EP4126080A1

EP4126080A1 - Method for viral disinfection of air and fomites in a defined space

Info

Publication number: EP4126080A1
Application number: EP21715300.6A
Authority: EP
Inventors: Dominique Mercier
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-04-03
Filing date: 2021-04-06
Publication date: 2023-02-08
Also published as: CA3173392A1; FR3108849B1; US20230241276A1; FR3108849A1; WO2021198527A1

Abstract

The invention relates to a method for viral disinfection of a defined space, comprising: diffusing (El), into the ambient air in the defined space, molecular ozone with an exposure dose CT that corresponds to the product of C x T, where C represents the concentration of molecular ozone and T represents the duration of treatment, said exposure dose CT being greater than 2 mg.min/m³, preferably substantially constant and equal to 5 mg.min/m³; and regulating the humidity level of the ozonised ambient air in the defined space.

Description

Viral disinfection process for air and fomites in a defined space

The present invention relates to the field of viral disinfection of defined spaces, in particular confined spaces, such as the interior volume of premises, of decontamination airlocks (in particular before accessing a confined space), of goods transport vehicles or passengers, such as train cars for example, or even smaller volumes of spacesuit chambers or other antiviral protective gear.

The invention thus aims to allow the effective disinfection of confined spaces and thus eliminate at least some of the drawbacks associated with the techniques currently proposed.

The present invention relates more specifically to a method for viral disinfection of the ambient air of such defined spaces and associated fomites. The present invention also provides various embodiments of systems capable of implementing such a method.

It is specified that the expression “associated fomites” should be understood here to mean surfaces, materials or objects contaminated by one or more viruses, and liable to contaminate other objects, animals or people, thus playing a role. role in the spread of contagious viral disease. For example, these fomites can consist of surfaces of tables, seats or any other mobile or fixed object contained in the defined space considered.

In addition, it should be understood here, within the meaning of the invention, that a defined space corresponds either to a space capable of being substantially isolated in order to avoid an uncontrolled leakage of the interior air that it contains - we are talking about here in a confined or closed space, or to a defined volume in which moving air (continuous or batch) is exposed during a given time to one or more treatments, on the principle of a treatment chamber of a air flow as for respiratory protection or the treatment of air distribution ducts in a room.

The present invention is thus intended to allow the inactivation of viruses suspended in the air and / or, where appropriate, deposited on fomites present in defined spaces as illustrated above, as well as in the aeraulic and climatic installations which are associated with them for the renewal of hygienic air and / or thermal comfort.

STATE OF THE ART

It is known from the state of the art the possibility of carrying out the viral disinfection of fomites by the use of virucidal products, either by manual application (a), or by air (b), or by the use of germicidal UVC radiation (c).

Following (a) and (b), virucidal products are applied by contact or spraying on the surfaces to be treated, the different materials making up the surfaces to be treated often requiring the use of different virucides. However, indoor air often carries so-called airborne viruses in suspension, so that, without proper treatment, it is likely to recontaminate previously decontaminated surfaces.

Following (b), the virucidal agents can be gases such as formaldehyde, chlorine dioxide or liquid gases such as hydrogen peroxide.

According to (c), only the surfaces and the volume of air exposed directly to germicidal radiation at a limited distance are treated, in other words, the porous surfaces or surfaces made of fabrics are not treated beyond their external surface because they remain hidden from germicidal radiation.

Viruses encountered during the contamination of premises are likely to be present in aerosols (suspended in the air), thus making indoor air a vector for the spread of contamination.

Following (b), different techniques are currently proposed for viral disinfection of fomites via ambient air. These methods of disinfecting fomites by air often have a limited impact on viral aerosols. Their uses and optimizations generally relate to the only decontamination of fomites.

The virucidal agents employed are either aerosolized liquids or gases.

The implementation of these techniques requires expensive equipment and highly qualified personnel.

Aerosolization of liquids is particularly tricky because its effectiveness depends on the size and homogeneity of the droplets.

For many years, various air disinfection techniques have been proposed and claim a virucidal effect. The majority consists of equipment through which air circulates in contact with filters, ozone, photocatalysts, plasma, UVC radiation. These latter techniques can be combined in the same device. Only the air circulating in said devices is assumed to be treated, faced with significant volumes of premises or fomites of large or complex surfaces, it is impossible to ensure that all the ambient air has been treated while aerosolized viruses can continue to be there, thus rendering this equipment ineffective in the face of large volumes of air to be treated and / or complex volumes or surfaces.

A persistence of virucidal activity beyond the equipment, beyond its processing volume, is also observed with the use of ozone, in the state of the art. In addition, the efficiency of this gas is strongly impacted on the one hand by its concentration in the air and on the other hand by the humidity level of the air. In other words, the relative humidity of the ambient air is involved in the biocidal capacity of ozone when this gas is introduced into said ambient air to carry out its disinfection. This influence results from the formation of specific ions which are particularly oxidizing during the decomposition of ozone. Ozone is known to attack unsaturated bonds and form aldehydes, ketones or carbonyl compounds. In addition, ozone can react very quickly with amino acids, proteins, protein functional groups and nucleic acids.

The reason for the importance of humidity in the ozone disinfection process is twofold. The first is physical. Higher humidity levels allow the rehydration of desiccated pathogens, which decreases their resistance to the action of ozone. Water also tends to form a thin layer around biological materials such as bacteria and viruses. In surface disinfection, this allows for the creation of a larger surface contact between the target pathogens and the ozone. This is significant for the second reason why humidity is a decisive factor for the biocidal effectiveness of ozone, as explained below.

From a chemical point of view, and in the presence of water, the destructive action of ozone can follow two distinct paths: either by direct action, or by reaction intermediates called radical species. Because molecular ozone is very reactive, it can also react with water and form transient radical species which have extremely short but very reactive lifetimes. Similar to ozone, these species exhibit high oxidizing power and in turn can react with and inactivate harmful pathogens such as bacteria, viruses, fungi and yeasts.

The equipment for disinfection by ozonation of indoor air available in the prior art is often proposed for treatment in human presence. According to the technical instructions for ozonation equipment intended for disinfection, the ozone levels used are at most a few tenths of ppm / m ³ in the treated air, at the outlet of the devices, mainly with regard to international and European standards which set the maximum level of ozone in the air. For example, in Europe, the limit value for the protection of human health is defined as a daily maximum of the 8-hour moving average of 120 μg / m ³ , or 0.061 ppm.

Several scientific studies have demonstrated the need to reach several tens of ppm of ozone in indoor air to achieve partial inactivation of bacterial and fungal aerosols.

Depending on the pathogens encountered, their modes of transmission via microdroplets and their ability to remain infectious when present in aerosols are poorly documented. However, the scientific community agrees that for a virus such as COVID 19, it can remain infectious for several hours in suspension in the air (aerosol) and several days on inert surfaces.

Until now, the primary mechanism by which ozone inactivates a virus has not been well understood. However, the applicant's research has led him to understand that ozone reacts with the virus by direct reaction with molecular ozone and by radical species that form during its decomposition.

According to the subject of the invention, the applicant therefore proposes a method for inactivating viruses present in a space defined by the controlled use of molecular ozone injected into the ambient air of the space defined to be treated ( i.e. the air in contact with the virus) and by regulating the relative humidity (in other words the humidity rate) of the ozonated ambient air in order to significantly increase the viral inactivation reactions for a given molecular ozone exposure dose and therefore therefore greatly reduce the exposure dose required compared to ozonation in air with lower relative humidity. Furthermore, for low to medium humidity, it seems materially impossible to achieve the theoretical exposure doses required for many pathogenic viruses.

Ozone is known to attack unsaturated bonds and form aldehydes, ketones or carbonyl compounds. In addition, ozone can react very quickly with amino acids, proteins, protein functional groups and nucleic acids. Consequently, ozone would act on the protein structure of the viral capsid or on the nucleic acids of the virus.

PRESENTATION OF THE INVENTION

More specifically, the invention relates to a viral disinfection process for a defined space, comprising:

Molecular rehydration of ambient air in defined space; and

The diffusion into the ambient air in the defined space, in particular confined space, of molecular ozone with an exposure dose CT, corresponding to the product C x T where C represents the concentration of molecular ozone and T represents the duration of treatment, greater than 2 mg.min / m ³ , preferably substantially constant and equal to 5 mg.min / m ³ .

The molecular rehydration of the ambient air in the defined space is carried out by:

The generation of negative ions in the air and bringing the ambient air to be treated into contact with the negative ions in the air generated, and / or by:

The forced humidification of the ambient air in the defined space and the regulation of the humidity level of the ozonated ambient air in the defined space.

According to one embodiment, the regulation of the humidity level of the ambient air in the defined space is configured so that said humidity level in the ambient air in the defined space is maintained above 70%, preferably substantially constant and equal to 85%, for an ambient air temperature substantially equal to 25 ° C.

According to one embodiment, the regulation of the humidity level in the ambient air in the defined space comprises humidifying said ambient air in the defined space, so as to increase the concentration of ozone decomposition products. molecular, in particular hydroxyl ions and free radicals, in the ambient air of the defined space.

According to one embodiment, the implementation of the method being carried out for a total duration:

The diffusion of molecular ozone is carried out for a first duration less than the total duration;

The humidification of the ambient air is carried out in the defined space after the expiration of the first period and for a second period ending at the latest at the same time as the total period.

According to one embodiment, the method comprises the exposure dose CT is greater than 2 mg.min / m ³ for the treatment of the ambient air in the defined space only.

According to one embodiment, the exposure dose greater than 200 mg.min / m ³ for the treatment of fomites within the defined space.

According to one embodiment, the method further comprises a final step of destroying the residual molecular ozone in the ambient air of the defined treated space.

According to one embodiment, the method comprises a preliminary step of confining the defined space to make it a confined space.

The invention also relates to a viral disinfection system of a defined space comprising an ozonator and a humidifier configured to implement the method briefly described above.

According to one embodiment, the ozonator comprises an electric arc generating device for creating a corona effect or a device for generating ultraviolet rays of the UV-C type having a wavelength between 160 nm and 220 nm.

Advantageously, the humidifier comprises an adiabatic evaporation device by vaporization or by ultrasound emission or by spraying.

In addition, it is known to the applicant that the humidification of the air as described in the invention presents significant technical and therefore financial constraints. Moreover, the presence of humidity in the air subjected to ionization leads to the formation of oxidizing compounds for metals such as nitric acid from the nitrogen in the air, hence the need noted by the applicant to humidify the air after the ozonation sequence.

According to a variant of the invention, the humidification sequence can be advantageously replaced by carrying out a negative ionization sequence of the air to be treated prior to its ozonation.

PRESENTATION OF FIGURES

The invention will be better understood on reading the following description, given by way of example, and referring to the following figures, given by way of non-limiting examples, in which identical references are given to similar objects. .

: the is a block diagram showing an embodiment of the method according to the invention;

: the is a schematic representation of an example of a disinfection chamber implementing the invention;

: the is a schematic representation of another example of a disinfection chamber implementing the invention;

: the is a schematic representation of the decomposition and recomposition of negative ions in air.

It should be noted that the figures set out the invention in detail to implement the invention, said figures can of course be used to better define the invention if necessary.

DETAILED DESCRIPTION OF THE INVENTION

The invention is presented primarily for the purpose of enabling viral disinfection of air and associated fomites in a defined space. However, other applications of the method according to the invention can be envisaged in particular, a mobile unit for viral disinfection of the air supplying devices such as respiratory masks or tight suits used by workers in a contaminated atmosphere. by viruses.

As previously indicated, the present invention relates to a method for viral disinfection of air and associated fomites in a defined space. It is therefore necessary to define the doses of ozone necessary and the level of humidity necessary to obtain the envisaged viral infection. To do this, several definitions must be made.

According to Applicant's research, the dose of ozone to which an airborne virus has been exposed is defined as the product of the ozone concentration on the virus and the contact time (TC). The survival fraction (unitless SF) is a ratio that represents the virus concentration after exposure to ozone:
[Math. 1] FS = Ns / No = e ^{- KTC}

with :

Ns is the concentration of surviving airborne viruses in ambient air in defined space after exposure to molecular ozone;

No is the initial concentration of airborne viruses in the ambient air in the defined space to be treated (before exposure to ozone);

C is the concentration of molecular ozone in ambient air in the defined space (mg / m ³ );

T is the ozone / air contact time in minutes;

K is the susceptibility of the virus to ozone (m ³ / mg.min).

The molecular ozone exposure dose, here determined as necessary, said exposure dose also being designated CT (product C x T where C is the molecular ozone concentration and T is the treatment time or, in other words, the time of contact between molecular ozone and the ambient air to be treated), is greater than 2 mg.min / m ³ of ozonated air (i.e. 1.02 ppm) and preferably substantially equal to 5 mg.min / m ³ of ozonated air (ie 2.55 ppm) for elimination of the majority of known viruses at 99% under a relative humidity greater than 70%, preferably substantially equal to 85%, and at 25 ° C. ambient temperature.

With reference to the , the method according to the invention thus comprises a step E1 of diffusion of molecular ozone into the ambient air of the space defined to be treated and, then, a step of forced humidification, that is to say of injection of water in nebulized form, for example, and regulation of the humidity level in the ozonated ambient air in the defined space.

For example, the total treatment time can be between 6 minutes and 8 minutes, including a first duration between 1 minute and 2 minutes of injection of concentrated molecular ozone, and a second duration, of humidification of the air. ozonated ambient, for a period of between 5 minutes and 6 minutes.

Preferably, a step E3 is then provided for destroying the residual molecular ozone in the ambient air of the defined treated space.

According to the applicant's research, due to the complexity of the surfaces, materials and surface deposits encountered, the fomite (s), which are treated by fallout, must be treated at a dose of exposure ozone or CT much more important than for viral aerosols present in the ambient air of the defined space, in particular of the order of 100 times greater than the exposure dose required for the treatment of ambient air only, subject to 'a rapid rise in the relative humidity of the ozonated air. For the treatment of the ambient air of the defined space and the fomites it contains, we recommend:

Step E1: molecular ozone is diffused in the defined space so as to achieve an exposure of the ambient air in the defined space to molecular ozone with a CT value (or exposure dose) for treatment fomites greater than 200 mg.min / m ³ of ozonated air (ie approximately 102 ppm) and preferably substantially also ^{greater than 500 mg.min / m 3} of ozonated air (ie approximately 255 ppm);

Step E2: in particular immediately following the exposure time determined by the criterion relating to the maintenance of the exposure dose (or TC) determined above, humidification of the ambient air in the space defined for obtain a rapid rise in the relative humidity of the ozonated air; in particular, the humidity level in the ambient ozonated air in the defined space is made and maintained greater than 70%, preferably substantially equal to 90%, by means of a humidifier, for a time greater than 1 minute and preferably substantially equal to 5 minutes, or even substantially equal to 6 minutes.

The majority of viruses known to be greater than 99% are eliminated in this way at 25 ° C room temperature.

It therefore appears from the applicant's research that the exposure dose required by molecular ozone for the treatment of fomites is 100 times greater than the exposure dose required to inactivate airborne viruses. This results from the complexity of the surfaces (grooves, crevices, porosities, etc.), of the materials constituting the supports and of the virus support matrix.

If the defined space is not initially confined, it is preferable to carry out, before implementing step E1 of the process, a step of confining the defined space in order to make this space confined.

Such a confined space is defined as a closed space, totally or partially, with the following characteristics: i) the means of access, both outside and inside, are restricted; in particular, a confined space is here made substantially hermetic to outside air; ii) optionally, this space is not previously designed or intended to be occupied by staff working inside; iii) sometimes, when entering these spaces, operators can be exposed to a significant number of risks that should be controlled.

Referring to Figures 2 and 3, there is shown two variant embodiments of a system capable of implementing the method described above, in which the ambient air to be treated is exposed to molecular ozone in a chamber of ozonation 100, then the ozonated ambient air is humidified so as to guarantee a sufficient humidity level in a humidification chamber 200.

In the example of , the generation of molecular ozone in the ozonation chamber 100 is carried out by an ozonator 10, also referred to as an ozone generator, in particular mobile, composed mainly of UV-C lamp (s) emitting light having a length of wave of about 185 nm. UV-C lamps generating molecular ozone emit UV-C type ultraviolet rays having a wavelength between 160 nanometers and 220 nanometers, generally substantially equal to 185 nanometers.

Ozone is created when the oxygen molecules O ₂ are separated by radiation, the oxygen molecules split in two and then reform into O ₃ molecules, that is to say molecular ozone.

The so-called UV-C lamp (s) are placed in a flow of ambient air to be treated, in particular generated by a fan (not shown).

In the example of , the generation of molecular ozone in the ozonation chamber 100 is carried out by another type of ozonator 11, namely an ozone generator by the corona effect. Such an ozonator 11 - generator of ozone by the corona effect - generates an electric arc which generates the re-composition of oxygen O2 into ozone O3. As in the other example, the ozonator 11 by the corona effect is placed in an ozonation chamber 100, the volume of which is filled with air sucked into the defined space to be treated, said air being ozonated in said chamber d. ozonation 100 before being released into the ambient air of the defined space. It is noted that the preferred embodiment, for the generation of molecular ozone, however, lies in the use of UV-C lamp (s) because the corona ozone generators have the disadvantage of requiring very dry air. to function optimally. Without dry air, ozone generators by corona effect have indeed a production of ozone which is reduced over time and their lifespan becomes very short because the metallic elements that create the electric field are easily oxidized in air. humid environment.

A UV-C lamp, on the other hand, does not need dry air and does not oxidize, which makes it a device more suited to a context of use in a preferentially humid ambient air, as explained previously.

The ambient air to be treated A is preferably drawn into the defined space to be treated by means of the fan opening into an ozonation chamber where the UV-C lamp (s) is (are) placed, after having in particular passed through a filter 2A, 2B which may be a washable dust filter. A non-return valve 41 can be provided to prevent backflow of the air entering the ozonation chamber 100.

After sufficient contact time between the molecular ozone diffused by the ozonator 10, 11 and the ambient air to be treated in the ozonation chamber 100, the ozonated ambient air is directed out of the ozonation chamber into the defined space to be treated.

According to one embodiment, the operation of the ozonator 10, 11 is controlled and controlled by means of a probe for measuring the molecular ozone level arranged in the defined space to be treated. Said probe has, for example, a means of cutting off the power supply to the ozonator 10 when the expected molecular ozone level (that is to say when the ozone concentration in the ambient air of the space defined to be treated ensures, given the treatment time, an exposure dose (or CT) greater than the predefined threshold) in said defined space is reached.

At the end of the ozonation step E1, comes the forced humidification and humidity control step, in other words the humidification of the ozonated ambient air. Air humidification consists in particular of injecting water in the form of a humid mist, in other words in the form of microdroplets, so that it is absorbed by the ambient ozonated air, so as to increase the rate of humidity of said ozonated ambient air. The finer the microdroplets, the better the absorption. Air humidification techniques are mainly by evaporation (adiabatic), vaporization, ultrasound or spraying.

According to an embodiment not shown, the humidification of the ozonated ambient air is carried out in the space defined by a humidifier consisting of a mobile electric air mist.

According to one embodiment, the start-up of the humidifier is preferably carried out automatically, when the ozonator is stopped, in other words at the end of step E1 of ozonation of the ambient air of the ozonator. defined space.

According to one embodiment, the operating time of the humidifier, in particular of the aeromist, is controlled by means of a relative humidity probe placed in the defined space to be treated.

With reference to FIGS. 2 and 3, the humidification of the ozonated ambient air is carried out in a humidification chamber 200 disposed at the outlet of the ozonation chamber 100. For example, with reference to , a humidifier 20 is provided at the inlet of the humidification chamber 200 which adjoins the ozonation chamber 100. The humidifier 20 is then for example an adiabatic humidification cassette containing foam or felt humidified via a reserve of 'water 3.

In the example of , humid air H, which may for example come from a recirculation of the user's exhaled air is injected into the humidification chamber 200 via a pipe provided with a non-return valve 43.

According to one embodiment, upon stopping the treatment phase under controlled humidity, corresponding to the step, during which a humidity level in the ambient air to be treated greater than the predefined threshold is ensured, a destroyer of ozone 30, in particular by catalysis, is put into operation in the defined treated space. In particular, the shutdown of the ozone destroyer 30 is controlled by the ozone level monitoring probe when the latter detects a molecular ozone concentration in the treated ambient air of less than 1 ppm.

In Figures 2 and 3, the ozone destroyer 30 is shown schematically in the form of a catalyst filter. Those skilled in the art have at their disposal a whole panel of catalysts known to perform this function. Reference may in particular be made to the thesis "Synthesis and characterization of new heterogeneous catalysts for air pollution control", presented and defended by Benjamin FAURE, on December 9, 2014, at the University of Toulouse 3 Paul Sabatier.

Advantageously, according to a preferred embodiment, the ozonation (ozonator 10, 11), humidification (humidifier 20) and ozone destruction (ozone destroyer 30) devices are controlled by means of a control module. control 50 connected to a probe for measuring the level of ozone in the ambient air of the space defined to be treated and to a relative humidity probe, configured to measure the level of humidity of the ambient air, in particular ozonated , in the defined space, said probes being arranged in the defined space to be treated so that the viral disinfection method according to the invention can be implemented without human presence, in particular in the defined space to be treated . At the outlet of the system, a non-return valve 42 can be provided and the outgoing air S is reinjected into the ambient air of the defined space.

The system includes for this purpose a probe to measure the ozone concentration in the ambient air. The ambient air of the defined space is considered to be breathable when, after carrying out the viral disinfection process, the concentration of molecular ozone in the ambient air is reduced to a level below 1 ppm.

In the event that no ozone destroyer intended to reduce the level of residual molecular ozone in the ambient air of the defined treated space is provided, it is recalled that molecular ozone degrades naturally, its half-life being reduced. As a reminder, the half-life of molecular ozone is thus of the order of a few days at temperatures between -25 ° C and + 20 ° C (approximately 3 days at 20 ° C), said half-life being reducing with increasing temperature. Humidity also reduces the half-life of ozone.

As a result, the concentration of molecular ozone in the ambient air of the defined space will naturally fall below the above threshold after a few hours

Other devices (not shown and briefly described below) are provided to allow viral disinfection of air and associated fomites in specific defined spaces.

In summary, the present invention relates to a method for viral disinfection of air and associated fomites in a defined space. More precisely, the present invention relates to a method for viral disinfection of the ambient air and of the associated fomites in a defined space comprising an ozonation step immediately followed by a step of rapid humidification of the ozonated ambient air in order to to increase the formation of hydroxyl ions and radical species during the decomposition of molecular ozone in contact with water vapor and thus on the one hand to optimize the destruction of viruses contained in the ambient air to be treated and on the other hand also to reach certain encapsulated viruses or viruses integrated into organic matrices while significantly reducing the dose of exposure required to molecular ozone compared to lower humidities. This reduction in the necessary exposure dose (or CT) thus makes it possible to make molecular ozonation compatible with the use constraints and / or technically limiting.

The present invention therefore allows direct action of the ozone O ₃ molecule followed by the action of hydroxyl ions and free radicals, decomposition products of molecular ozone, on airborne viruses and fomites.

Indeed, molecular ozone acts primarily on the capsids (a kind of protective protein shell) of airborne viruses in the ambient air of the defined space to be treated, but it also acts on the nucleic acids of these viruses. Hydroxyl ions and free radicals, resulting from the decomposition of the ozone molecule and therefore the presence is reinforced in the presence of humidity, act on the content of the virus capsid, namely at least one nucleic acid generally stabilized by basic nucleoproteins. The ambient air to be treated is thus treated by the association between the diffusion of molecular ozone, with maintaining an exposure dose above a predefined threshold, and the regulation of a sufficient humidity level.

It is further specified that the present invention is not limited to the examples described above and is susceptible of numerous variations accessible to those skilled in the art.

ApplicationApplication s envisagéess envisaged : :

Several uses of the invention are envisaged, without the list given below being able to be interpreted restrictively.

First, for the viral disinfection of premises or cars (private vehicle, bus, train, plane, etc.), it is planned to carry out the initial stage of confinement of the defined space to be treated, so as to make it hermetic and thus allow a greater efficiency of the treatment. Then, the system as defined above, previously installed in said space, is put into operation. It is noted that the ozonator and the humidifier may be two separate machines or be two devices encapsulated in the same machine.

It is also planned to implement the invention to disinfect a disinfection airlock and access to an infected confined space. In this case, people intended to enter this confined infected space are equipped with a breathing mask when they are in the disinfection chamber.

It is also intended that the invention be used for making individual and portable stand-alone units. Such autonomous units are, for example, integrated into a protective suit for people operating in an infected environment. In such a stand-alone unit, molecular ozone is produced in the ozonation chamber, by corona effect or UV-C lamp, depending on the incoming air flow. The ozone production is adjusted according to the incoming air flow with a concentration suitable for a treatment time of 10 to 20 seconds, for example, in order to ensure the required exposure dose. The ozonated air is humidified by any humidifier, in particular capable of exploiting the humidity present in the air exhaled by the person equipped with the diving suit, then the treated air passes through a catalyst filter to destroy the residual molecular ozone so as to constitute an air flow intended to ventilate said person.

It is also planned to implement the invention to disinfect aeraulic or climatic ducts supplying premises with disinfected air.

Variante de réalisation : ions coronaVariant of realization: corona ions

The air ions hereinafter referred to as NAI (abbreviation of Negative Air Ion (s) in English), have molecules or atoms electrically charged in the atmosphere. An air ion is formed when a gaseous molecule or atom receives energy high enough to eject an electron. Negative air ions NAI are those that gain an electron, while positive air ions lose an electron.

Artificial corona discharge is an effective way to generate NAI. When a high negative voltage is applied to a conductor or electrode and the generated electric field is high enough, corona discharge occurs. If a charged conductor / electrode has a type of needle with a sharp tip, the electric field around the tip will be significantly higher than other parts and the air near the electrode can become ionized and NAIs are generated. The intensity of the corona discharge depends on the shape and size of the conductors as well as the applied voltage. An irregular conductor, especially with a sharp tip, results in more crown than a smooth conductor, and large diameter conductors produce a smaller crown than small diameter conductors. The higher the applied voltage, the more NAIs are generated. The closer the distance to the corona point, the higher the concentration of NAI, because the continuous generation of NAI by corona discharge is related to a chain reaction process called an electron avalanche. A corona discharge produces air ions and ozone. Ozone production can be limited and lowered below the detection threshold by adjusting the discharge parameters.

In general, the NAIs generated are not stable and will be gradually degraded. In the presence of humidity (even low) and water droplets even condensed after partial evaporation, the NAIs released into the ambient air easily combine with water molecules and thus form negative ion clusters of larger sizes. important and longer life. NAIs are composed of several negatively charged molecules and these negative ions combine with several or up to 20 or 30 water molecules and form clusters of negative ions such as CO ₃ - (H ₂ O) _n , O - (H ₂ O) _n and O ₃ - (H ₂ O) _n . The viral loads composing the aerosols, in particular in the form of droplets initially condensed by evaporation, are then held in these clusters.

With reference to the , NAIs can evolve from one NAI to another NAI. For example, the NAI O- is formed when an oxygen molecule O2 obtains an electron. NAI O- may contribute to the formation of secondary NAIs by collision-assisted electron attachment processes when other molecules exist in the same space. As a result, other NAIs are generated such as O2 -, CO4 -, CO3 -, OH -, HCO3 -, O3 -, NO3 - and NO2 -, the evolution of the NAI is linked to the composition of the ambient air . NAIs continually change when they collide with molecules in the air. Thus, NAIs are dynamic in their composition, which depends on the ionization potential and electron affinity, proton affinity, dipole moment and polarizability as well as the reactivity of the molecule.

It is useful to specify that, within the meaning of the invention, the injection of NAI into the ambient air prior to its ozonation has two advantages:

- They promote the formation of molecular clusters of water that trap viral loads;

- They are partly composed of oxidizing ions and free radicals.

According to the subject of this variant of the invention, the aggregation and hydration of the aerosolized viral particles in the (H ₂ O) _n clusters formed by the action of the NAI favorably replace or complete a forced humidification of the ambient air as presented in the first embodiment of the invention, in step E2, described above.

In other words, to rehydrate the viral particles in the ambient air, the variant embodiment provides that the NAI ions injected into the air cause the formation of aggregates of water molecules and therefore the molecular hydration of the aerosolized viral loads, in particular by the rehydration of the viral droplets condensed by partial evaporation.

Thus, the method according to the invention causes in particular the oxidation of viral loads by supplying ions and oxidizing radicals within molecular clusters of _{aerosolized H 2} O, the formation of which it causes.

This variant embodiment replaces or supplements the first embodiment described, according to which a forced humidification of the ambient air to be treated is carried out, in the defined volume, for example by means of injection of water, in particular nebulized, which generates rehydration of the ambient air corresponding to a diffusion of clusters of water molecules.

In addition, the presence of oxidizing ions and oxidizing radicals participate upstream and then in the presence of ozone in the inactivation of viral loads. As such, it is specified that the ionization step (generation and injection of negative air ions) and of mixing these ions with the ambient air can be used in human presence and that it can therefore be maintained as a preventive measure between two phases of ozonation treatment (with or without humidification) which could only be implemented here in the event of suspected contamination (curative treatment).

According to this variant of the invention, the ambient air to be treated is brought by mechanical means into contact with the NAI-generating corona device, the air charged with NAI is then diffused by any means into the ambient air.

According to experiments carried out by the inventor, the speed of passage of the air to be treated in contact with the NAI generator should preferably be less than 1 m / s and more preferably be of the order of 0.5 m / s

For greater efficiency, the production of NAI in the air treated to obtain the expected effects must be greater than 100,000 ions / cm ³ and preferably of the order of 450,000 ions / cm ³ of air flow passing in contact with the generator. The concentration of NAI carried in the ambient air must be greater than 1000 ions / cm ³ and preferably of the order of 5000 ions / cm ³ .

As a variant, fibers, woven materials or plastic profiles, preferably PTFE, are placed in the air flow upstream of the NAI generator in order to positively charge by triboelectric effect the water molecules present in the air to be treated. . This arrangement promotes the speed of attraction between the latter and the NAIs.

Claims

Viral disinfection process for a defined space, comprising:

molecular rehydration (E2) of ambient air in the defined space; and

the diffusion (E1) in the ambient air in the confined space of molecular ozone with an exposure dose CT, corresponding to the product C x T where C represents the concentration of molecular ozone and T represents the duration of treatment, greater at 2 mg.min / m 3 , preferably substantially constant and equal to 5 mg.min / m 3 .
The method of claim 1, wherein the molecular rehydration of the ambient air in the defined space comprises generating negative ions from the air and contacting the ambient air to be treated with the negative ions from the air. air generated.
A method according to claim 1 or 2, wherein the molecular rehydration of the ambient air in the defined space comprises forced humidification of the ambient air in the defined space and the regulation of the humidity level of the air. ozonated ambient in the defined space.
A method according to claim 3, wherein the control of the humidity level of the ambient air in the defined space is configured such that said humidity level in the ambient air in the defined space is maintained above 70 %, preferably substantially constant and equal to 85%, for an ambient air temperature substantially equal to 25 ° C.
A method according to one of claims 3 to 4, wherein the regulation of the humidity level in the ambient air in the defined space comprises humidifying said ambient air in the defined space, so as to increase the concentration of decomposition products of molecular ozone, including hydroxyl ions and free radicals, in the ambient air of the defined space.
Method according to Claim 5, in which, the implementation of the method being carried out for a total period of time:

the diffusion (E1) of molecular ozone is carried out for a first duration less than the total duration;

the forced humidification of the ambient air is carried out in the defined space after the first period has elapsed and for a second period ending at the same time as the total duration at the latest.
Process according to one of Claims 1 to 6, in which the exposure dose is greater than 2 mg.min / m 3 for the treatment of ambient air in the defined space only.
Process according to one of Claims 1 to 6, in which the exposure dose is greater than 200 mg.min / m 3 for the treatment of fomites within the defined space.
Method according to one of claims 1 to 8, further comprising a final step (E3) of destroying the residual molecular ozone in the ambient air of the defined treated space.
Method according to one of claims 1 to 9, comprising a preliminary step of confining the defined space to make it a confined space.
A defined space viral disinfection system comprising an ozonator (10, 11) and a humidifier (20) configured to carry out the method according to claim 3 and one of claims 4 to 9.
A system according to claim 11, wherein the ozonator (10, 11) comprises an electric arc generating device for creating a corona effect or a device for generating ultraviolet rays of UV-C type having a wavelength comprised between 160 nm and 220 nm.
A system according to claim 11 or 12, wherein the humidifier (20) comprises an adiabatic vaporization or ultrasonic emission or spray evaporation device.