Latest News: Covid 19 and Air Neutralising
- Upper-room ultraviolet air disinfection might help to reduce COVID-19 transmission in buildings: a feasibility study.
Upper-room ultraviolet air disinfection might help to reduce COVID-19 transmission in buildings: a feasibility study.
Peerj, 13 Oct 2020, 8:e10196
DOI: 10.7717/peerj.10196 PMID: 33083158 PMCID: PMC7566754
Abstract: As the world’s economies come out of the lockdown imposed by the COVID-19 pandemic, there is an urgent need for technologies to mitigate COVID-19 transmission in confined spaces such as buildings. This feasibility study looks at one such technology, upper-room ultraviolet (UV) air disinfection, that can be safely used while humans are present in the room space, and which has already proven its efficacy as an intervention to inhibit the transmission of airborne diseases such as measles and tuberculosis. Using published data from various sources, it is shown that the SARS-CoV-2 virus, the causative agent of COVID-19, is highly likely to be susceptible to UV-C damage when suspended in air, with a UV susceptibility constant likely to be in the region 0.377-0.590 m2/J, similar to that for other aerosolised coronaviruses. As such, the UV-C flux required to disinfect the virus is expected to be acceptable and safe for upper-room applications. Through analysis of expected and worst-case scenarios, the efficacy of the upper-room UV-C approach for reducing COVID-19 transmission in confined spaces (with moderate but sufficient ceiling height) is demonstrated. Furthermore, it is shown that with SARS-CoV-2, it should be possible to achieve high equivalent air change rates using upper-room UV air disinfection, suggesting that the technology might be particularly applicable to poorly ventilated spaces.
Conclusions: In conclusion, we have been able to demonstrate that the SARS-CoV-2 virus is relatively easily inactivated by UV-C light and that when aerosolised the virus is likely to have a UV susceptibility constant, Zur, that is similar to that exhibited by other coronaviruses in air. This suggests that SARS-CoV-2 when suspended in air should be reasonably easy to inactivate using UV light at 254 nm. As such, upper-room UVGI may have potential as an intervention to inhibit the transmission of COVID-19 in buildings, especially in situations where achieving high ventilation rates might otherwise be impractical.
Full article can be read and downloaded from www.europepmc.org
- UV-C irradiation is highly effective in inactivating SARS-CoV-2 replication
UV-C irradiation is highly effective in inactivating SARS-CoV-2 replication
Abstract: The potential virucidal effects of UV-C irradiation on SARS-CoV-2 were experimentally evaluated for different illumination doses and virus concentrations (1000, 5, 0.05 MOI). At a virus density comparable to that observed in SARS-CoV-2 infection, an UV-C dose of just 3.7 mJ/cm 2 was sufficient to achieve a more than 3-log inactivation without any sign of viral replication. Moreover, a complete inactivation at all viral concentrations was observed with 16.9 mJ/cm 2 . These results could explain the epidemiological trends of COVID-19 and are important for the development of novel sterilizing methods to contain SARS-CoV-2 infection.
Preprint from medRxiv, 07 Jun 2020
DOI: 10.1101/2020.06.05.20123463 PPR: PPR172635
Full article can be read and downloaded from www.europepmc.org
- Rapid and complete inactivation of SARS-CoV-2 by ultraviolet-C irradiation
Rapid and complete inactivation of SARS-CoV-2 by ultraviolet-C irradiation
Authored by Storm, N., McKay, L.G.A., Downs, S.N. et al. Rapid and complete inactivation of SARS-CoV-2 by ultraviolet-C irradiation.
Sci Rep 10, 22421 (2020). https://doi.org/10.1038/s41598-020-79600-8
Abstract: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has devastated global public health systems and economies, with over 52 million people infected, millions of jobs and businesses lost, and more than 1 million deaths recorded to date. Contact with surfaces contaminated with droplets generated by infected persons through exhaling, talking, coughing and sneezing is a major driver of SARS-CoV-2 transmission, with the virus being able to survive on surfaces for extended periods of time. To interrupt these chains of transmission, there is an urgent need for devices that can be deployed to inactivate the virus on both recently and existing contaminated surfaces. Here, we describe the inactivation of SARS-CoV-2 in both wet and dry format using radiation generated by a commercially available Signify ultraviolet (UV)-C light source at 254 nm. We show that for contaminated surfaces, only seconds of exposure is required for complete inactivation, allowing for easy implementation in decontamination workflows.
Complete article can be read and downloaded from www.nature.com
- Irradiation with UV light kills SARS-CoV-2
Irradiation with UV light kills SARS-CoV-2
Researchers in Italy have found that it is possible to completely inactivate severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) using short-wavelength UV (UV-C) irradiation.
Journal reference: Clerici M, et al. UV-C irradiation is highly effective in inactivating and inhibiting SARS-CoV-2 replication. medRxiv 2020. doi: https://doi.org/10.1101/2020.06.05.20123463
- Susceptibility of SARS-CoV-2 to UV irradiation
Susceptibility of SARS-CoV-2 to UV irradiation
Christiane Silke Heilingloh, Ulrich Wilhelm Aufderhorst, Leonie Schipper, Ulf Dittmer, Oliver Witzke, Dongliang Yang, Xin Zheng, Kathrin Sutter, Mirko Trilling, Mira Alt, Eike Steinmann, Adalbert Krawczyk,
Susceptibility of SARS-CoV-2 to UV irradiation,
American Journal of Infection Control,
Volume 48, Issue 10,
Abstract: The coronavirus SARS-CoV-2 pandemic became a global health burden. We determined the susceptibility of SARS-CoV-2 to irradiation with ultraviolet light. The virus was highly susceptible to ultraviolet light. A viral stock with a high infectious titer of 5â€¯Ã—â€¯106Â TCID50/mL was completely inactivated by UVC irradiation after nine minutes of exposure. The UVC dose required for complete inactivation was 1,048 mJ/cm2. UVA exposure demonstrated only a weak effect on virus inactivation over 15 minutes. Hence, inactivation of SARS-CoV-2 by UVC irradiation constitutes a reliable method for disinfection purposes in health care facilities and for preparing SARS-CoV-2 material for research purpose.
Keywords: COVID-19; Ultraviolet light; Inactivation
- SARS-CoV-2 is highly susceptible to irradiation with ultraviolet light.
- High viral loads of 5 * 106 TCID50/ml SARS-CoV-2 can be inactivated in 9 minutes by UVC irradiation.
- UVC irradiation represents a suitable disinfection method for SARS-CoV-2.
- Ultraviolet irradiation doses for coronavirus inactivation – review and analysis of coronavirus photoinactivation studies
Ultraviolet irradiation doses for coronavirus inactivation – review and analysis of coronavirus photoinactivation studies
GMS Hyg Infect Control. 2020; 15: Doc08.
Published online 2020 May 14. doi: 10.3205/dgkh000343
Results: “The available data reveals large variations, which are apparently not caused by the coronaviruses but by the experimental conditions selected. If these are excluded as far as possible, it appears that coronaviruses are very UV sensitive. The upper limit determined for the log-reduction dose (90% reduction) is approximately 10.6 mJ/cm2 (median), while the true value is probably only 3.7 mJ/cm2 (median).”
Conclusion: “Since coronaviruses do not differ structurally to any great exent, the SARS-CoV-2 virus – as well as possible future mutations – will very likely be highly UV sensitive, so that common UV disinfection procedures will inactivate the new SARS-CoV-2 virus without any further modification.”
- Disinfectant Activity of A Portable Ultraviolet C Equipment
Disinfectant Activity of A Portable Ultraviolet C Equipment
Guridi, Andrea; Sevillano, Elena; de la Fuente, Iñigo; Mateo, Estibaliz; Eraso, Elena; Quindós, Guillermo. 2019. “Disinfectant Activity of A Portable Ultraviolet C Equipment” Int. J. Environ. Res. Public Health 16, no. 23: 4747. https://doi.org/10.3390/ijerph16234747
Conclusion: “Physical UVC disinfection is a reliable alternative to chemical disinfection due to the increase of chemical-resistant microorganisms and the emission of harmful by-products after chemical treatment. Moreover, UVC disinfection does not generate toxins or volatile organic compounds and does not require storage of hazardous materials.”
- Potential application of Air Cleaning devices
Potential application of Air Cleaning devices and personal decontamination to manage transmission of COVID-19
SAGE-EMG 4th November 2020
“Application of air cleaning devices may be a useful strategy to reduce airborne transmission risks in poorly ventilated spaces (medium confidence). Air cleaning devices have limited benefit in spaces that are already adequately ventilated, and are not necessary for adequately ventilated buildings unless there are identified specific risks (medium confidence).”
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- Airborne transmission of covid-19
Airborne transmission of covid-19
BMJ 2020; 370 doi: https://doi.org/10.1136/bmj.m3206 (Published 20 August 2020) Cite this as: BMJ 2020;370:m3206
“Currently, aerosol generating procedures for low risk patients are often delayed or denied, and when they do go ahead are conducted with meticulous and expensive airborne precautions, while higher risk patients who are coughing, talking, and breathless are cared for by staff wearing just a surgical mask. Retrospective studies from China have observed higher rates of SARS-CoV-2 infection among staff treating low risk patients and using droplet precautions than among those wearing respirators to treat higher risk patients.1112“
- Covid-19: Airborne transmission is being underestimated, warn experts
Covid-19: Airborne transmission is being underestimated, warn experts
BMJ 2020; 370 doi: https://doi.org/10.1136/bmj.m2720 (Published 07 July 2020) Cite this as: BMJ 2020;370:m2720
“Studies by the signatories and other scientists have demonstrated beyond any reasonable doubt that airborne droplets can pose a risk beyond 2 m from an infected person, the authors argued. They cited the case of a Chinese restaurant where video captured an evening in which the virus spread from one table to others with no evidence of contact, direct or indirect, between the diners.”