FACE MASK FOR PROTECTION AGAINST VIRAL OR BACTERIAL INFECTIONS

Description

[0001] The present invention relates generally to biomedical engineering and, more specifically, to an anti-epidemic protective mask and its manufacture. In preferred embodiments, the protective mask serves to shield the face from viral and bacterial infections, particularly coronaviruses, which are increasingly prevalent in hospitals and other hotspots. Furthermore, the invention can also be advantageously used for the treatment of chronic diseases or to shorten the recovery time for temporary respiratory illnesses.

[0002] It is well known that massive problems arise in the fight against pandemics caused by viral respiratory infections, such as the coronavirus COVID-19, Severe Acute Respiratory Syndrome (SARS), Middle East Respiratory Syndrome (MERS), Spanish Flu (H1N1), Swine Flu (H1N1 / 09 ​​virus), or Human Rhinovirus (HRV). Currently, attempts are being made to combat the spread of these infections as quickly as possible with the help of appropriate vaccines and medications [1] or through comprehensive precautionary measures such as quarantine or the introduction of general social distancing regulations for the population. In addition, biomedical instruments such as intelligent body temperature detectors and various hygiene solutions such as masks, injection needles, and ventilators are being provided for the identification and treatment of viral infections [2-4].

[0003] Various solutions for face masks are known from the state of the art. For example, [5] presented face shields made of plastic-coated materials combined with charcoal substances, produced using 3D printing processes, intended to prevent an outbreak of the coronavirus.

[0004] Furthermore, [6, 7] proposed a face mask made of a material coated with sodium chloride salt, which can achieve decontamination within 5 minutes, killing long-lived organisms on its outer surface. However, this time for disinfection of the outermost surface of the mask is considered too time-consuming.

[0005] State-of-the-art filter masks used for personal protective equipment, such as surgical or N90, N95, and N100 protective masks, do not filter or block very small particles (≤ 0.1 pm). They are typically constructed from natural wool fibers and multilayer nonwoven fabrics made of plastic-based fabrics such as polypropylene, polystyrene, polycarbonate, polyethylene, or polyester with a mesh size of approximately 1 µm. In contrast, biological / chemical protective masks usually contain Ag-doped particles

[15] . The filtering principles are based on the deflection of large particles from the air and their adhesion to the fiber. The finer particles (<0.1 pm) collide during the flow due to the diffusion path and thus adhere to the fibers. In addition, electrostatically charged fibers are used to attract oppositely charged particles.Even when UV-catalyzed agents are added to the mask structure, an additional filter arrangement with the smallest possible pore size is used in practice, either as an additional filter element or as a filter fabric integrated into the photocatalytic agent. This can serve to improve the filter function by disinfecting any microorganisms that may be trapped in the fabric or that may have escaped. Therefore, extremely fine porous filters are the first requirement, but these cause communication and / or breathing difficulties and, if clogged or contaminated, require filter replacement.

[0006] Other air filter masks suitable for different functions are disclosed in [8-11].

[0007] However, all of these solutions are unsuitable for viral or bacterial disinfection of the air we breathe.

[0008] It is also known that photocatalytic coatings, such as TiO 2 , are used in combination with UV radiation to disinfect medical devices and operating rooms in hospitals equipped with so-called self-cleaning surfaces [12, 13].

[0009] Due to its large band gap energy of 3.2 eV, TiO2 is capable of absorbing short-wave radiation, such as UV light. This photoactivation excites the electrons in the outermost shell of TiO2 to mobilize, creating electron-hole pairs. When the excited electrons collide with the outer shell electrons of oxygen or H2O molecules, decomposition occurs, leading to the hydroxylation and ionization of these molecules. The resulting radicals are also unstable, and when they come into contact with microorganisms, they peroxidize them and destroy their nucleic acids, thus halting their replication and destroying them.

[0010] Various approaches to developing self-cleaning masks against toxins are based on these findings, allowing them to be used, for example, in bushfire control and in war, but also in biologically contaminated areas, particularly for combating viral or microbial epidemics. In particular, paper face masks have been impregnated with a TiO2 solution that can be activated by sunlight or fluorescent light sources. A mask prepared in this way degrades toxins such as formaldehyde and the like when used for medical purposes (US Pat. No. 5,744,407).

[0011] Another approach for a single-sided face shield integrates an outlet for exhaled air and cartridges with two stacked filter elements for inhaled air into the mask (US 2015 / 0114397 A1). The inner filter element is designed as a honeycomb mesh substrate consisting of an aluminum grid or aluminum pad with a grid, with mesh openings up to 180 µm in size, and coated with TiO2. This element is photocatalytically activated by UV light in the wavelength range 240-280 nm. The outer filter element is an activated carbon filter or a filter with silver nanoparticles.

[0012] Another proposal for disposable head protection consists of several components, such as carbon filters, a nanoscale photocatalytic titanium dioxide mesh activated by a built-in UV lamp, and a nano-silver ion filter (CN 1 03 656 908 A). This complex configuration is advantageous for ensuring the purification and simultaneous disinfection of the breathing air.

[0013] In addition to the disposable function, however, a lead layer is used to shield against UV rays, which is disadvantageous due to the health risks. Furthermore, fiberglass material is used to assemble textile fabrics with variable pore sizes and to serve as mask filters for toxins and microbial or bacterial substances, either with or without the integration of UV-catalyzed TiO2 (CN 1 03 656 908 A, US 8 828 129 B2, US 5 720 280).

[0014] DE 10 2007 034 879 A1 describes a filter element based on the combination of a porous carrier material with light-conducting properties with a photoactive substance. The proposed carrier materials are polymers, polymer blends, or fibers. The coating is intended to inactivate microorganisms even with pore diameters of up to 10 µm.

[0015] DE 10 2004 008 931 B4 describes porous glass and porous glass ceramics as biocidal agents, but these are in powder form, not monolithic form.

[0016] US2008083411 A1 discloses a photocatalytically effective respirator mask with integrated LED UV sources.

[0017] An object of the present invention is to overcome the disadvantages explained in the prior art and to provide a reusable, self-disinfecting face mask for protection against viral or bacterial infections with a bidirectional disinfecting effect, with which, on the one hand, healthy people and, on the other hand, the environment of infected people can be protected from the risk of infection.

[0018] According to the invention, this object is achieved with a face mask according to claim 1.

[0019] The face mask serves to protect against viral or bacterial infections. The face mask has at least one inhalation section to cover the mouth and nose region of a user. The inhalation section comprises a composite of at least two translucent or semi-transparent glass layers, wherein the glass layers are designed as porous glass plates and are at least temporarily irradiated by at least one UV-C / A source, which in turn is a component of the face mask.

[0020] The present invention can play a significant role in the current efforts to flatten the curve of the novel coronavirus outbreak worldwide. To this end, a bidirectional face mask is provided that protects a person's respiratory tract and preferably also their eyes from viral infection, and is also reusable and self-disinfecting.

[0021] In contrast to conventional masks used to date, the proposed face mask is not made of textile fabric based on polymers or natural fibers, such as cotton, but rather of porous glass plates coated with a thin, catalytically active layer. The latter can be activated using light in the ultraviolet (UV) wavelength range up to the visible spectral range.

[0022] In contrast to the prior art according to DE 10 2007 034 879 A1, the present invention uses an inorganic monolithic carrier material. Its advantages include, in particular, transparency or translucency, at least in part; short residence times of the not yet deactivated microorganisms; and the possibility of cleaning or regenerating the surfaces after certain periods of use.

[0023] According to a preferred embodiment, the UV-C / A source is arranged circumferentially between the glass layers on the outer contour of the inhalation section. Particularly preferably, the UV-C / A source provides light in the wavelength range 185 nm - 280 nm, with which the glass layers are irradiated. Preferably, the glass layers are selectively coated with photoactive thin films of a transparent conductive oxide (TCO). Particularly preferably, the transparent conductive oxide has a thickness of 50 nm to 1000 nm. Advantageously, the transparent conductive oxide is a doped semiconductor made of TiOx, ZnO, SnO2, and / or SiOx.

[0024] Advantageous embodiments are characterized in that the glass layers are planar or application-specifically shaped and the pores in the glass layers have a size in the range of 1 nm to 1 µm.

[0025] In a preferred embodiment, the outer contour of the inhalation section is covered with an elastic barrier layer made of a material that is at least semi-transparent to UV rays.

[0026] A preferred embodiment of the face mask has an elastic holder with which it can be positioned on the user's head, wherein accumulators for operating the UV-C / A source and / or for heating the TCO layers are preferably integrated into the holder.

[0027] The face mask according to the invention preferably comprises the inhalation section and an eye shield, wherein the inhalation section is preferably designed as a double- or multi-layer structure made of porous, colloidal mesh or textile glass plates. A further developed embodiment carries the transparent eye shield on an upper part of the inhalation section. This eye protection can prevent direct contact of the eyes with infected materials, thereby further increasing the protective effect of the face mask. The eye shield is preferably also surrounded by a barrier layer, in particular made of black silicone.

[0028] In a further preferred embodiment, the inhalation section is produced by etching through holes, so-called aligned pores (pinholes), which can be produced in particular by means of photolithography technology.

[0029] Preferably, the glass layers are selectively coated with photoactive films made of various semiconductors such as TiO 2 / TiO x (also called black titanium dioxide), ZnO, SnO 2 , SiO x , etc., in a preferred thickness of 50 nm to 1000 nm. These semiconductors are in turn preferably doped with elements that have no or only a very small band gap between the valence and conduction bands, e.g., nitrogen, hydrogen, graphene, indium, palladium, boron, among others, so that a thin layer of transparent, electrically conductive oxide (TCO) is formed.

[0030] A further developed embodiment of the face mask also has a humidification source or a moisture generator, which comprises a liquid reservoir and units for transmitting the liquid to the glass layer composite. It is also advantageous if the face mask has one or more units for detecting and stabilizing the temperature and / or humidity of the air inhaled by the user through the inhalation section. This can significantly increase the peroxidation effect and thus the decomposition of viruses or bacteria. Preferably, a short-wave UV-C / A radiation source is coupled to the transparent / translucent glass structure in such a way that it irradiates its entire surface, while the transparent eye shield is shaded by a black barrier. This arrangement can be operated continuously, e.g., in combination with a rechargeable power bank.

[0031] Since the face mask according to the invention acts as bidirectional protection for both infected patients and non-infected persons, it can be used in a variety of ways for many groups of people.

[0032] As already stated, the face mask according to the invention comprises a composite of at least two layers of transparent / translucent glass, which are designed as porous filters with openings of, for example, a few micrometers or fractions thereof. This construction enables air filtration, comfortable breathing, and clear speech transmission at the same time, with the inhalation section of the mask, in particular, being shaped to adapt to the shape of the face and tightly cover the mouth-nose region of the face.

[0033] The inner surface(s) of the inhalation section are coated with photoactive, thin layers of preferably transparent and electrically conductive elements or compounds or oxides, such as TiO x , ZnO, SiO x , etc., which reflect UV-C / A radiation and prevent skin-harmful radiation from penetrating the glass layers. These so-called TCO layers (transparent conducting oxide, transparent metal oxide) also enable the breathing air to be heated using electrical resistance heating, which also positively influences the disinfection effect.

[0034] In a modified version, the photoactive, thin layers additionally contain one or more dopings so that the face of the mask wearer is also protected from UV radiation.

[0035] The resulting photocatalytic effect leads to the decomposition of the H 2 O and O 2 molecules in the inhaled air and generates ionized hydroxyl (OH-) and oxygen (O 2 -) ions on the glass surface, e.g., coated with TiO 2. As a result, peroxidation of organic substances occurs, leading to the destruction of their nucleic acids and DNA chains, which completely destroys and degrades viruses or bacteria; such processes are generally described in [12, 13].

[0036] The UV-C / A light source is preferably arranged circumferentially between the glass filter layers so that light in the preferred wavelength range of 185-280 nm hits the coated glass surfaces and produces the disinfecting effect. A barrier layer (protective layer) is provided in the direction of the eyes to shield the eyes and the area around the eyes from UV radiation.

[0037] In order to reduce manufacturing costs, the previously described coating of the glass layers can be omitted in a modified version of the face mask if the effect of the UV-C / A light source already provides sufficient protection against viral and bacterial infections.

[0038] The outer contour of the inhalation section is surrounded by a barrier layer (protective layer), for example, made of black silicone. This serves to shield the UV-C / A light source, preventing UV light from penetrating to the outside while also providing adequate coverage for the facial area.

[0039] In another embodiment of the face mask, an external humidity generator is also integrated. This generator can be used to supply humidified air to the inhalation section of the face mask. For this purpose, the humidified air is channeled, for example, through a thermally insulated pipe system, penetrates the porous glass layers, and can also coat their surfaces with a film of moisture. Humidifying the air can be particularly beneficial for people with respiratory diseases. For example, in chronic respiratory diseases, predominantly warm and humid air is required for healing. For this purpose, the TCO layers can be specifically activated and electrically heated, thus also warming the humid air.The relative humidity (RH) and the temperature of the air can be determined using humidity sensors and stabilized using a microprocessor-based controller, for example to values ​​of 40%RH and 38°C.

[0040] The face mask can also be used to treat colds, such as coughs or colds, which require relatively cool air (e.g., temperatures between 19-20°C). This is achieved by switching off the electrical heating of the TCO layers and exclusively utilizing the cooling effect created by water evaporation.

[0041] The upper part of the face mask is preferably designed as an eye shield made of a transparent material, such as soda-lime glass, or a plastic, such as polyethylene. The eye shield can also be provided with a protective layer of black silicone to protect against mechanical stress.

[0042] The electrical heating of the TCO layers and the operation of the UV light source are preferably carried out by means of rechargeable batteries (power banks), which can be integrated into a preferably elastic headband or the like or positioned externally.

[0043] In contrast to state-of-the-art face masks, which predominantly use fabrics with fibers based on cellulose, wool, plastics, or glass, the face mask according to the invention consists of porous glass layers that cover the face either flat or pre-shaped for a specific application. These glass layers are structured to be semi-transparent to light and permeable to air. This enables both comfortable breathing and easy communication with the environment. This functionality is largely determined by the porosity of the glass layers. The glass substrate also serves as a carrier for thin coatings of doped electrically semiconducting materials, e.g. TiO 2 , so-called TCO layers (transparent conducting oxide, transparent metal oxide layers), creating a disinfecting and reflective effect; the principles of these effects are described in [13, 14].This effect is achieved by selectively heating the layers and / or by irradiating them with a UV-C / A light source and the associated photocatalytic effect, which ensures sufficient disinfection as the air flows through the face mask. Additional multifunctionality beyond the disinfectant effect, for example, for using the face mask for medical applications, can be achieved by specifically adjusting the surface properties of the glass coatings and additionally supplying humidified air. This is made possible by hydrophilic, i.e., "water-attracting," surface properties (high surface energy), which ensure that the water molecules completely wet the surfaces.The novelty of such a face mask is based on the possibility of targeted functionalization of the porous glass filters by means of the described coatings and in combination with one or more UV light sources and preferably with an external moisture generator, so that the glass layers can be electrically heated, photocatalytically reactivated and preferably hydrophilically wetted.

[0044] The present invention aims to extend the conventional decontamination mechanism, in addition to its self-disinfecting properties, with a self-cleaning mechanism. This is achieved by functionalizing the metal oxide layers, e.g., TCOs. This is due to the hydrophilic behavior of TCOs, which is responsible for the fact that microorganisms do not adhere to these layers. When the glass surfaces are doped, e.g., with N2 or exposed to UV radiation, the TCOs exhibit, in addition to the well-known increased photoactivity, a significantly increased hydrophilicity, also called superhydrophilicity; the basic effects are described in [19, 20]. Consequently, the viruses or bacteria do not settle in the pores, thus causing no blockage, but are destroyed within them.

[0045] Porously structured, translucent or semitransparent glass, which is planar or preformed and functionalized with photocatalytic or TCO coatings, has not been used in practical applications to date. The invention now exploits the possibility of producing porous glass with a pore size of 1 nm to 1 µm and the ability to specifically adapt the shape to specific needs while maintaining its semi-transparency to a certain degree [21, 22] to realize the face mask according to the invention and make it advantageously usable for combating infections and pandemics triggered by viruses such as COVID-19.

[0046] According to a modified embodiment, at least one of the translucent or semi-transparent glass layers consists of a material produced using a sol-gel process. Such materials are also referred to as aerogels and are highly porous solids in which up to 99.98% of the volume is formed by pores. The material produced using the sol-gel process is suitable for the application according to the invention provided the pores have a size in the range of 1 nm to 1 µm and the material is translucent or semi-transparent, i.e., equivalent to glass in order to conduct UV radiation. A silicon-based aerogel is particularly suitable as the material for at least one of the translucent or semi-transparent glass layers. Preferably, one or more aerogel wafers, each several hundred micrometers thick, can be bonded with polymer additives to increase mechanical strength.

[0047] Further details will become apparent from the following description of a preferred embodiment of the invention, with reference to the drawings. They show: Fig. 1 shows a simplified frontal view of a face mask according to the invention worn on the face of a user; Fig. 2 shows a simplified, partially sectioned side view of the user wearing the face mask, as well as a detailed drawing of a section of the face mask in section.

[0048] The Figures 1 and 2show together an embodiment of the face mask according to the invention, which serves to protect against viral or bacterial infections. In this embodiment, the face mask has an inhalation section 10 for covering the mouth-nose region, and an eye shield 7, which is attached to the top of the inhalation section or is integrally formed. In the embodiment shown, the inhalation section 10 is a composite of three translucent or semi-transparent glass layers 2, as shown in the detailed drawing in Fig. 2is clearly visible. The glass layers 2 are equipped with numerous through-holes to allow air to pass through. Furthermore, one or more UV-C / A sources 1 are provided in the edge region between the outer and middle glass layers, which irradiate TiO 2 layers 3 that are applied to the mutually facing surfaces of the outer and middle glass layers 2. Instead, TCO coatings are applied to the mutually facing surfaces of the middle and inner glass layers 2. An air gap 5 remains between the mutually facing surfaces of the glass layers. The total width of this layer arrangement is in the range of 6 to 10 mm. The inhalation section 10 is bordered by a barrier layer 6, which is made of black silicone, for example.

[0049] The present invention combines numerous functions and advantages in a single solution. These include, in particular, the disinfecting and self-cleaning effect (reusability), bidirectional functionality (air filtration during inhalation and exhalation), the ability to provide tempered and humidified breathing air, protection against harmful UV radiation, the avoidance of chemicals for absorption, low power consumption, and the possibility of semi-transparent communication with other people.

[0050] The face mask according to the invention also allows for setting, monitoring, and controlling a defined temperature and relative humidity. Likewise, the humidity of the breathing air and photothermal catalysis can be effectively combined. Finally, the use of UV light sources with different wavelengths is also conceivable.

[0051] All these advantageous properties result in a multifunctional benefit for this face mask according to the invention as an antiviral, anti-chronic cough and anti-nasal congestion mask, as well as a ventilator for infected individuals. A further aspect of the invention thus lies in improved treatment options for chronic or temporary respiratory diseases. Bibliography

[0052] [1] - https: / / www.who.int / [2] - https: / / www.bosch-presse.de / pressportal / de / en / combating-the-coronavirus-pandemic-bosch-develops-rapid-test-for-covid-19-209792.html [3] - https: / / bioengineering.stanford.edu / research / bioecoronavirus-response [4] - https: / / www.openpr.de / news / 1039482 / Hygiene-ist-die-Basis-Livinguard-Technologie-macht-Krankenhaeuser-Haushalte-Co-sicherer.html [5] - https: / / www.controleng.com / articles / universitiesdeveloping-diy-medical-devices-ppe-to-combat-coronavirusspread / [6] - https: / / www.businessinsider.de / international / maskcoated-in-salt-neutralizes-viruses-like-coronavirus-2 02 0-2 / ?r=US&IR=T [7] - Quan, FS, Rubino, I., Lee, SH, Koch, B., & Choi, HJ (2017). Universal and reusable virus deactivation system for respiratory protection. Scientific reports, 7(1), 1-10. [8] - https: / / www.ao-air.com / [9] - https: / / www.globex.co.nz / o2o2-pollution-facewear

[10] - https: / / ifworlddesignguide.com / search?search=mask# / pages / page / entry / 283140-cara-nasal-mask

[11] - https: / / ifworlddesignguide.com / search?search=mask# / pages / page / product / 207-airborne

[12] - Hajkova, P., Spatenka, P., Horsky, J., Horska, I., & Kolouch, A. (2007). Photocatalytic effect of TiO2 films on viruses and bacteria. Plasma Processes and Polymers, 4(S1), S397-S401.

[13] - Rajh, T., Dimitrijevic, N. M., Bissonnette, M., Koritarov, T., & Konda, V. (2014). Titanium dioxide in the service of the biomedical revolution. Chemical reviews, 114(19), 10177-10216.

[14] - TABATABAIE-RAISSI, Ali; MURADOV, Nazim Z.; FAIREY III, Philip W. Photocatalytic face mask. U.S. Patent Nr. 5,744,407, 1998.

[15] - LITZ, Jeffery C. Chemical and biological protection mask. U.S. Patent Application Nr. 13 / 784,062, 2015.

[16] - . Anti-haze mask with nanoscale titanium dioxide photocatalysis net and mini-size air purifier. Nr. CN103656908A, 2013.

[17] - VOLO, Giovanni D.; CARABETTA, Salvatore R. Two-stage air filter and mask incorporating the same. U.S. Patent Nr. 8,828,129, 2014.

[18] - ELSTRAN, Gerald V.; MATTILA, Robert J.; PHILLIPS, Jerome D. Attenuator for use with respirators. U.S. Patent Nr. 5,720,280, 1998.

[19] - Zhu, W., Feng, X., Feng, L., & Jiang, L. (2006). UV-Manipulated wettability between superhydrophobicity and superhydrophilicity on a transparent and conductive SnO2 nanorod film. Chemical Communications, (26), 2753-2755.

[20] - Qi, G., Liu, X., Li, C., Wang, C., & Yuan, Z. (2019). The Origin of Superhydrophobicity for Intrinsically Hydrophilic Metal Oxides: A Preferential O2 Adsorption Dominated by Oxygen Vacancies. Angewandte Chemie International Edition, 58(48), 17406-17411.

[21] - Krenkel, S., Uhlig, H., Enke, D., & Rädlein, E. (2015).Manufacture of highly porous, anisotropic glass monoliths with a honeycomb-like structure. Physics and Chemistry of Glasses-European Journal of Glass Science and Technology Part B, 56(4), 149-158.

[22] - Barascu, A., Kullmann, J., Reinhardt, B., Rainer, T., Roggendorf, H., Dubiel, M., & Enke, D. (2012). Preparation of porous glass monoliths with an aligned pore system via stretch forming. Journal of the American Ceramic Society, 95(10), 3013-3015.

Claims

1. A face mask for protecting against viral or bacterial infections, having at least one UV-C / A source and an inhalation section (10) for covering the nose and mouth region, characterized in that the inhalation section (10) comprises a composite of at least two translucent or semi-transparent glass layers (2), wherein the glass layers (2) are constructed as porous glass plates onto which a thin, catalytically active layer has been applied which can be activated with the aid of light in the ultraviolet wavelength region (UV) extending into the visible region of the spectrum, and wherein the glass layers can be at least temporarily irradiated by the UV-C / A source (1).

2. The face mask as claimed in claim 1, characterized in that the UV-C / A source (1) is disposed circumferentially on the outer contour of the inhalation section (10) between the glass layers (2) and irradiates the glass layers with UV light, preferably in the 185 nm - 280 nm wavelength region.

3. The face mask as claimed in claim 1 or claim 2, characterized in that the glass layers (2) are selectively coated with photoactive thin films produced from a transparent conducting oxide (TCO).

4. The face mask as claimed in claim 3, characterized in that the transparent conducting oxide has a thickness of 50 nm to 1000 nm and is a doped TiOx, ZnO, SnO2 and / or SiOx semiconductor.

5. The face mask as claimed in one of the preceding claims, characterized in that the glass layers (2) are planar in configuration or shaped specifically for the application and the pores have a size of 1 nm to 1 µm.

6. The face mask as claimed in one of the preceding claims, characterized in that the outer contour of the inhalation section (10) is covered with an elastic barrier layer (6) produced from a material which is at least semi-transparent to UV irradiation.

7. The face mask as claimed in one of the preceding claims, characterized in that it has an external humidity generator which comprises a reservoir for liquid and units for transferring the liquid onto the glass layer composite.

8. The face mask as claimed in one of the preceding claims, characterized in that it has units for detecting and stabilizing the temperature and the humidity of the air to be inhaled.

9. The face mask as claimed in one of the preceding claims, characterized in that a transparent eye shield (7) is formed on the upper portion of the inhalation section (10) .

10. The face mask as claimed in claim 9, characterized in that the eye shield (7) is bordered by a barrier layer produced from black silicone (6).

11. The face mask as claimed in one of claims 1 to 10, characterized in that it can be positioned on the head of a user with the aid of an elastic retaining device, wherein power packs for operating the UV-C / A source (1) and optionally for heating the TCO layers are integrated into the retaining device.

12. The face mask as claimed in one of claims 1 to 11, characterized in that at least one of the translucent or semi-transparent glass layers (2) consists of a material produced by means of a sol-gel process.