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Ultraviolet irradiation doses for coronavirus inactivation -review and analysis of coronavirus photoinactivation studies Ultraviolette Bestrahlungsdosen für die Inaktivierung von Coronaviren -Review und Analyse von Coronavirusinaktivierungsstudien

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Background: To slow the increasing global spread of the SARS-CoV-2 virus, appropriate disinfection techniques are required. Ultraviolet radiation (UV) has a well-known antiviral effect, but measurements on the radiation dose necessary to inactivate SARS-CoV-2 have not been published so far. Methods: Coronavirus inactivation experiments with ultraviolet light performed in the past were evaluated to determine the UV radiation dose required for a 90% virus reduction. This analysis is based on the fact that all coronaviruses have a similar structure and similar RNA strand length. 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).
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Ultraviolet irradiation doses for coronavirus inactivation
– review and analysis of coronavirus photoinactivation
studies
Ultraviolette Bestrahlungsdosen für die Inaktivierung von Coronaviren
– Review und Analyse von Coronavirusinaktivierungsstudien
Abstract
Background: To slow the increasing global spread of the SARS-CoV-2
virus, appropriate disinfection techniques are required. Ultraviolet radi- Martin Heßling1
Katharina Hönes1
ation (UV) has a well-known antiviral effect, but measurements on the Petra Vatter1
radiation dose necessary to inactivate SARS-CoV-2 have not been pub-
lished so far. Christian Lingenfelder2
Methods: Coronavirus inactivation experiments with ultraviolet light
performed in the past were evaluated to determine the UV radiation 1 Institute of Medical
Engineering and
dose required for a 90% virus reduction. This analysis is based on the
fact that all coronaviruses have a similar structure and similar RNA
strand length. Mechatronics, Ulm University
of Applied Sciences, Ulm,
Germany
Results: The available data reveals large variations, which are apparently
not caused by the coronaviruses but by the experimental conditions 2 Pharmpur GmbH,
Königsbrunn, Germany
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.
Keywords: coronavirus, SARS-CoV, SARS-CoV-2, MERS-CoV, ultraviolet,
UVC, irradiation, inactivation, disinfection, Covid-19
Zusammenfassung
Hintergrund: Um die weltweite Ausbreitung des SARS-CoV-2 Virus zu
verlangsamen, werden geeignete Desinfektionstechniken benötigt. Ul-
traviolette Strahlung (UV) hat bekanntlich eine antivirale Wirkung, aber
Messungen zu benötigten Bestrahlungsdosen für die Inaktivierung von
SARS-CoV-2 sind bisher nicht veröffentlicht worden.
Material und Methoden: Coronavirusinaktivierungsexperimente, die in
der Vergangenheit durchgeführt wurden, werden herangezogen, um
die UV-Bestrahlungsdosis für eine 90%ige Virusreduktion zu ermitteln.
Die durchgeführte Analyse nutzt dabei die Tatsache, dass alle Corona-
viren eine ähnliche Struktur und eine vergleichbare RNA-Länge aufwei-
sen.
Ergebnisse: Die verfügbaren Daten weisen große Variationen auf, die
durch unterschiedliche experimentelle Bedingungen zu erklären sind.
Wenn extremere Versuchsbedingungen ausgeschlossen werden, zeigt
sich, dass Coronaviren sehr UV-empfindlich sind. Der ermittelte obere
Grenzwert für die log-Reduktionsdosis (90% Reduktion) beträgt ungefähr
10.6 mJ/cm2(Median), während der wahre Wert vermutlich nur etwa
3.7 mJ/cm2(Median) beträgt.
1/8GMS Hygiene and Infection Control 2020, Vol. 15, ISSN 2196-5226
Review Article
OPEN ACCESS
Schlussfolgerung: Da sich Coronaviren in ihrer Struktur nicht stark un-
terscheiden, wird auch das neue SARS-CoV-2 Virus – und mögliche zu-
künftige Mutationen – sehr UV-empfindlich sein, vermutlich sogar so
UV-empfindlich, dass etablierte UV-Desinfektionsverfahren das neue
SARS-CoV-2 Virus ohne zusätzliche Modifikationen effizient inaktivieren
können.
Schlüsselwörter: Coronavirus, SARS-CoV, SARS-CoV-2, MERS-CoV,
ultraviolette Strahlung, UVC, Bestrahlung, Inaktivierung, Desinfektion,
Covid-19
Introduction
The newest coronavirus disease COVID-19 is a highly
transmittable and pathogenic viral infection caused by
the severe acute respiratory syndrome coronavirus 2
(SARS-CoV-2), which emerged in Wuhan, China and
spread around the world. So far, more than 3.8 million
infections have led to more than 265,000 fatalities
worldwide [1].
The responsible pathogen, SARS-CoV-2, is an enveloped
single-stranded RNA virus and member of the family
coronavidae of the order nidovirales. All viruses of this
family exhibit very similar features. They have a spheroid
shape with a diameter of about 100–150 nm, are covered
with spike proteins on the outside, and have an RNA
strand length of 27–32 kb on the inside [2]. Four of these
coronaviruses are known to be the causative agents of
common colds (HCoV-229E, HCoV-NL63, HCoV-OC43 and
HCoV-HKU1), which usually only result in milder infections,
but the coronaviruses MERS-CoV (MERS: Middle East
Respiratory Syndrome) SARS-CoV and SARS-CoV-2 have
claimed many lives [3].
To stop the spread of SARS-CoV-2, several measures such
as containment, social distancing and wearing face masks
have been taken. Among other steps, hygiene procedures
have been intensified. The employment of liquid disinfec-
tants is one procedure that has been successful against
the 6 older coronaviruses [4]. Thermal disinfection has
also been proven to be quite effective, even at tempera-
tures as low as 60°C to 80°C [4].
Radiation disinfection, especially ultraviolet (UV) radiation,
is another well-known inactivation approach for all known
microorganisms and viruses that offers some advantages
over liquid disinfectants and heat sterilization. It can be
performed automatically and employed to disinfect sur-
faces, liquids, air and rooms, and it is also very energy-
efficient.
The ultraviolet spectrum is divided in 4 sections: Radiation
with a wavelength between 100 and 200 nm is called
vacuum ultraviolet radiation (VUV). It is usually not applied
for disinfection purposes because it is strongly absorbed
by air. The better-known ultraviolet ranges are UVC,
UVB, and UVA with spectral ranges of 200–280 nm,
280–315 nm, and 315–380 nm, respectively. Among
these last three UV ranges, UVC is the one with the
strongest antimicrobial/antiviral properties [5], [6]. For
RNA viruses, the main inactivation mechanism is illus-
trated in Figure 1A. UV radiation is absorbed by the RNA,
which leads to the formation of pyrimidine dimers, e.g.,
uracil dimers [6], [7].
The most common UVC light sources for many decades
now have been mercury discharge lamps, especially low-
pressure mercury vapor lamps, with a strong emission
peak at 254 nm, which is near the RNA absorption max-
imum at about 260 nm, as depicted in Figure 1B.
Although it is known that this kind of UVC radiation has
an inactivating effect on all microorganisms and viruses,
all pathogens require different UVC irradiation doses for
successful inactivation. For instance, the rotavirus re-
quires about 25 mJ/cm2of 254 nm UVC radiation from
a mercury discharge lamp for a 3-log reduction, but for
adenovirus (Type 40), the value is approximately 6 times
higher (140 mJ/cm2) [5], [8].
To answer the important question regarding SARS-CoV-2
and other coronaviruses as to which irradiation doses
are needed for inactivation, the existing coronavirus
photoinactivation results of the last 60 years have been
reviewed and analyzed in this study.
Materials and methods
Google Scholar and Pubmed were searched for different
combinations of the following terms: coronavirus, inacti-
vation, photoinactivation, disinfection, ultraviolet, radi-
ation, and light. In addition, a number of individual viruses
that belong to the families of coronaviruses although the
term “coronavirus” does not occur in their name were
also searched for, such as porcine epidemic diarrhea
virus, transmissible gastroenteritis virus, feline infectious
peritonitis virus, mouse hepatitis virus, sialodacryoadenitis
virus, hemagglutinating encephalomyelitis virus, and in-
fectious bronchitis virus.
The retrieved sources were evaluated according to the
type of sample irradiated (aerosol, surface, or liquid), the
type of light source (including emission peak wavelength),
the inactivation effect achieved, and the applied irradi-
ation dose.
If information on disinfection results for different irradi-
ation doses could be found in a single article, those de-
scribing a virus reduction by approx. 3–4 log levels were
selected. Results that were only displayed as illustrations
without the corresponding values in the text or tables
were read from previously enlarged figures.
If the necessary information was incomplete, e.g., be-
cause of missing irradiation details, the irradiation was
2/8GMS Hygiene and Infection Control 2020, Vol. 15, ISSN 2196-5226
Heßling et al.: Ultraviolet irradiation doses for coronavirus inactivation ...
Figure 1: A) Scheme of UV-RNA-damaging mechanism by dimer formation. B) Relative absorption spectra of RNA, relative
emission spectrum of a low-pressure mercury vapor lamp and transmission of a typical (Eagle) cell culture medium.
estimated by available lamp information, provided that
lamp type and distance were given or by other available
means. Publications in which radiation was combined
with photosensitizers or other chemical or biochemical
agents were excluded.
Subsequently, these data were employed to calculate the
log-reduction dose, i.e., the irradiation dose required for
a 90% virus reduction.
Results and discussion
About 30 publications of scientific investigations regarding
photoinactivation of coronaviruses were identified. This
included studies on CoV, SARS-CoV or MERS-CoV. An
overview of the results is presented by sample condition
and wavelength in Table 1.
Almost all experiments were performed with mercury va-
por lamps, with a peak emission at 254 nm (UVC), which
is near the RNA absorption peak in Figure 1. Individual
investigations were performed with peak wavelengths at
222 nm (UVC), or 365 nm (UVA), or even with daylight.
In most studies, the authors did not intend to investigate
the log-reduction doses of coronaviruses, but rather virus
inactivation in various applications. In all experiments
and for all coronaviruses, a successful virus inactivation
was observed. However, because of the different objec-
tives of the studies, the experimental conditions to de-
termine the specific log-reduction doses were often diffi-
cult to identify. In many cases, information important for
the present study’s analysis was missing.
To evaluate photoinactivation results, the basic inputs
were the virus reduction and the applied irradiation dose.
Not all authors provided the applied irradiation dose, but
at least for some studies this value could be calculated
as the product of irradiation duration and irradiation in-
tensity, or it could be estimated. For some investigations,
it was impossible to quantify the disinfection success
exactly; in these cases, the values were estimated based
on the information given in Table 1. However, for some
studies, it was even impossible to roughly estimate the
log-reduction dose.
The calculated and estimated results, given as log-reduc-
tion doses, exhibit extreme variability, even within the
254 nm results, ranging from 0.6 mJ/cm2(bovine corona
virus [9]) to 11,754 mJ/cm2(SARS (CoV Urbani) [10]).
Even the differences between the SARS-CoV strains were
above two orders of magnitude concerning the necessary
dose.
Possible reasons for this observation might be biological
and biochemical differences between the coronavirus
strains. However, comparing the experimental details,
two other potential dominant factors attract attention:
1. The necessary irradiation doses are lower for viruses
on surfaces, aerosols and pure salt solutions. When
irradiation experiments were performed with the virus
in different solutions, it is important to bear in mind
that the solutions contain organic materials, e.g.,
blood products or residue from cell culture medium.
These solutions exhibit very high absorption of the
applied UVC radiation, resulting in much lower irradi-
ances for viruses that are deeper inside the sample.
This effect is clearly illustrated in Figure 1B (culture
medium transmission) and by the results of Terpstra
et al. [11]. Those authors were aware of the absorp-
tion of their samples and presented results with
10%- and 30%-virus-containing plasma within the ir-
radiated samples. Although it was the same corona-
virus (transmissible gastroenteritis virus (TGEV)) and
the same experimental setup, the results differ by a
factor of 3.1.
Most authors did not measure the UVC absorption
properties of their biological materials because it was
of no importance for their research task; thus, it is
almost impossible to extract the role of the absorption
in the calculation of the necessary irradiation doses
for a 90% virus reduction. In consequence, the lower
values for the log-reduction doses, mostly from viruses
in salt solutions, surfaces or aerosols, might be a more
realistic approach to determine the true virus log-
reduction dose.
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Table 1: Overview of published and analyzed coronavirus photoinactivation investigations sorted by sample condition
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Heßling et al.: Ultraviolet irradiation doses for coronavirus inactivation ...
(Continued)
Table 1: Overview of published and analyzed coronavirus photoinactivation investigations sorted by sample condition
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2. Several investigators performed their irradiation ex-
periments in microtiter plates (MTPs). This might be-
come a problem if the plates are too close to the irra-
diation source, e.g., in the range of only a few centi-
meters. Besides the risk of heating the sample and
subsequently increased sample evaporation, deter-
mination of the irradiation intensity inside the MTP
wells becomes difficult. The MTP well walls shade the
virus-containing samples from irradiation that does
not originate directly above the well. Hence, the true
irradiation intensity within a well is probably quite low
compared to the intensity measured by a photodetec-
tor at the same distance.
Table 1 states whether a study exhibited one or two of
these complications for the intended log-reduction de-
termination. Actually, all calculated extreme values in
Table 1 seem to be influenced by both complicating
factors, and therefore these 254 nm values [12], [13],
[10] were omitted in the further analysis. The data of the
Berne torovirus [14] were also excluded, because of
structural differences between toroviruses and corona-
viruses [15].
All coronaviruses exhibit a similar structure and a single-
stranded RNA length of about 30 kb, allowing the conclu-
sion that they also feature very similar UVC absorption
and UVC disinfection properties. It is therefore justified
to consider all coronaviruses alike in terms of the inves-
tigated UVC-based log-reduction and to summarize the
individual results.
This leads to a total UVC median log-reduction dose of
10.6 mJ/cm2(average 11.9±11.4 mJ/cm2) These values
were calculated without the torovirus data and outliers,
but the input included viruses in media that probably had
higher UVC absorption, leading to reduced photoinactiva-
tion. Therefore, this 10.6 mJ/cm2is probably not the real
value for the log-reduction dose, but instead could be
considered as an upper limit.
Recalculation of the UVC log-reduction dose without using
results from higher-absorption media should lead to more
realistic values. In this case, the total median log-
reduction dose would be 3.7 mJ/cm2(average 5.8±5.5
mJ/cm2).
This overview covers all coronaviruses and both UVC
wavelengths (222 nm and 254 nm), but without results
obtained from studies with probably high absorption
media. The obtained results agree well with UVC inactiva-
tion data for other ssRNA viruses, such as influzenza A
with log-reduction doses around 2 mJ/cm2[5] or the
ssRNA bacteriophage MS2 with log-reduction doses of
about 20 mJ/cm2[5].
So far, most instances of successful coronavirus inactiva-
tion have been performed using mercury vapor lamps
with peak emission at 254 nm. To reduce the use of the
toxic mercury, it seems possible that these vapor lamps
will be replaced in the future by 222-nm excimer lamps
or by 270-nm LED. Since the RNA absorption strengths
are similar, the disinfecting effect at these wavelengths
will probably be approximately the same as with mercury
vapor lamps. However, this should be investigated in
more detail in the future, since absorptions in the lipid
envelope might have a larger influence on virus inactiva-
tion than currently assumed.
Because there are only single results available for the
effect of 365 nm (UVA) and daylight, the focus of this
analysis is on UVC coranavirus inactivation. Both irradi-
ation methods demonstrated a virus reduction, albeit
seemingly much less effective than that achieved with
254 nm irradiation. Nevertheless, these longer wave-
lengths might also be of future interest because their
absorption in samples with organic materials is much
lower, resulting in higher penetration depths which may
allow virus inactivation of larger volumes.
Conclusion
To date, UVC radiation has been effective against all
coronaviruses in all published investigations, although
the absorption properties of the sample media reduced
inactivation success. The calculated upper limit for the
log-reduction median dose (in low-absorbance media) is
10.6 mJ/cm2, but the probably more precise estimation
is 3.7 mJ/cm2.
These results were obtained by investigations on many
different coronaviruses, including SARS-CoV and MERS-
CoV, but not SARS-CoV-2. Nevertheless, it can be as-
sumed that they are also applicable for SARS-CoV-2 and
all future mutations. RNA mutations might have a strong
influence on the pathogenicity of a virus, but they do not
result in larger structural differences, especially concern-
ing the UV absorption properties of the RNA, which are
the main cause for the antiviral effect of ultraviolet radi-
ation.
The above-mentioned log-reduction doses are in the same
order of magnitude or even smaller than log-reduction
doses for other important pathogens, such as Staphylo-
coccus aureus,Escherichia coli,Klebsiella pneumonia
or Candida albicans [5]. They are also low compared to
UVC irradiation recommendations, for instance, the inter-
national standard for UV disinfection of drinking water
[16] with its recommended irradiation dose of 40 mJ/cm2.
Therefore, it can be concluded that existing UVC disinfec-
tion systems and procedures will be sufficient to deal
with all coronaviruses, including SARS-CoV-2.
Notes
Competing interests
The authors declare that they have no competing in-
terests.
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Corresponding author:
Prof. Dr. Martin Heßling
Institute of Medical Engineering and Mechatronics, Ulm
University of Applied Sciences, Albert-Einstein-Allee 55,
89081 Ulm, Germany
Martin.Hessling@thu.de
Please cite as
Heßling M, Hönes K, Vatter P, Lingenfelder C. Ultraviolet irradiation
doses for coronavirus inactivation – review and analysis of coronavirus
photoinactivation studies. GMS Hyg Infect Control. 2020;15:Doc08.
DOI: 10.3205/dgkh000343, URN: urn:nbn:de:0183-dgkh0003436
This article is freely available from
https://www.egms.de/en/journals/dgkh/2020-15/dgkh000343.shtml
Published:
2020-05-14
Copyright
©2020 Heßling et al. This is an Open Access article distributed under
the terms of the Creative Commons Attribution 4.0 License. See license
information at http://creativecommons.org/licenses/by/4.0/.
8/8GMS Hygiene and Infection Control 2020, Vol. 15, ISSN 2196-5226
Heßling et al.: Ultraviolet irradiation doses for coronavirus inactivation ...
... notamment en ce qui concerne les propriétés d'absorption des UV de l'ARN, principal mécanisme de l'effet antiviral des rayons UV[35]. Filtres HEPA (high-efficiency particulate air filters)Les filtres HEPA sont capables d'éliminer 99. ...
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JUMA 24 JUMA Novembre 2020-N°00 S SA AR RS S-C Co oV V-2 2 : : D Di is st ta an nc ce e h ho or ri iz zo on nt ta al le e e et t p pr ro ob ba ab bi il li it té é d de e t tr ra an ns sm mi is ss si io on n p pa ar r a aé ér ro os so ol ls s.. Résumé Devant l'évolution exponentielle de la pandémie SARS-CoV-2, l'Organisation Mondiale de la Santé recommande l'utilisation des masques et une distanciation physique de 1 à 2 mètres. Cependant, ces recommandations semblent insuffisantes devant la distance horizontale parcourue par les gouttelettes, qui peut dépasser les 2,5 mètres. Par ailleurs, le risque de contamination par aérosols n'est pas exclu. Des mesures et moyens physiques supplémentaires sont donc nécessaires pour réduire la transmission virale, surtout dans les milieux confinés. M M. .A A.. H Hi im me eu ur r ; ; E EL L. .M M.. N Ne eb bc ch hi i L La ab bo or ra at to oi ir re e d de e B Bi io op ph hy ys si iq qu ue e, , U Un ni iv ve er rs si it té é A Al lg ge er r 1 1, , F Fa ac cu ul lt té é d de e M Mé éd de ec ci in ne e m ma a. .h hi im me eu ur r@ @u un ni iv v-a al lg ge er r. .d dz z d dr r. .h hi im me eu ur r@ @g gm ma ai il l. .c co om m Summary A head of the exponential development of the SARS-CoV-2 pandemic, the World Health Organization recommends the use of masks and a physical distance of 1 to 2 meters. However, these recommendations seem insufficient with the horizontal distance travelled by droplets, which can exceed 2.5 meters. By elsewhere, the riCovid-19: De L'infection a La Vasculariteluded. Additional measures and physical means are therefore necessary to reduce viral transmission, especially in confined areas.
... The whole process can be performed automatically for disinfecting liquids, surfaces, air and rooms, and it is energy efficient. Previous studies have shown that UV radiation is effective against coronaviruses, and the inactivation of SARS-CoV-2 by UV irradiation may be a reliable method (15,16). Please note that the goggles must be replaced on time after effective disinfection and repeated multiple uses. ...
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Introduction During COVID-19, some front-line personnel experienced varying degrees of eye discomfort due to the use of goggles repeatedly disinfected with chlorine-containing disinfectant. Methods The eye damage information of 276 front-line personnel who used goggles in a hospital from October 1, 2021, to December 1, 2021, was collected by filling out a questionnaire. To study the effect of chlorinated disinfectants on goggles, we immersed the goggles in the same volume of water and chlorinated disinfectant buckets. We tested the light transmittance, color and texture, and airtightness of the goggles at different times (1, 3, 12, 24, 36, 48, 60, 72, 96, 120, 144, 168, 192, 216, 240, and 268 h). In addition, we detected where chlorinated disinfectant remained in the goggles by using disinfectant concentration test paper. Results 60 (21.82%) people experienced dry eyes, stinging pain, photophobia and tearing, conjunctival congestion, eyelid redness, and swelling. After treatment or rest, the patient's ocular symptoms were significantly relieved within 3 days. With the extension of disinfection time, the light transmission of the lenses gradually decreased, and the light transmission reduced when immersion occurred at 216 h. After 72 h of disinfection, the color of the goggle frame began to change to light yellow, the texture gradually became hard and brittle, and the color became significantly darker at 268 h of disinfection. The airtightness of the goggles began to decrease after 168 h of disinfection, the airtightness decreased substantially at 268 h, and the shape changed significantly. In addition, the concentration test paper results show that the disinfection solution mainly resides in the goggle frame seam and goggles' elastic bands' bundle. Conclusions Repeated chlorine disinfectant disinfection will reduce the effectiveness of goggles protection and damage front-line personnel's eye health.
... - In this section, the specifications of the UV sterilization system are determined. The UV dose required for the inactivation of SARS-CoV-2 was reported to be approximately 0.01 J/cm 2 (=10 mJ/cm 2 ) in previous studies [35,36]; therefore, a UV dose of 10 mJ/cm 2 was used in this study. ...
Article
In this study, we develop a system to provide information on the sterilization of baggage carts and arriving passenger baggage to airport (Hereafter referred as arrival baggage) by using ultraviolet (UV) sterilization and information communication technology as border quarantine measures at airports. This system sterilizes arrival baggage and baggage carts by UV irradiation, and allows passengers to easily view the sterilization information recognized by radio frequency indentation technology. This is to provide safety and security not only to passengers, but also to staff, who may come into direct contact with the arrival baggage, of airport, airline, customs, and so on. In addition, the passengers can be provided with baggage tracking information, such as the current location and estimated delivering time of the baggage. This makes it possible to keep social distancing at baggage claims as an infection prevention. Furthermore, we verify the feasibility of the developed system and identify the issues to be addressed for its practical application through a demonstration of proof of concept at Central Japan International Airport.
... Most UV-C systems make use of UV-C with a wavelength of 254 nm, which is harmful to skin and eyes and therefore, should not be used in the vicinity of people. UV-C with a wavelength of 222 nm, on the other hand, is not harmful to people, and has shown to be effective in inactivating, for example, SARS (severe acute respiratory syndrome) and MERS (Middle East respiratory syndrome), 96,97 but is as far as is known not yet available on the market. What is important to note, is that UV-lights can only deactivate the pathogens that they can 'see'. ...
Article
Because of COVID-19, the indoor environmental quality (IEQ) in sports facilities has been a concern to environmental health practitioners. To develop an overall understanding of the available guidelines and standards and studies performed on IEQ in sports facilities, an extensive literature study was conducted, with the aim of identifying: (1) indicators that are being used to assess IEQ in different sports facilities; (2) indicators that are potentially interesting to be used to assess indoor air, in particular; (3) gaps in knowledge to determine whether sports facilities are safe, healthy and comfortable for people to stay and perform their activities. The outcome indicates that most current standards and previous investigations on IEQ in sports facilities mainly focused on dose-related indicators (such as ventilation rate), while building-related indicators (such as ventilation regime) and occupant-related indicators (such as IEQ preferences) were rarely considered. Little attention is given to the fact that ventilation systems may play an important role in the air quality of the location, and few investigations have been performed on the transmission of SARS-CoV-2. This study recommends more research into both occupant and building-related indicators as well as cross-modal effects between various IEQ factors for developing future standards on sports facilities.
... Air filtration (e.g., HEPA) and disinfection (e.g., ultraviolet [UV] irradiation) may contribute to cleaner air in the treatment and examination areas (Lateef 2009;Long et al. 2020;Woolard, Borron, and Mackay 2016). Research has indicated that the UV disinfection procedures are effective in inactivating coronavirus (Heßling et al. 2020). A recent study examined a new portable air recirculation system including HEPA filtration, zirconium-based photochemical oxidation, and germicidal UV irradiation. ...
... Ultraviolet-C (UV-C) radiation may be used to inactivate coronaviruses effectively (240,(248)(249)(250). It acts mainly by photochemical conversions of heterocyclic bases in the structure of nucleic acids without spontaneous reversion (251)(252)(253). ...
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The respiratory coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) quickly developed into a pandemic (1). Even though laboratory diagnostic tests and vaccines were consequently developed (2, 3), the exploration of rapidly deployable, more reliable tools for addressing the current and future pandemics was vital. Toward this goal, researchers worldwide evaluated the use of medical detection dogs as a rapid, reliable and cost-effective screening method for SARS-CoV-2 infections (4). The ability of dogs to distinguish diseases by their high-resolution sense of smell is based on the volatile organic compound (VOC)-hypothesis (5). Numerous infectious and non-infectious diseases change metabolic processes releasing characteristic VOC-patterns in the form of an “olfactory fingerprint” (6–10). Many studies have shown that dogs can detect metabolic disorders, such as cancer (11) and hypoglycemia (12), predict epileptic seizures (13, 14), or even distinguish various pathogens (8, 15–17). Approximately 78% of the 27 SARS-CoV-2-canine detection studies reviewed by Meller et al. yielded > 80% sensitivity and approximately 60% of studies yielded > 95% of specificity (4), highlighting the potential of the dog as a “diagnostic system” and its recommendation for certain settings. Despite these promising results, all studies published up to now differed in numerous design features. They were mostly designed as pilot studies and case-control selection of patients was mostly favored over a more preferable cross-sectional (“cohort”) selection [study quality assessment was conducted and presented by Meller et al. (4)]. The aim of this comprehensive review summary is to provide a general overview of the divergent aspects that may impact canine disease detection and to provide recommendations for future deployment of medical detection dogs (see also summary in Table 1). Specific emphasis is placed on the choice of dogs, training paradigms, safety aspects, sample characteristics, pre-screen processing (e.g., inactivation), and screening-population and its environment related aspects, respectively (see also Figure 1 and Supplementary Figure 1), providing an outlook and proposals for the future standardization in the use of dogs for disease detection. Ultimately, this report provides a blueprint for the potential use of medical detection dogs in future epidemics and pandemics.
... The decrement value may seem to be small, but we are talking about micro-organisms that are very sensitive to the disinfection dose, as each type has its exposure dose, and in case of any decrement in this dose, the disinfection process may not be achieved. [16][17][18] As long as the tilt degree increases, the increment in irradiance rises to 29% from the expected value at 0 ○ . Figure 4 shows the irradiance distribution differences along the irradiated area in two cases, 0 ○ and 20 ○ . ...
Article
Periodically testing the performance of any biological safety cabinet or other sterilization chambers is mandatory; hence, the importance of evaluating the effects of error factors on this performance arises. Until now, despite the necessity of disinfection against many microorganisms, particularly protection against the current pandemic, international standards for the manufacturing and evaluation of safety cabinets did not recommend testing the ultraviolet C performance inside these safety cabinets. The main aim of this paper is to use the sensitivity coefficient as one of the essential terms in uncertainty evaluation, to study the effect of different distances and tilt angles on the irradiance and, hence, the uniformity inside the cabinet or chamber. It was found that the homogeneity of the distribution of irradiance levels along the irradiated area was significantly affected by the distance and angle. The results obtained utilizing the sensitivity coefficient indicated that a simple increase in distance will result in a considerable loss in the irradiance value reaching around 30%. Every 5° increment in the tilt angle causes a decrement in the irradiance value by about 14% compared to the original value (0°); hence, the uniformity decreased significantly by around 45%. These effects may reflect on the sterilization performance of the cabinet as an essential process. At the end of this paper, due to the importance of considering these measurements and the effect of the two parameters on irradiance and, hence, the uniformity, the author recommends that these measurements be added to international standards for safety cabinets manufacturing and evaluation. The recommendation may help to focus more on evaluating the ultraviolet C homogeneity performance inside biosafety cabinets.
... A special effort has been made to determine the ultraviolet susceptibility of different viruses such as SARS-CoV-2, MERS-CoV, and Ebola [3,4]. Here, AlGaN-based deep ultraviolet light emitting diodes (DUV-LEDs) are the current approaches for developing germicidal radiation devices [5]. DUV-LEDs have been developed using nitrides [1,6] due to the wide bandgap [7] and different advantages such as low power, small size with higher efficiency, and wavelength tunability [8]. ...
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In this work, an AlGaN-based Deep-Ultraviolet Light-Emitting Diode structure has been designed and simulated for the zincblende and wurtzite approaches, where the polarization effect is included. DFT analysis was performed to determine the band gap direct-to-indirect cross-point limit, AlN carrier mobility, and activation energies for p-type dopants. The multiple quantum wells analysis describes the emission in the deep-ultraviolet range without exceeding the direct-to-indirect bandgap cross-point limit of around 77% of Al content. Moreover, the quantum-confined Stark effect on wavefunctions overlapping has been studied, where Al-graded quantum wells reduce it. Both zincblende and wurtzite have improved electrical and optical characteristics by including a thin AlGaN with low Al content. Mg and Be acceptor activation energies have been calculated at 260 meV and 380 meV for Be and Mg acceptor energy, respectively. The device series resistance has been decreased by using Be instead of Mg as the p-type dopant from 3 kΩ to 0.7 kΩ.
... Most currently available literature on UV dose for microbial inactivation for static (e.g., surface, liquid) or dynamic (e.g., air) scenarios recorded UV dose on a 2-D scale (i.e., energy per unit area, in mJ/cm 2 or J/cm 2 ) [20,21] using the Bolton and Linden equation (2003) [22] as shown as Equation (1) below. Bolton and Linden proposed the term UV dose to describe the total UV radiant energy absorbed per unit area: ...
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Since the COVID-19 pandemic, improving indoor air quality (IAQ) has become vital for the public as COVID-19 and other infectious diseases can transmit via inhalable aerosols. Air cleaning devices with filtration and targeted pollutant treatment capabilities can help improve IAQ. However, only a few filtration/UV devices have been formally tested for their effectiveness, and little data is publicly available and UV doses comparable. In this research, we upgraded a particulate matter (PM) air filtration prototype by adding UV-C (germicidal) light. We developed realistic UV dose metrics for fast-moving air and selected performance scenarios to quantify the mitigation effect on viable airborne bacteria and PM. The targeted PM included total suspended particulate (TSP) and a coarse-to-fine range sized at PM10, PM4, PM2.5, and PM1. The PM and viable airborne bacteria concentrations were compared between the inlet and outlet of the prototype at 0.5 and 1.0 m3/s (low and high) air flow modes. The upgraded prototype inactivated nearly 100% of viable airborne bacteria and removed up to 97% of TSP, 91% of PM10, 87% of PM4, 87% of PM2.5, and 88% of PM1. The performance in the low flow rate mode was generally better than in the high flow rate mode. The combination of filtration and UV-C treatment provided ‘double-barrier’ assurance for air purification and lowered the risk of spreading infectious micro-organisms.
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Background The viability and virulence of COVID-19 are complex in nature. Although the relationship between environmental parameters and COVID-19 is well studied across the globe, in India, such studies are limited. This research aims to explore long-term exposure to weather conditions and the role of air pollution on the infection spread and mortality due to COVID-19 in India. Method District-level COVID-19 data from April 26, 2020 to July 10, 2021 was used for the study. Environmental determinants such as land surface temperature, relative humidity (RH), Sulphur dioxide (SO2), Nitrogen dioxide (NO2), Ozone (O3), and Aerosol Optical Depth (AOD) were considered for analysis. The bivariate spatial association was used to explore the spatial relationship between Case Fatality Rate (CFR) and these environmental factors. Further, the Bayesian multivariate linear regression model was applied to observe the association between environmental factors and the CFR of COVID-19. Results Spatial shifting of COVID-19 cases from Western to Southern and then Eastern parts of India were well observed. The infection rate was highly concentrated in most of the Western and Southern regions of India, while the CFR shows more concentration in Northern India along with Maharashtra. Four main spatial clusters of infection were recognized during the study period. The time-series analysis indicates significantly more CFR with higher AOD, O3, and NO2 in India. Conclusions COVID-19 is highly associated with environmental parameters and air pollution in India. The study provides evidence to warrant consideration of environmental parameters in health models to mediate potential solutions. Cleaner air is a must to mitigate COVID-19.
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A direct approach to limit airborne transmission of pathogens is to inactivate them within a short time of their production. Germicidal ultraviolet light (UV), typically at 254 nm, is effective in this context, but it is a health hazard to the skin and eyes. By contrast, far-UVC light (207-222 nm) efficiently kills pathogens without harm to exposed human cells or tissues. We previously demonstrated that 222-nm UV light efficiently kills airborne influenza virus (H1N1); here we extend the far-UVC studies to explore efficacy against human coronaviruses from subgroups alpha (HCoV-229E) and beta (HCoV-OC43). We found that low doses of, respectively 1.7 and 1.2 mJ/cm ² inactivated 99.9% of aerosolized alpha coronavirus 229E and beta coronavirus OC43. Based on these results for the beta HCoV-OC43 coronavirus, continuous far-UVC exposure in public locations at the currently recommended exposure limit (3 mJ/cm ² /hour) would result in 99.9% viral inactivation in ~ 25 minutes. Increasing the far- UVC intensity by, say, a factor of 2 would halve these disinfection times, while still maintaining safety. As all human coronaviruses have similar genomic size, a key determinant of radiation sensitivity, it is realistic to expect that far-UVC light will show comparable inactivation efficiency against other human coronaviruses, including SARS-CoV-2.
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Background: Emerging viruses like severe acute respiratory syndrome coronavirus (SARS-CoV), Crimean-Congo haemorrhagic fever virus (CCHFV) and Nipah virus (NiV) have been identified to pose a potential threat to transfusion safety. In this study, the ability of the THERAFLEX UV-Platelets and THERAFLEX MB-Plasma pathogen inactivation systems to inactivate these viruses in platelet concentrates and plasma, respectively, was investigated. Materials and methods: Blood products were spiked with SARS-CoV, CCHFV or NiV, and then treated with increasing doses of UVC light (THERAFLEX UV-Platelets) or with methylene blue (MB) plus increasing doses of visible light (MB/light; THERAFLEX MB-Plasma). Samples were taken before and after treatment with each illumination dose and tested for residual infectivity. Results: Treatment with half to three-fourths of the full UVC dose (0·2 J/cm2 ) reduced the infectivity of SARS-CoV (≥3·4 log), CCHFV (≥2·2 log) and NiV (≥4·3 log) to the limit of detection (LOD) in platelet concentrates, and treatment with MB and a fourth of the full light dose (120 J/cm2 ) decreased that of SARS-CoV (≥3·1 log), CCHFV (≥3·2 log) and NiV (≥2·7 log) to the LOD in plasma. Conclusion: Our study demonstrates that both THERAFLEX UV-Platelets (UVC) and THERAFLEX MB-Plasma (MB/light) effectively reduce the infectivity of SARS-CoV, CCHFV and NiV in platelet concentrates and plasma, respectively.
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The objective of this study was to evaluate the effectiveness of the SurePure Turbulator ultraviolet-C (UV-C, 254 nm wavelength) irradiation equipment on inactivation of different enveloped and non-enveloped viruses in commercially collected liquid animal plasma. Specifically, Pseudorabies virus (PRV), Porcine reproductive and respiratory syndrome virus (PRRSV), Porcine epidemic diarrhea virus (PEDV), Bovine viral diarrhea virus (BVDV), Classical swine fever virus (CSFV), Swine influenza virus (SIV) as enveloped viruses and Porcine parvovirus (PPV), Swine vesicular disease virus (SVDV), Porcine circovirus type 2 (PCV-2) and Senecavirus A (SVA) as non-enveloped viruses, were inoculated in bovine or porcine plasma and subjected to different UV-C irradiation doses (0, 750, 1500, 3000, 6000 and 9000 J/L) using an UV-C device developed for opaque liquid working under turbulent flow. The enveloped viruses tested were inactivated at < 3000 J/L of UV-C, being the dose needed to inactivate 4 log TCID50 (4D) of 1612 J/L for PRV,1004 J/L for PRRSV, 1953 J/L for PEDV, 1639 J/L for SIV, 1641 J/L for CSFV and 1943 J/L for BVDV. The non-enveloped viruses tended to have higher 4D values: 2161 J/L for PPV, 3223 J/L for SVA and 3708 J/L for SVDV. Because the initial viral concentration was <4.0 Log for PCV-2, it was not possible to calculate the 4D value for this virus. In conclusion, these results demonstrated that the SurePure Turbulator UV-C treatment system is capable of inactivating significant levels of swine viruses inoculated in commercially collected porcine or bovine plasma. It was concluded that irradiation with UV-C can provide an additional redundant biosafety feature in the manufacturing process of spray-dried animal plasma.
Chapter
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Ultraviolet Germicidal Irradiation (UVGI) is electromagnetic radiation that can destroy the ability of microorganisms to reproduce by causing photochemical changes in nucleic acids. Wavelengths in the UVC range are especially damaging to cells because they are absorbed by nucleic acids. The germicidal effectiveness of UVC peaks at about 260–265 nm. This peak corresponds to the peak of UV absorption by bacterial DNA. The germicidal effectiveness of UVC radiation can vary between species and the broader range wavelengths that include UVB also make a small contribution to inactivation (Webb and Tuveson 1982). Although the methods and details of disinfection with ultraviolet light are fairly well understood, to the point that effective disinfection systems can be designed and installed with predictable effects, the exact nature of the effect of ultraviolet light on microorganisms at the molecular level is still a matter of intensive research. This chapter examines the fundamentals of the complex interaction between UV irradiation and cell DNA at the molecular level and provides detailed background information to aid in the understanding of the various biophysical processes that are involved in microbial inactivation.
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To evaluate the virucidal efficacy of six commonly used chemical disinfectants, and ultraviolet radiation (U.V.) against SARS-CoV and compare it to the resistance of other airborne viruses, such as Influenza and Respiratory Sincytial Virus, a salt solution containing a standard concentration of cell-grown viruses, was mixed with a larger volume of different disinfectants at their use dilution and the mixtures were held for a defined contact time. The virucidal efficacy of disinfectants and U.V. was evaluated by infectivity, detected by inoculation of samples in suitable cell culture and genome integrity, detected by nested RT-PCR. SARS-CoV as well as RSV seem to be sensible to the different disinfectants tested in our study and U.V. radiation, while influenza virus appear to be more resistant in particular to the action of chlorhexidine digluconate and benzalkonium-chloride. In consideration of the possible infectious role of SARS-CoV RNA, sodium hypochlorite 0.1% appear to be the more efficacious disinfectant for surfaces and hands potentially contaminated with respiratory viruses and SARS-CoV.
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With the outbreak of unknown pneumonia in Wuhan, China, in December 2019, a new coronavirus, Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), aroused the attention of the entire world. The current outbreak of infections with SARS-CoV-2 is termed Coronavirus Disease 2019 (COVID-19). The World Health Organization declared COVID-19 in China as a Public Health Emergency of International Concern. Two other coronavirus infections-SARS in 2002-2003 and Middle East Respiratory Syndrome (MERS) in 2012-both caused severe respiratory syndrome in humans. All 3 of these emerging infectious diseases leading to a global spread are caused by β-coronaviruses. Although coronaviruses usually infect the upper or lower respiratory tract, viral shedding in plasma or serum is common. Therefore, there is still a theoretical risk of transmission of coronaviruses through the transfusion of labile blood products. Because more and more asymptomatic infections are being found among COVID-19 cases, considerations of blood safety and coronaviruses have arisen especially in endemic areas. In this review, we detail current evidence and understanding of the transmission of SARS-CoV, MERS-CoV, and SARS-CoV-2 through blood products as of February 10, 2020, and also discuss pathogen inactivation methods on coronaviruses.
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BACKGROUND Ebola virus (EBOV) and Middle East respiratory syndrome coronavirus (MERS‐CoV) have been identified as potential threats to blood safety. This study investigated the efficacy of the THERAFLEX UV‐Platelets and THERAFLEX MB‐Plasma pathogen inactivation systems to inactivate EBOV and MERS‐CoV in platelet concentrates (PCs) and plasma, respectively. STUDY DESIGN AND METHODS PCs and plasma were spiked with high titers of cell culture–derived EBOV and MERS‐CoV, treated with various light doses of ultraviolet C (UVC; THERAFLEX UV‐Platelets) or methylene blue (MB) plus visible light (MB/light; THERAFLEX MB‐Plasma), and assessed for residual viral infectivity. RESULTS UVC reduced EBOV (≥4.5 log) and MERS‐CoV (≥3.7 log) infectivity in PCs to the limit of detection, and MB/light decreased EBOV (≥4.6 log) and MERS‐CoV (≥3.3 log) titers in plasma to nondetectable levels. CONCLUSIONS Both THERAFLEX UV‐Platelets (UVC) and THERAFLEX MB‐Plasma (MB/light) effectively reduce EBOV and MERS‐CoV infectivity in platelets and plasma, respectively.
Article
Efficient and automated methods of disinfecting surfaces contaminated with the Middle Eastern respiratory syndrome coronavirus (MERS-CoV) may prevent the spread of the virus. Here we report the efficacy and use of an automated triple-emitter whole room UV-C disinfection system to inactivate mouse hepatitis virus, strain A59 (MHV-A59) and MERS-CoV viruses on surfaces with a >5 log 10 reduction. Infect. Control Hosp. Epidemiol. 2016;1–2