to commission research into the efficacy for reducing disease transmission, eye safety, and impacts on air quality of far-UVC light
Reducing the spread of infectious disease
Certain wavelengths of germicidal light called ‘far-UVC’ inactivate pathogens in the air and on surfaces while appearing to be safe for humans. Could this be a powerful tool for reducing the spread of infectious disease, and even stop or slow the next outbreak which could become a pandemic? This funding will be used to commission research into the safety profile of far-UVC, making it possible to understand how best to deploy it.
Blueprint Biosecurity is making calls for proposals that most efficiently and comprehensively address the outstanding questions. This funding is likely to be used to answer questions in the areas of eye safety and air quality.
Testing eye safety
When light shines on people, most of it is absorbed or reflected by their clothes. However, it is important that this kind of light is safe for people’s skin and eyes.
- There is already very good evidence that most far-UVC light is absorbed by the outer layers of the skin. These cells have no nucleus (where the DNA is), so, unlike other wavelengths of UV light, there is no risk of DNA damage and consequent cancer risk. For example, see Görlitz M, Justen L, Rochette PJ, et al. 2023, page 6.
- However, the most up-to-date standards for occupational use in the USA have a limit for eyes that is around 3 times lower than for skin, and there is relatively much less evidence for eye limits and safety in general. There is anecdotal evidence that far-UVC above certain levels can cause discomfort in the eye, even if there are no signs of long-lasting harm.
This funding will be used to study the question with the most important remaining uncertainties. That is photokeratitis, a temporary but painful condition of the outermost layer of the eye (the cornea). Improper installation of other UV technologies (not far-UVC) has caused photokeratitis in the past. Blueprint Biosecurity has now published its first request for proposals, seeking experiments to:
- “Determine the levels, if any, at which irritation/discomfort is experienced under far-UVC exposure, and how quickly any such symptoms disappear after exposure”;
- “Establish mechanism and cause of possible human eye irritation/discomfort under far-UVC exposure”; and
- “Develop satisfactory and sufficient models to predict possible far-UVC-induced effects that contribute to irritation/discomfort mechanisms in human eyes”.
Having a clear picture of the risk will help with:
- Knowing which ways of using far-UVC make sense. (This would, in turn, inform which far-UVC grants make sense, and how much to fund far-UVC work in general.)
- Knowing what regulatory limits make sense. (To get rid of as many germs as possible, the limits should be set as high as is safe, but no higher.)
Testing impacts on air quality
Beyond what happens when far-UVC light shines directly on people, Blueprint Biosecurity is investigating the reactions far-UVC causes (in small quantities) in the air, and whether they cause a problematic buildup of anything harmful.
- Far-UVC causes the production of a small amount of ozone (O3) and hydroxyl radicals (OH) from the oxygen and water in the air.
- These molecules react with volatile organic compounds in the air (e.g. limonene, which gives the lemon smell to many cleaning and other fragrant products) to form secondary organic aerosols. These are a type of fine particulate matter, which is a risk factor for health issues, mostly lung-related.
- far-UVC photons also interact directly with some volatile organic compounds, but this is not well studied.
The most valuable experiments to commission for this purpose could involve:
- Measuring how much ozone and fine particulate matter is produced in situations representative of real-life far-UVC deployments;
- Measuring the formation of secondary organic aerosols for the most concerning/prevalent volatile organic compounds in controlled experiments;
- Replicating past studies with surprising results to better understand them — such as one experiment where far-UVC caused much more pathogen inactivation and ozone production than expected;
- Better quantifying the potential health impacts of increased indoor ozone (all estimates currently trace back to one 2016 paper on outdoor ozone);
- Identifying mitigation strategies (e.g. removal as part of the ventilation system, ozone scrubbers, or benign materials that are known to be effective ozone sinks, such as clay); or
- Identifying new sensor technologies, as it is currently prohibitively expensive to monitor ozone with the level of accuracy that may be necessary.
If you might apply when Blueprint Biosecurity publishes a call for proposals on air quality, please do not take the above list as definitive. Blueprint Biosecurity is in the process of refining it.
As with eye safety, studying these issues will help understand what uses of far-UVC make sense.
A key motivation for this grant in particular is that Blueprint Biosecurity may be the best-placed group in the world to ensure that a wide range of experiments address the most important questions about far-UVC.
- In our experience, Blueprint Biosecurity is very focused on ensuring that its work is action-relevant.
- Blueprint Biosecurity has been working to identify the research outputs which would result in the most compelling and useful evidence on the photokeratitis question. We have read some of their internal notes and found them to be the most informative resources we have found on some of these issues.
- Blueprint Biosecurity will work with external researchers to help ensure that their experiments will answer our key questions.
Our key remaining uncertainty is simply how promising far-UVC will ultimately be in slowing down the worst future pandemics.
- It might be the case that far-UVC is impractical to deploy in sufficient intensity to have sufficient effect on transmission, or that this takeup does not happen for reasons unrelated to the safety and societal value.
- In particular, far-UVC is currently too expensive to deploy in a significant fraction of indoor spaces. This means that hardware R&D to produce far-UVC affordably is important. For the most part, this will likely be best done by companies.
- Experiments like those funded by this grant will help clarify other uncertainties like what intensities of light are very safe.