Technical ReportPDF Available

2020 COVID-19 Coronavirus Ultraviolet Susceptibility

  • Weill Cornell Medicine of Cornell University and New York Presbyterian Hospital
  • Weill Cornell Medicine of Cornell University


This report addresses a topic of high current interest - the ultraviolet susceptibility of SARS-CoV-2, the virus that causes COVID-19 disease. The results of a literature review are presented and summarized to provide a basis for estimating the ultraviolet susceptibility of SARS-CoV-2, and relevant supplemental information is provided on COVID-19 based on the latest published reports. A discussion on the feasibility of using the new technology of Focused Multivector Ultraviolet light as a disinfection strategy is included.
PurpleSun Inc
21-21 41st Ave, Suite 5B, Long Island City, NY 11101
212-500-0859 1
2020 COVID-19 Coronavirus Ultraviolet Susceptibility
Memo from the Authors
The current global Coronavirus pandemic is of urgent concern with its high transmission rate and rapid
spread throughout the world. The current reported death rate is 2-3% and there currently is no antiviral
drugs or vaccine available to the public. Structurally, this virus is not unique and is similar to other
coronaviruses such as Severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome
(MERS), and can be addressed with existing disinfection methods such as chemicals and new
technologies such as Focused Multivector Ultraviolet (FMUV) from PurpleSun.
Answers to Frequently Asked Questions
1. How long does COVID-19 Live on Surfaces?
6 hours - 9 days on surfaces
2. What is the difference between a virus and bacteria?
Bacteria are self-contained, have cell walls, and can survive and replicate on their own.
Viruses are DNA molecules that may be naked or encapsulated and require a host to replicate.
They cannot be treated with antibiotics and require a vaccine
3. What is the biggest issue with this COVID-19 virus?
High secondary infection rate, Rapid spread (more rapid than SARS or MERS), Fatality rate (2-
4. Is ultraviolet light effective against COVID-19?
Ultraviolet light destroys DNA of viruses, bacteria, and fung
5. What is the appropriate Personal Protective Equipment (PPE) for healthcare staff?
General Explanation of the Disease
COVID-19 is the respiratory disease caused by the SARS-CoV-2 virus that has caused outbreaks
worldwide. The SARS-CoV-2 is a new variant in the betacoronavirus family (Fisher 2020). It transmits by
direct contact or contact with fomites and can be suspended in air as well, as are the related
betacoronaviruses SARS, MERS, and the four known Human coronaviruses OC43, 229E, NL63, and
HKU1. The majority of infection transmissions are believed to be by droplet spray from coughing and
sneezing and by direct contact or contact with fomites.
Confirmation That Ultraviolet is Effective
Ultraviolet light can be an effective measure for decontaminating surfaces that may be contaminated by
the SARS-CoV-2 virus by inducing photodimers in the genomes of microorganisms. Ultraviolet light has
been demonstrated to be capable of destroying viruses, bacteria and fungi in hundreds of laboratory
studies (Kowalski 2009). The SARS-CoV-2 virus has not yet been specifically tested for its ultraviolet
susceptibility but many other tests on related coronaviruses, including the SARS coronavirus, have
concluded that they are highly susceptible to ultraviolet inactivation. This report reviews these studies and
provides an estimate of the ultraviolet susceptibility.
It is estimated that the SARS-CoV-2 virus can survive on surfaces for up to 9 days, based on its similarity
to SARS and MERS. Standard disinfectants are effective against SARS-CoV-2 but as an extra level of
PurpleSun Inc
21-21 41st Ave, Suite 5B, Long Island City, NY 11101
212-500-0859 2
protection, and to shield against errors in the manual disinfection process, ultraviolet light can be used to
disinfect surfaces and equipment after the manual chemical disinfection process is completed. ASHRAE
recommends ultraviolet germicidal irradiation as one strategy to address COVID-19 disease transmission
(ASHRAE 2020).
COVID-19 is highly contagious and so any residual contamination, no matter how small, can pose a threat
to healthcare workers and patients. The PurpleSun E300 Focused Multivector Ultraviolet (FMUV) system
with Shadowless DeliveryTM (see Figure 1) is an automated system that has proven to reduce surface
contamination by 96% and can address contamination left behind by current manual chemical cleaning
which was shown to only reduce contamination by 36% (Armellino 2020).
The PurpleSun E300 system has demonstrated elimination of 99%-99.99% of bacteria and fungi as listed
in Table 2 in laboratory tests within 90 seconds (Petraitis 2017). Similar reductions could be expected
against the COVID-19 coronavirus in 90 seconds as well.
Scientific Rationale
Coronaviruses are members of the Coronaviridae group and contain a single-stranded, positive-sense
RNA genome surrounded by a corona-like helical envelope (Ryan 1994). Approximately 100 sequences
of the SARS-CoV-2 genome have been published and these suggest there are two types, Type I and
Type II, of which the latter came from the Huanan market in China while the Type I strain came from an
unknown location (Zhang 2020). The genome consists of 29,751 base pairs (NC_045512.2) and the
genome is about 80% homologous with SARS viruses (NCBI 2020, Fisher 2020). Coronaviruses have a
size range of 60-140nm, with a mean size of 0.10 microns (Zhu 2020).
Table 1 summarizes the results of studies that have been performed on Coronaviruses under ultraviolet
light exposure, with the specific species indicated in each case. The D90 value indicates the ultraviolet
dose for 90% inactivation. Although there is a wide range of variation in the D90 values, this is typical of
laboratory studies on ultraviolet susceptibility. The range of D90 values for coronaviruses is 7-2410 J/m2
and the average of all studies is 237 J/m2. However, the study by Walker (2007) is an airborne study and
is an outlier in this set of water-based studies. Also, the studies by Weiss (1986) and Darnell (2004) are
outliers on the low and high ends. Excluding outliers, the mean D90 is 47 J/m2, and this should
adequately represent the ultraviolet susceptibility of the SARS-CoV-2 (COVID-19) virus.
Two recent studies on SARS-CoV-2 have been added to Table 1 (Inagaki 2020, Bianco 2020). The
average value of the D90 is 27 J/m2, which suggests the average value for all coronaviruses reported
above (47 J/m2) is conservative. Both of these studies indicate tailing in the survival curve above about 3-
6 logs of reduction, beyond which the D90 value will not be an accurate predictor (Blatchley 2020).
PurpleSun Inc
21-21 41st Ave, Suite 5B, Long Island City, NY 11101
212-500-0859 3
D90 Dose
UV k m2/J Base Pairs kb Source
Coronavirus 6.6 0.35120 30741
Walker 2007a
Berne virus (Coronaviridae) 7.2 0.32100 28480 Weiss 1986
SARS-CoV-2 (Italy-INMI1) 12.3 0.18670 29811 Bianco 2020
Murine Coronavirus (MHV) 15.0 0.15351 31335 Hirano 1978
SARS Coronavirus (Frankfurt 1) 16.4 0.14040 29903 Eickmann 2020
Canine Coronavirus (CCV) 28.5 0.08079 29278
Saknimit 1988b
Murine Coronavirus (MHV) 28.5 0.08079 31335
Saknimit 1988b
SARS Coronavirus (CoV-P9) 40.0 0.05750 29829
Duan 2003c
SARS-CoV-2 (SARS-CoV-2/Hu/DP/Kng/19-027) 41.7 0.05524 29811 Inagaki 2020
Murine Coronavirus (MHV) 103.0 0.02240 31335 Liu 2003
SARS Coronavirus (Hanoi) 133.9 0.01720 29751
Kariwa 2004d
SARS Coronavirus (Urbani) 2410 0.00096 29751 Darnell 2004
Average 237 0.00972
Average excluding outliers 47 0.04943
Average for SARS-CoV-2 27 0.08528
a(Jingwen 2020) b(estimated) c(mean estimate) d(at 3 logs)
Table 1: Summary of Ultraviolet Studies on Coronaviruses
including all studies
excluding Walker, Weiss & Darnell
two studies, 90% inactivation
PurpleSun Inc
21-21 41st Ave, Suite 5B, Long Island City, NY 11101
212-500-0859 4
Figure 1: The PurpleSun E300 FMUV system in PACT configuration for transport or storage
(Left), CUBE configuration for surrounding smaller equipment (Center), and RECTAN mode for
surrounding larger equipment (Right).
Updated on July 7, 2020 by:
Dr. Wladyslaw J. Kowalski, PhD, Chief Scientist and World UV Expert, PurpleSun Inc
Dr. Thomas J. Walsh, MD, PhD, Infectious Diseases Translational Research Laboratory, Weill Cornell
Medicine of Cornell University, New York City, NY
Dr. Vidmantas Petraitis, MD, Infectious Diseases Translational Research Laboratory, Weill Cornell
Medicine of Cornell University, New York City, NY
1. Armellino D, Walsh TJ, Petraitis V, Kowalski W. (2019). Assessment of focused multivector ultraviolet
disinfection with shadowless delivery using 5-point multisided sampling of patient care equipment without
manual-chemical disinfection. Am J Infect Control 47,409-414.
2. Armellino D GK, Thomas L, Walsh T, Petraitis V. (2020). Comparative evaluation of operating room terminal
cleaning by two methods: Focused multivector ultraviolet (FMUV) versus manual-chemical disinfection Am J
Infect Contr (Accepted).
3. ASHRAE. (2020). ASHRAE Resources Available to Address COVID-19 Concerns. (American Society of
Heating, Refrigerating and Air-Conditioning Engineers, Atlanta, GA).
4. Bianco A, M Biasin, G Pareschi et al. (2020). UV-C irradiation is highly effective in inactivating and
inhibiting SARS-CoV-2 replication. medRxiv preprint doi: (unreviewed preprint).
5. Blatchley ER, Petri B, Sun W. (2020). SARS-CoV-2 UV Dose-Response Behavior. International Ultraviolet
Association (IUVA) White Paper.
PurpleSun Inc
21-21 41st Ave, Suite 5B, Long Island City, NY 11101
212-500-0859 5
6. Darnell MER, Subbarao K, Feinstone SM, Taylor DR. (2004). Inactivation of the coronavirus that induces
severe acute respiratory syndrome, SARS-CoV. J Virol Meth 121,85-91.
7. Duan SM, Zhao XS, Wen RF, Huang JJ, Pi GH, Zhang SX, Han J, Bi SL, Ruan L, Dong XP. (2003). Stability
of SARS Coronavirus in Human Specimens and Environment and its Sensitivity to Heating and Environment
and UV Irradiation. Biomed Environ Sci 16,246-255.
8. Eickmann M, Gravemann U, Handke W, Tolksdorf F, Reichenberg S, M€uller TH, Seltsam A. (2020).
Inactivation of three emerging viruses severe acute respiratory syndrome coronavirus, CrimeanCongo
haemorrhagic fever virus and Nipah virus in platelet concentrates by ultraviolet C light and in plasma by
methylene blue plus visible light. Vox Sanguinis 115:146-151.
9. Fisher D, Heymann D. (2020). Q&A: The novel coronavirus outbreak causing COVID-19. BMC Med 18,57.
10. Hirano N, Hino S, Fujiwara K. (1978). Physico-chemical properties of mouse hepatitis virus (MHV-2) grown on
DBT cell culture. Microbiol Immunol 22,377-90.
11. Inagaki H, A Saito, H Sugiyama, T Okabayashi, S Fujimoto. (2020). Rapid inactivation of SARS-
CoV-2 with Deep-UV LED irradiation. bioRxiv preprint doi: (unreviewed preprint).
12. Jingwen C, Li L, Hao W. (2020). Review of UVC-LED Deep Ultraviolet Killing New NCP Coronavirus Dose.
In Technology Sharing. (Hubei Shenzi Technology Co., Ltd.
13. Kariwa H, Fujii N, Takashima I. (2004). Inactivation of SARS coronavirus by means of povidone-iodine,
physical conditions, and chemical reagents. Jpn J Vet Res 52,105-112.
14. Kowalski W, Bahnfleth W, Raguse M, Moeller R. (2019). The Cluster Model of Ultraviolet Disinfection
Explains Tailing Kinetics. J Appl Microbiol 128,1003-1014.
15. Kowalski WJ. (2009). Ultraviolet Germicidal Irradiation Handbook: UVGI for Air and Surface Disinfection.
(Springer, New York).
16. Liu Y, Cai Y, Zhang X. (2003). Induction of caspase-dependent apoptosis in cultured rat oligodendrocytes by
murine coronavirus is mediated during cell entry and does not require virus replication. J Virol 77,11952-63.
17. NCBI. (2020). Genome Database (
18. Petraitis V PR, Schuetz AN, K. Kennedy-Norris K, Powers JH, Dalton SL, Petraityte E, Hussain KA, Kyaw ML,
Walsh TJ. . (2014). Eradication of medically important multidrug resistant bacteria and fungi using PurpleSun
Inc. multivector UV technology. . In IDWeek. (IDWeek, Philadelphia, PA.
19. Ryan KJ. (1994). Sherris Medical Microbiology. (Appleton & Lange, Norwalk).
20. Saknimit M, Inatsuki I, Sugiyama Y, Yagami K. (1988). Virucidal efficacy of physico-chemical treatments
against coronaviruses and parvoviruses of laboratory animals. Jikken Dobutsu 37,341-345.
21. Walker CM, Ko G. (2007). Effect of ultraviolet germicidal irradiation on viral aerosols. Environ Sci Technol
22. Weiss M, Horzinek MC. (1986). Resistance of Berne virus to physical and chemical treatment. Vet Microbiol
23. Zhang L, Yang Y-R, Zhang Z, Lin Z. (2020). Genomic variations of COVID-19 suggest multiple outbreak
sources of transmission. medRIX (preprint).
24. Zhu N, Zhang D, Wang W, Li X, Yang B, Song J, Zhao X, Huang B, Shi W, Lu R and others. (2020). A Novel
Coronavirus from Patients with Pneumonia in China, 2019. N Engl J Med 382,727-733.
... In their article, Kowalski et al. 2020 [55], based on hundreds of laboratory studies, Figure 14. Example of typical arrangement. ...
... In their article, Kowalski et al. 2020 [55], based on hundreds of laboratory studies, demonstrated that ultraviolet light is capable of inactivating viruses, bacteria, and fungi. The author has summarized the result of the exposure of coronaviruses to ultraviolet light and concluded that 90% (D90) virus inactivation is obtained for a radiation dose of 7-241 J/m 2 with an average of 67 J/m 2 . ...
... Summary of ultraviolet studies on coronaviruses (data processed from[55]). ...
Full-text available
This article presents a review of the main aspects regarding the current rules of classification societies, standards, and practice regarding the design and construction of ventilation and air conditioning systems for different compartments in different types of ships. In the context of the COVID-19 pandemic, this paper also presents the usual practice of the actual heating ventilation and air conditioning (HVAC) systems used on large ships, which recirculate the air between living compartments, in comparison with the new requirements to avoid the risk of spreading diseases. According to the rules, the technical compartments are provided with independent ventilation systems that ensure high air flow rates; therefore, the spread of diseases through this system is not an issue. The living spaces are provided with common ventilation and air conditioning systems that recirculate the air in all compartments served. The current practice of air recirculation in various living rooms leads to the spread of diseases, which should therefore be analyzed and improved by adding high-efficiency particulate air (HEPA) filters and UV disinfection or be replaced with individual systems that provide local heating or cooling without air recirculation between different rooms and fresh air supply with complete evacuation. For existing ships, different solutions should be analyzed such as reducing or cancelling recirculation and increasing filtration.
... Moreover, the procedure is very costly. Again, there has been a significant amount of research [15]- [21] recently about the required amount of UVC irradiation for the inactivation of SARS-CoV-2 (coronavirus). The research findings of these studies can be utilized by developing a mobile robotic platform to address the limitations of the static UVC disinfection method. ...
... However, the performance of the robot in the case of inactivating coronavirus can be estimated from the generated output of the conducted tests. Recent studies [15]- [21] stated that the rational lethal dose for inactivation of coronavirus is 3.75 mJsec/cm 2 . During the disinfection process of the evaluation study, the robot was controlled within a range of 40% to 55% of its maximum speed, which has ensured irradiation of 9.375 mJsec/cm 2 to 6.82 mJsec/cm 2 on the sample surfaces. ...
Full-text available
During the COVID-19 pandemic, surface disinfection using prevailing chemical disinfection methods had several limitations. Due to cost-inefficiency and the inability to disinfect shaded places, static UVC lamps cannot address these limitations properly. Moreover, the average market price of the prevailing UVC robots is huge, approximately 55,165 USD. In this research firstly, a requirement elicitation study was conducted using a semi-structured interview approach to reveal the requirements to develop a cost-effective UVC robot. Secondly, a semi-autonomous robot named UVC-PURGE was developed based on the revealed requirements. Thirdly, a two-phased evaluation study was undertaken to validate the effectiveness of UVC-PURGE to inactivate the SARS-CoV-2 virus and the capability of semi-autonomous navigation in the first phase and to evaluate the usability of the system through a hybrid approach of SUPR-Q forms and subjective evaluation of the user feedback in the second phase. Pre-treatment swab testing revealed the presence of both Gram-positive and Gram-Negative bacteria at 17 out of 20 test surfaces in the conducted tests. After the UVC irradiation of the robot, the microbial load was detected in only 2 (1D and 1H) out of 17 test surfaces with significant reductions (95.33% in 1D and 90.9% in 1H) of microbial load. Moreover, the usability evaluation yields an above-average SUPR-Q score of 81.91% with significant scores in all the criteria (usability, trust, loyalty, and appearance) and the number of positive themes from the subjective evaluation using thematic analysis is twice the number of negative themes. Additionally, compared with the prevailing UVC disinfection robots in the market, UVC-PURGE is cost-effective with a price of less than 800 USD. Moreover, small form factor along with the real time camera feedback in the developed system helps the user to navigate in congested places easily. The developed robot can be used in any indoor environment in this prevailing pandemic situation and it can also provide cost-effective disinfection in medical facilities against the long-term residual effect of COVID-19 in the post-pandemic era.
... The biggest problem for the UVB LEDs is the low EQE, that reach in this range values of about 10%, limited from several factors including all the internal, injection and extraction efficiencies. Instead, only in the last years, with a big push with the arrival of SARS-CoV2, there was an improvement in the realization technologies of UVC LEDs, where the queen application is the disinfection of surfaces [43][44][45]. In fact, as demonstrated [19,21,46] the range 240-280 nm is the best to induce modification of DNA and/or RNA in microorganisms, blocking their reproduction also with small optical power densities (> 10 mJ/cm 2 ). ...
... Instead, only in the last years, with a big push with the arrival of SARS-CoV2, there was an improvement in the realization technologies of UVC LEDs, where the queen appli-cation is the disinfection of surfaces [43][44][45]. In fact, as demonstrated [19,21,46] the range 240-280 nm is the best to induce modification of DNA and/or RNA in microorganisms, blocking their reproduction also with small optical power densities (>10 mJ/cm 2 ). ...
Full-text available
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the etiologic agent of COVID-19, which has affected the international healthcare systems since the beginning of 2020. Among sanitizing approaches, UV irradiation is a well-known technology often used in different environments to reduce the microbial contamination and the viral transmission. In particular, several works have demonstrated that UVC radiation is able to inactivate SARS-CoV-2 compromising its viral genome and virion integrity. With this work we review and analyze the current status of the pandemic and the state of the art of the UV technology. With traditional UVC discharge lamps having a serious environmental issue, due to their working principle based on mercury, a primary focus is shifted on the aluminum gallium nitride based deep-ultraviolet light emitting diodes. These devices are exploited for compact and environmentally friendly disinfection systems, but efficiency and reliability still play a limiting role into their mass market adoption and system efficacy. In this work we then analyze the latest reports on the effects of dose and wavelength on viral inactivation, thus providing two key pillars for the development of UVC based disinfection systems: the status of the technology and a quantitative evaluation of the dose required to achieve an effective coronavirus inactivation.
... Kampf et al. 17 also demonstrated that sodium hypochlorite solution at a concentration of 0.1% and 0.5% were effective with a reduction of viral infectivity > 3.0 log10 in 1 min. The ultraviolet rays are known to destroy the DNA of the virus 18 . The radiations from the far-UVC warp the structure of the genetic material of the virus and prevent the viruses from making more copies of themselves. ...
Full-text available
The development of new approaches for the decontamination of surfaces is important to deal with the processes related to exposure to contaminated surfaces. Therefore, was evaluated the efficacy of a disinfection technology using ozonized water (0.7–0.9 ppm of O3) on the surfaces of garments and accessories of volunteers, aiming to reduce the spread of microbial pathogens in the workplace and community. A Log10 microbial reduction of 1.72–2.40 was observed between the surfaces tested. The microbial reductions remained above 60% on most surfaces, and this indicated that the disinfection technology was effective in microbial log reduction regardless of the type of transport used by the volunteers and/or their respective work activities. In association with the evaluation of efficacy, the analysis of the perception of use (approval percentage of 92.45%) was fundamental to consider this technology as an alternative for use as a protective barrier, in conjunction with other preventive measures against microbiological infections, allowing us to contribute to the availability of proven effective devices against the spread of infectious agents in the environment.
... Ultraviolet is classified as UV-A, UV-B, and UV-C; the last, with wavelengths of 100 and 280 nm, is used for the disinfection of drinking water, wastewater, and sterilization of surfaces in contact with food, which favors DNA mutation. Kowalski et al. [77] proposed the use of 67 J/m 2 as the mean D90 dose, which is the UV dose for 90% inactivation. However, the most widely used disinfectants for vegetables in restaurants were bleach and potassium permanganate (55 and 31%, respectively), followed by salt/lemon or soap (7% each) in the home [78,79]. ...
Full-text available
On 11 March 2020, coronavirus disease 2019 (COVID-19) was declared a pandemic by the World Health Organization (WHO) and, up to 18:37 am on 9 December 2021, it has produced 268,440,530 cases and 5,299,511 deaths. This disease, in some patients, included pneumonia and shortness of breath, being transmitted through droplets and aerosols. To date, there is no scientific literature to justify transmission directly from foods. In this review, we applied the precautionary principle for the home and the food industry using the known "Five Keys to Safer Food" manual developed by the World Health Organization (WHO) and extended punctually in its core information from five keys, in the light of new COVID-19 evidence, to guarantee a possible food safety tool.
... Finally, for simulating the impact of in-duct UVGI treatment of air on the viruses, the built-in Penn State UVGI model in CONTAM [78,79] was used as an in-duct air disinfection system fitted to the return air side of the AHU. The UVGI susceptibility constant of 0.021 m 2 /J was used for a hypothetical mercury vapor system with 253.7 nm effective wavelength [80]. A combination of UVGI with MERV 13 filtration in the AHU, as well as MERV 13 filtration without the UVGI system, were also individually simulated. ...
Full-text available
The dispersion of indoor airborne contaminants across different zones within a mechanically ventilated building is a complex phenomenon driven by multiple factors. In this study, we modeled the indoor dispersion of airborne SARS-CoV-2 aerosols within a US Department of Energy detailed medium office prototype building using CONTAM software. The aim of this study is to improve our understanding about how different parts of a building can experience varying concentrations of the airborne viruses under different circumstances of release and mitigation strategies. Results indicate that unventilated stairwells can have significantly higher concentrations of airborne viruses. The mitigation strategies of morning and evening flushing of conditioned zones were not found to be very effective. Instead, a constant high percentage of outdoor air in the supply mix, and the use of masks, portable HEPA air cleaners, MERV 13 or higher HVAC air filters, and ultraviolet germicidal irradiation disinfection were effective strategies to prevent airborne viral contamination in the majority of the simulated office building.
... To inactivate the DNA or RNA of viruses, the UVC dose needs to be large enough. Furthermore, the impact of ultraviolet on different viruses has been investigated [38,39], showing that the average D90 value for several viruses is 47 J/m 2 . The UVC dose of 41.7 J/m 2 is enough to inactivate 90% of reproductive ability, especially for the SARS-CoV-2 (COVID-19) virus. ...
Full-text available
Due to the COVID-19 virus being highly transmittable, frequently cleaning and disinfecting facilities is common guidance in public places. However, the more often the environment is cleaned, the higher the risk of cleaning staff getting infected. Therefore, strong demand for sanitizing areas in automatic modes is undoubtedly expected. In this paper, an autonomous disinfection vehicle with an Ultraviolet-C (UVC) lamp is designed and implemented using an ultra-wideband (UWB) positioning sensor. The UVC dose for 90% inactivation of the reproductive ability of COVID-19 is 41.7 J/m2, which a 40 W UVC lamp can achieve within a 1.6 m distance for an exposure time of 30 s. With this UVC lamp, the disinfection vehicle can effectively sterilize in various scenarios. In addition, the high-accuracy UWB positioning system, with the time difference of arrival (TDOA) algorithm, is also studied for autonomous vehicle navigation in indoor environments. The number of UWB tags that use a synchronization protocol between UWB anchors can be unlimited. Moreover, this proposed Gradient Descent (GD), which uses Taylor method, is a high-efficient algorithm for finding the optimal position for real-time computation due to its low error and short calculating time. The generalized traversal path planning procedure, with the edge searching method, is presented to improve the efficiency of autonomous navigation. The average error of the practical navigation demonstrated in the meeting room is 0.10 m. The scalability of the designed system to different application scenarios is also discussed and experimentally demonstrated. Hence, the usefulness of the proposed UWB sensor applied to UVC disinfection vehicles to prevent COVID-19 infection is verified by employing it to sterilize indoor environments without human operation.
The ongoing emergency provoked by the SARS‐CoV‐2 pandemic demands the development of technologies to mitigate the spread of infection, and UV irradiation is a technique that can efficiently address this issue. However, proper use of UV equipment for disinfection requires an understanding of how the effects on SARS‐CoV‐2 are dependent on certain parameters. In this work, we determined the UV‐C inactivation constant k for SARS‐CoV‐2 using an LED source at λ=280 nm. Specifically, a Log3 reduction was measured after irradiation for 24 minutes with a delivered UV‐C dose of 23 J/m2. By multitarget model fitting, n=2 and k=0.32±0.02 m2/J were obtained. A lag time for the inactivation effect was also observed, which was attributed to the low irradiation levels used to perform the study. The combination of k and delay time allows for reliable estimation of disinfection times in small, closed environments.
The ongoing Pandemic of COVID-19 caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has severely stressed the worldwide healthcare system and has created dangerous shortages of personal protective equipment (PPE) including N95 filtering facepiece respirators (FFRs). Even though suppliers struggled to meet global demand for N95 masks at an unprecedented level, a shortage of FFR appears as a significant factor in the transmission of the disease to frontline workers. CDC, USA has mentioned that FFR decontamination and reuse may be necessary during times of shortage to ensure guaranteed availability. Hence present stressed condition faced by the healthcare sector seeks for an affordable decontamination strategy that can be replicated easily broadening the utility of FFR decontamination across a range of healthcare settings. After reviewing available literature on the various disinfection techniques that may be used for the decontamination of FFRs, a first of its kind, portable hybrid decontamination system/procedure has been conceptualized and designed. This system combines the disinfecting properties of both vaporous hydrogen peroxide (VHP) and ultra-violet C irradiation (UV C) to ensure maximum decontamination of N95 respirators. The instrument will be equipped with a hydrogen peroxide chamber and UV light source. Sterilization of the FFRs will be done through treatment with VHP followed by UV light treatment. The proposed system will allow the user to completely sterilize the FFRs in a time-efficient manner.
Full-text available
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). Both virus inactivation and replication inhibition were investigated as a function of these parameters. At a virus density comparable to that observed in SARS-CoV-2 infection, an UV-C dose of just 3.7 mJ/cm2 was sufficient to achieve a 3-log inactivation, and complete inhibition of all viral concentrations was observed with 16.9 mJ/cm2. 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.
Full-text available
In December 2019, a cluster of patients with pneumonia of unknown cause was linked to a seafood wholesale market in Wuhan, China. A previously unknown betacoronavirus was discovered through the use of unbiased sequencing in samples from patients with pneumonia. Human airway epithelial cells were used to isolate a novel coronavirus, named 2019-nCoV, which formed another clade within the subgenus sarbecovirus, Orthocoronavirinae subfamily. Different from both MERS-CoV and SARS-CoV, 2019-nCoV is the seventh member of the family of coronaviruses that infect humans. Enhanced surveillance and further investigation are ongoing. (Funded by the National Key Research and Development Program of China and the National Major Project for Control and Prevention of Infectious Disease in China.).
Full-text available
Disinfection by low-pressure monochromatic ultraviolet (UVC) radiation (253.7 nm) became an important technique to sanitize drinking water and also wastewater in tertiary treatments. In order to prevent the transmission of waterborne viral diseases, the analysis of the disinfection kinetics and the quantification of infectious viral pathogens and indicators are highly relevant and need to be addressed. The families Adenoviridae and Polyomaviridae comprise human and animal pathogenic viruses that have been also proposed as indicators of fecal contamination in water and as Microbial Source Tracking tools. While it has been previously suggested that dsDNA viruses may be highly resistant to UVC radiation compared to other viruses or bacteria, no information is available on the stability of polyomavirus toward UV irradiation. Here, the inactivation of dsDNA (HAdV2 and JCPyV) and ssRNA (MS2 bacteriophage) viruses was analyzed at increasing UVC fluences. A minor decay of 2-logs was achieved for both infectious JC polyomaviruses (JCPyV) and human adenoviruses 2 (HAdV2) exposed to a UVC fluence of 1,400 J/m2, while a decay of 4-log was observed for MS2 bacteriophages (ssRNA). The present study reveals the high UVC resistance of dsDNA viruses, and the UV fluences needed to efficiently inactivate JCPyV and HAdV2 are predicted. Furthermore, we show that in conjunction with appropriate mathematical models, qPCR data may be used to accurately estimate virus infectivity.
The spread of novel coronavirus disease 2019 (COVID-19) infections worldwide has raised concerns about the prevention and control of SARS-CoV-2. Devices that rapidly inactivate viruses can reduce the chance of infection through aerosols and contact transmission. This in vitro study demonstrated that irradiation with a deep ultraviolet light-emitting diode (DUV-LED) of 280 ± 5 nm wavelength rapidly inactivates SARS-CoV-2 obtained from a COVID-19 patient. Development of devices equipped with DUV-LED is expected to prevent virus invasion through the air and after touching contaminated objects.
Aims: To develop a new mathematical model derived from first principles to define the kinetics of ultraviolet disinfection and to explain the phenomenon known as tailing. The theory presented interprets tailing as the result of photoprotection due to cumulative Mie scattering effects in clustered populations of microorganisms. Methods and results: Mie scattering effects at ultraviolet wavelengths are used to compute a Shielding Constant for each microorganism based on the Average Projected Diameter. An Intrinsic Rate Constant, hypothesized to be a characteristic property of the microbial genome alone, is computed. The Cluster Model is fitted to tailing data from 30 ultraviolet inactivation studies and results are compared with the classic Two Stage Multihit Model. Conclusions: The Cluster Model demonstrates a statistically significant improvement in the mean adjusted R2 values of the tested data sets (p < 0·0001). Tailing in survival curves is the direct consequence of the Gaussian distribution of cluster sizes and the Intrinsic Rate Constant is a real and critical parameter that defines ultraviolet susceptibility. Significance and impact of the study: The ultraviolet dose-response behavior of microorganisms can now be explained in terms of parameters that have physical meaning and that provide deep insight into the disinfection process.
Background: The aim of this study was to evaluate the performance of a focused multivector ultraviolet (FMUV) system employing shadowless delivery with a 90-second disinfection cycle for patient care equipment inside and outside the operating room (OR) suite without manual-chemical disinfection. Methods: A 5-point multisided sampling protocol was utilized to measure the microbial burden on objects inside and outside the OR environment in a 3-phase nonrandomized observational study. Surface sampling was performed pre- and postdisinfection in between cases (IBCs) to assess the performance of manual-chemical disinfection. FMUV system performance was separately assessed pre- and postdisinfection before the first case and IBCs. Additionally, visibly clean high-touch objects were sampled outside the OR, and the microbial burden reductions after FMUV disinfection were quantified without manual-chemical disinfection. Results: Manual-chemical disinfection reduced the active microbial burden on sampled objects IBCs by 52.8%-90.9% (P <.05). FMUV reduced the active microbial burden by 92%-97.7% (P <.0001) before the first case and IBCs combined, and 96.3%-99.6% (P <.0001) on objects outside the OR without chemical disinfection. Conclusions: Five-point multisided sampling proved effective for assessing disinfection performance on all exterior sides of equipment. FMUV produced significant overall reductions of the microbial burden on patient care equipment in all study phases and independent of manual cleaning and chemical disinfection. (Please contact Dr. Kowalski directly for a PDF of this article)
This book is a comprehensive source for technical information regarding ultraviolet germicidal irradiation (UVGI) and its application to air and surface disinfection for the control of pathogens and allergens. The primary focus is on airborne microbes and surface contamination applications for hospitals, commercial facilities, and residential homes. All aspects of UVGI systems, including design methods, sizing methods, modeling, safety, installation, testing, guidelines, and disinfection theory are addressed in detail. An extensive database of over six hundred UV rate constant studies is included as well as tabular performance data for UV lamps and products. Providing this information in one single source simplifies the design and installation of UVGI systems, helps guarantee effective performance of new systems, and facilitates their use on a wide scale for the purpose of improving human health. This book is organized to provide systematic coverage of all related issues and will serve equally well as both a textbook and a handbook for general reference.
Some properties of a strain of mouse hepatitis virus, MHV-2, grown on DBT cells were determined using a plaque assay on the cells. Viral growth was not inhibited by the presence of actinomycin D or 5-iodo-2-deoxyuridine. MHV-2 was completely inactivated by ether, chloroform, sodium deoxycholate or beta-propiolactone, but showed a moderate resistance to trypsin. Heating at 56 C for 30 min did not completely abolish the virus infectivity. The virus was stable after heating at 50 C for 15 min in 1M-MgCl2 or 1M-MgSO4 as well as at 37 C for 60 min at pH 3.0 to 9.0. Infectivity was decreased to 1/100 and 1/400 after storing at 4 C for 30 days and 37 C for 24 hr, respectively. The virus passed through a 200-nm but not a 50-nm Sartorius membrane filter. The buoyant density of MHV-2 was 1.183 g/cm3 in sucrose gradient, and the fraction contained coronavirus-like particles measuring 70 to 130 nm in diameter. Survival rate was 10% after exposure to ultraviolet at 150 ergs/mm2. Freezing and thawing or sonication at 20 kc for 3 min did not affect the virus titer. No hemagglutinin was demonstrable with red blood cells of the chicken, Japanese quail, mouse, rat, hamster, guinea pig, sheep, bovine or human.
Virucidal efficacy of chemical disinfectants, heating and ultraviolet radiation against mouse hepatitis virus (MHV), canine coronavirus (CCV), Kilham rat virus (KRV) and canine parvovirus (CPV) were examined. Coronaviruses (MHV and CCV) were inactivated by ethanol, isopropanol, benzalkonium chloride, iodophor, sodium hypochlorite, sodium chlorite, cresol soap and formaldehyde as well as by heating at 60 degrees C for 15 minutes, whereas parvoviruses (KRV and CPV) appeared to be inactivated by disinfectants such as formaldehyde, iodophor, sodium hypochlorite and sodium chlorite. Parvoviruses were stable under heating of up to 80 degrees C for 30 minutes. Ultraviolet radiation inactivated all viruses within 15 minutes. No significant differences in stability against physico-chemical treatments were seen between viruses in the same group.