. Carcinogenic or ophthalmic effects can appear years later2.

3. The “last mile” problem

Even if the technology works in the lab, deployment in real buildings is harder. What matters: room geometry, air movement, shadows, dust, lamp maintenance, ceiling height, energy costs and human exposure7.

Far-UV-C is not a magic force field. It is rather another layer of air-quality infrastructure.

The biggest problem: no institutional owner. One of the most fascinating aspects of far-UV-C is that the technology does not fit existing structures. Who should deploy it? Epidemiologists, architects, HVAC engineers, occupational health and safety, radiation regulators, or perhaps lighting manufacturers?

The result is classic for a “technology between categories”: everyone is partly responsible, so no one is truly responsible.

COVID-19 briefly increased interest in air quality, but most countries returned to the status quo: a few filters, a few CO₂ monitors, very few lasting changes to infrastructure. And yet the potential is huge. If far-UV-C proves safe and economical, the effects could reach far beyond pandemics8.

Potential effects:

  • less seasonal flu,
  • fewer school absences,
  • fewer hospital infections,
  • lower risk of future pandemics,
  • more resilient public infrastructure.

This could be one of those technologies that become “boring” precisely because they work, just as hardly anyone gets excited about water chlorination today, even though it has saved millions of lives9. The history of technology suggests two possible scenarios for UV-C lamps.

Scenario 1: “Another technology that got stuck”

Far-UV-C could get bogged down in regulation, costs, biological uncertainty, a lack of standards and weak post-pandemic demand. It would then remain a niche solution for hospitals and laboratories.

Scenario 2: “The invisible infrastructure of the future”

But it is also possible that in 20 years far-UV-C lamps will be standard in new buildings, schools will have “air sterilisation” as taken-for-granted as ventilation, and the transmission of seasonal diseases will fall dramatically. And most people won’t even know they are sitting under light that kills viruses.

The most interesting question is not “does it work?”, because a growing number of publications indicate that it does. The question is rather whether societies can build infrastructure against threats that are invisible, and do so effectively.

It is a very difficult kind of political investment. Success would mean that “nothing happened”. The costs would come immediately, while the benefits would be diffuse and almost unnoticeable.

Far-UV-C may therefore prove to be not only a test of a technology, but also a test of modern societies’ capacity for long-term thinking.

This is an English translation of an article first published in Polish.

Footnotes

  1. Cambeiro J, Potter B. Indoor Air Quality Is the Next Great Public Health Challenge. Biotechnology. June 29th 2023 https://ifp.org/indoor-air-quality/ ↩ ↩2

  2. Buonanno M, Ponnaiya B, Welch D, Stanislauskas M, Randers-Pehrson G, Smilenov L, Lowy D.F, Owens M.D, Brenner J.D. Germicidal Efficacy and Mammalian Skin Safety of 222-nm UV Light. Radiat Res. 2017 Feb 22;187(4):483–491. https://pubmed.ncbi.nlm.nih.gov/28225654/ ↩ ↩2 ↩3

  3. Melikov K.A. COVID-19: Reduction of airborne transmission needs paradigm shift in ventilation. Build Environ. 2020 Oct 6;186:107336. https://pmc.ncbi.nlm.nih.gov/articles/PMC7536125/ ↩

  4. Reed G.N. The History of Ultraviolet Germicidal Irradiation for Air Disinfection. Public Health Rep. 2010 Jan-Feb;125(1):15–27. https://pmc.ncbi.nlm.nih.gov/articles/PMC2789813/ ↩

  5. Kaidzu S, Sugihara K, Sasaki M, Nishiaki A, Igarashi T, Tanito M. Evaluation of acute corneal damage induced by 222-nm and 254-nm ultraviolet light in Sprague-Dawley rats. Free Radic Res. 2019 Jun;53(6):611-617 https://pubmed.ncbi.nlm.nih.gov/30947566/ ↩

  6. Narita K, Asano K, Yamane K, Ohashi H, Igarashi T, Nakane A. Effect of ultraviolet C emitted from KrCl excimer lamp with or without bandpass filter to mouse epidermis. PLoS One. 2022 May 3;17(5):e0267957. doi: 10.1371/journal.pone.0267957. eCollection 2022. https://pubmed.ncbi.nlm.nih.gov/35503791/ ↩

  7. Eadie E, Hiwar W, Fletcher L, Tidswell E, O’Mahoney P, Buonanno M, Welch D, Adamson S.C, Brenner J.D, Noakes C, Wood K. Far-UVC (222 nm) efficiently inactivates an airborne pathogen in a room-sized chamber. Scientific Reports volume 12, Article number: 4373 (2022) https://pubmed.ncbi.nlm.nih.gov/35322064/ ↩

  8. Williamson D.R. Blueprint for Far-UVC. Blueprint Biosecurity. Version 1 (2025). https://blueprintbiosecurity.org/u/2025/06/Blueprint-for-Far-UVC-V1.0-6.5.25.pdf ↩

  9. Crider S.Y, Tsuchiya M, Mukundwa M, Ray I, Pickering J.A. Adoption of Point-of-Use Chlorination for Household Drinking Water Treatment: A Systematic Review. Environ Health Perspect. 2023 Jan 30;131(1):016001. doi: 10.1289/EHP10839 https://pmc.ncbi.nlm.nih.gov/articles/PMC9885856/ ↩