Data, Facts and Interpretations
Policy makers are required to interpret facts. It is vital that they are presented with all relevant information.
In public health policy, details matter. Recently two papers published in the John Hopkins University Journal Health Security, concluded that Far-UVC cannot currently be recommended for widespread adoption, in large part due to a need for more data concerning the risks of Far-UVC and ozone. Both papers focused solely on laboratory studies and models, omitting to cite important real world data demonstrating that Far-UVC operating at the correct dose and under basic ventilation levels does not result in any significant increase in ozone and associated secondary chemistry considered hazardous to human health.
The two papers recommended that Far-UVC is restricted to ‘high risk’ areas or emergency situations, suggesting it could be deployed in epidemic or pandemic scenarios. I view this as somewhat irrational. We are still facing repeated Covid-19 epidemics, and the threat of new emerging pandemics, which SARs-CoV-2 demonstrated could spread round the globe within days. The notion of responding to these with the wholesale installation of Far-UVC, a process that would take months or years, is not a credible strategy. There is no justifiable reason why we are not deploying Far-UVC now.
I believe that if you are presenting a scientific review, it is of fundamental importance to be accurate and comprehensive. This is particularly significant if the intention is to shape and inform public policy. In this case, the partial data coverage led to what I believe are distorted conclusions.
Make no mistake; if this advice is followed, people will suffer and die needlessly as a consequence. I have therefore submitted a formal complaint, with some suggested amendments. This has been acknowledged by the publishers and is now going through the formal complaints process. I will provide an update once the response is provided, but in the meantime I have copied the complaint below.
AS FOLLOWS:
Dear Editor,
I am writing to you to express my concern and to raise formal complaints about two recently published papers in the Health Security Journal. In both cases my complaint relates specifically to the sections on the impact of Far-UVC on indoor air quality. Both papers fail to discuss or include relevant references of published empirical data obtained from realistic real-world scenarios under the operation of Far-UVC devices. These are serious omissions, which in my opinion, create a distorted perspective and lead to misleading conclusions and recommendations that may have significant negative impacts on public health policy. Such shortcomings should, in my view, have been addressed at the peer review stage, if not by the original authors, and they are so serious that corrections or retractions should be urgently considered.
The papers of concern are;
Paper 1. Far UVC Technology and Germicidal Ultraviolet Energy: Policy and ResearchReview for Indoor Air Quality and Disease Transmission Control Linder AG, Zhu AW, Bruns R, Olsiewski P, Gronvall GK. Health Security. 2026;0(0). doi:10.1177/23265094261421824
Paper 2. Breaking Down Silos: A Multidisciplinary Approach to Mitigate Indoor Airborne Pathogen Transmission Zhu A, Bahnfleth WP, Bruns R, et al. Health Security. 2026;0(0). doi:10.1177/23265094261418814
Paper 1. Far UVC Technology and Germicidal Ultraviolet Energy: Policy and Research Review for Indoor Air Quality and Disease Transmission Control, finds that Far-UVC is highly efficient and effective at eliminating bacteria and viruses from indoor air, while being safe for skin and eye exposure.
However, in the section ‘Environmental Impacts of Far UVC and Interactions With Indoor Chemistry’ the authors discuss the issue of ozone, secondary organic aerosol (SOA) and Far-UVC at some length, citing in support of these concerns a number of studies deploying teflon chambers/oxidation flow reactors (OFRs) and computer simulations. (References 35, 37, 43, 45, 48). Furthermore, for unexplained reasons, a study of a high powered 254 nm sterilising device designed only for unoccupied spaces (ref.36) was also cited, despite not being relevant to the issue of 222 nm Far-UVC and indoor air quality. This should not have been included in this section and is misleading.
Only one real world Far-UVC 222nm study was cited (ref. 42 ‘Influence of germicidal UV (222 nm) lamps on ozone, ultrafine particles, and volatile organic compounds in indoor office spaces’). However, this study focused solely on how Far-UVC affects ozone/SOA levels in a series of office buildings when the HVAC systems were shut down, leaving the buildings running at unfeasibly low (and illegal) ventilation rates of 0.2 ach.
Even with virtually no ventilation, they found only modest increases in ozone with Far-UVC, at values still well below the equivalent rates found in teflon chamber experiments, and the results were inconclusive regarding the formation of secondary pollutants. Indeed, the referenced study authors state: “These discrepancies [lower ozone levels than teflon chamber studies] are attributed to the small volume of the test chambers, the higher O3 production rates caused by the increased reflectivity of the chamber materials compared to building materials, and the lower O3 decay rates caused by both limited surface deposition and gas-phase reactions”. In other words, they are saying that teflon chamber experiments are not representative of real-world scenarios when examining the potential impacts of Far-UVC on indoor air chemistry.
The authors of paper 1 then proceed to recommend that widespread adoption of Far-UVC should be delayed due to the concerns over indoor air chemistry. These conclusions are not supported by current real world empirical data which have consistently shown that Far- UVC devices operating at the minimum intensities required for disinfection, combined with basic ventilation rates, do not result in any significant increase in ozone and associated secondary chemistry considered hazardous to human health. [A number of these references that needed to be included are provided at the end of this letter].
At no point do the authors discuss the potential shortcomings of chamber/OFR/simulation studies. While such studies can provide useful insights, they are heavily dependent on methodology, the assumptions made and the quality of the input data, and we should always default to real world empirical observations whenever available. Critically, such real world observational data that is available was not cited or referenced in the commentary, and this is a significant oversight.
Paper 2. Breaking Down Silos: A Multidisciplinary Approach to Mitigate Indoor Airborne Pathogen Transmission, provides a broader overview on the different strategies available to mitigate pathogen transmission, but unfortunately falls into the same trap as Paper 1 when discussing the issue of Far-UVC and indoor air chemistry. Paper 2 references three of the same Far-UVC chamber/OFR/simulation models cited in Paper 1 (refs 85, 87 and 88) while also mistakenly including the same study of a high powered 254nm UVC disinfection device as referenced in Paper 1 (ref. 86 in this Paper), which is once again irrelevant to a discussion of Far-UVC. Yet again, there was no discussion of the limitations of chamber/OFR/simulation models studies, or of the tendency for these to overstate ozone production from Far-UVC, and no real world studies were included to portray more likely and realistic effects. Furthermore Paper 2 references Paper 1 (ref. 89) when stating that further study is required before Far-UVC can be safely deployed, despite ignoring existing research that contradicts this assertion.
In summary, the authors of both Paper 1 and Paper 2 failed to reference any of the several published papers based on realistic real-world scenario measurements of indoor ozone/SOA in the presence of Far-UVC devices. I believe that these glaring omissions materially alter the understanding and interpretation of the benefits and risks of Far-UVC as a critical public health tool, and could be construed as misinformation, although I am sure the authors did not intend this. However, in my view, these errors are serious, and if they serve to potentially slow down the wide-spread adoption of such an effective, life-saving technology, lives will be lost needlessly. The researchers, reviewers and publishers all have a responsibility to correct such errors. I would therefore politely request that corrections are made to both papers, to include;
i) Suitable references to real world scenario studies on indoor air quality relating to the operation of Far-UVC devices, to be included along with the results from computer simulations based on chamber/OFR experiments as already cited (see below for suggested references for additional inclusion).
ii) Substantive changes to the commentaries to discuss the shortcomings of teflon chamber/OFR/computer simulations studies in the context of Far-UVC and indoor air chemistry.
iii) Amendments to the conclusions to reflect current science and empirical real world data on the issue of Far-UVC and ozone/SOA, to state that there are no justifiable reasons to restrict the use of Far-UVC at the correct disinfection rates and under adequate ventilation rates to emergency situations only.
Whether we like it or not we remain in a health crisis. Recent data from the ONS and Eurostat confirm that healthy life expectancy across Europe and the UK has fallen sharply after 2020, and in many countries is still falling, demonstrating that something remains seriously wrong with public health management. Along with repeated epidemic waves of new Covid-19 variants, we also face the growing issue of multi-drug resistant microbes and the looming threat of further dramatic zoonotic spillover events such as H5N1. SARS-CoV-2 demonstrated that when faced with a newly emerging, highly transmissible pathogen we might have as little as 48hrs to prevent rapid global spread. Deploying Far-UVC across the public estate will take months, more likely years. The notion that we should only deploy Far-UVC widely if some new health emergency arises is irrational and not a credible strategy. It is vital that esteemed journals such as Health Security ensure that published work and policy guidance is comprehensive, up to date and understands the big picture context.
I would be grateful if you could consider this complaint and take the appropriate action.
Yours faithfully,
Dr N. J. Boyd
Additional references for inclusion
1. Narouei FH, Tang Z, Wang SI, Hashmi RH, Welch D, Sethuraman S, et al. (2025) Effects of germicidal far-UVC on ozone and particulate matter in a conference room. PLoS One 20(8): e0328224. https://doi.org/10.1371/journal.pone.0328224
2. Memic S, Kaple CE, Cadnum JL, Donskey CJ. Do far ultraviolet-C light technologies increase ozone concentrations in healthcare facility patient rooms? Infection Control & Hospital Epidemiology. 2025;46(8):858-860. doi:10.1017/ice.2025.10207
3. Petri Kalliomäki, Hamed Sobhani, Phillip Stratton, Kristen K. Coleman, AdityaSrikakulapu, Ross Salawitch, Russell R. Dickerson, Shengwei Zhu, Jelena Srebric, Donald K. Milton Ozone and ultra-fine particle concentrations in a hotel quarantine facility during 222 nm far-UVC air disinfection doi: https://doi.org/10.1101/2023.09.29.23296366
4. Buonanno, M., Kleiman, N.J., Welch, D. et al. 222 nm far-UVC light markedly reduces the level of infectious airborne virus in an occupied room. Sci Rep 14, 6722 (2024). https://doi.org/10.1038/s41598-024-57441-z
5. Brenner, D. J., The public-health significance of far-UVC-induced indoor ozone and its associated secondary chemistry, Photochemistry and Photobiology, 100, (2023) https://doi.org/10.1111/php.13892
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