METHOD AND DEVICE FOR DISINFECTING AIR SUCTED IN BY A PERSON

Description

[0001] The present invention relates to an air disinfection device associated with an oro-nasal respiratory mask for protection against infections, and a method for disinfecting the air breathed by a person.

[0002] Ultraviolet (UV) light, particularly in the UV-C wavelength range (240 to 280 nm), acts against viruses and bacteria by killing them or rendering them incapable of infecting a person. This is why UV lamps are found in many air and water purification devices, or in disinfecting cabinets for objects such as glasses or telephones.

[0003] It has also been proposed to integrate one or more UV lamps into an oro-nasal respiratory mask for protection against infections, to eradicate viruses and bacteria. It turns out that the light intensity of the emitted UV radiation and the time of exposure to UV are insufficient to have a real effect on the air breathed through a respiratory mask. In reality, the emitted ultraviolet rays only have an effect on the germs present on the surface of the mask.

[0004] Examples are disclosed in CN111194955 A, WO03092748 A1 and CN111053979 A.

[0005] The doses of ultraviolet needed to eradicate viruses and bacteria in a volume of air depend on several factors, namely the wavelength and light intensity of the UV radiation received, as well as the exposure time, and more precisely, the dose received which is equal to the product of the light intensity of the UV radiation by the exposure time. Furthermore, it is generally accepted that the survival of germs to ultraviolet exposure follows an exponential decay model, of the form S = e -kD< , where S represents the fraction of germs still present after exposure to ultraviolet, D represents the dose applied, and k a coefficient which is specific to each germ.

[0006] Furthermore, breathing rates vary significantly depending on whether the person is at rest or engaged in physical activity, and from one person to another.

[0007] It is therefore desirable to provide a device that is effective in disinfecting a highly variable volume of air inhaled or exhaled by a person. It is also desirable that this device can be easily worn by a person, without hindering their daily movements.

[0008] Embodiments relate to a method for disinfecting the air breathed by a user, the method comprising steps consisting of: subjecting the interior of a first chamber in communication with an external volume of air to a first source of ultraviolet radiation having a wavelength capable of destroying germs, subjecting the interior of a second chamber in communication with the external volume of air to a second source of ultraviolet radiation, detecting the instants of start of respiratory phases of inspiration and expiration of air carried out by the user, each respiratory phase being associated with a forward or reverse direction of air circulation in a conduit during the respiratory phase, during a first respiratory phase in a forward direction following a first respiratory phase in a reverse direction,circulating the air from the first chamber between an interior volume of a breathing mask sealingly covering the user's mouth and nose and the exterior air volume, the first forward respiratory phase being followed by a second reverse respiratory phase, and during a second forward respiratory phase following the second reverse respiratory phase, circulating the air from the second chamber between the interior volume of the breathing mask and the exterior air volume.,

[0009] According to one embodiment, the method comprises a step of detecting that the air in the first chamber is completely renewed before the end of the first forward respiratory phase, followed by a step of circulating the air in the second chamber alternately with circulating the air in the first chamber, between the interior volume of the respiratory mask and the exterior air volume.

[0010] According to one embodiment, the method comprises several alternating steps of circulating the air from the first chamber and circulating the air from the second chamber, between the interior volume of the respiratory mask and the exterior air volume, during the first forward respiratory phase, each alternation being triggered by the detection that the air is completely renewed in the first or second chamber.

[0011] According to one embodiment, the method comprises steps of extinguishing the first and second sources of ultraviolet radiation during each reverse direction respiratory phase.

[0012] According to one embodiment, the first and second respiratory phases in the forward direction are inspiration phases of the user, and the first and second respiratory phases in the reverse direction are expiration phases of the user, or the first and second respiratory phases in the forward direction are expiration phases of the user, and the first and second respiratory phases in the reverse direction are inspiration phases of the user.

[0013] According to one embodiment, the method comprises steps of activating a fan to circulate air during each forward respiratory phase.

[0014] Embodiments may also relate to a device for disinfecting air breathed by a user, the device comprising: a first chamber and a second chamber, in communication with an external volume of air and coupled by a controlled valve device, to a first conduit connected to the internal volume of a respiratory mask, a source of ultraviolet radiation, installed inside each of the first and second chambers, and a measuring device for determining a direction of circulation of the air in the first conduit, the disinfection device being configured to implement the method defined previously, the detection of the instants of start of respiratory phases of inspiration and expiration of air being carried out using the measuring device, and the circulation of the air in the first chamber and in the second chamber being carried out using the valve device.

[0015] According to one embodiment, each of the first and second chambers includes a ventilation device for circulating air through the chamber.

[0016] According to one embodiment, the ventilation device comprises a pump or a fan and / or implements the Coanda effect.

[0017] According to one embodiment, the UV radiation source in each of the first and second chambers comprises a UV quartz tube lamp or UV LEDs.

[0018] According to one embodiment, the device is installed in a portable housing, including a self-contained electrical power source.

[0019] According to one embodiment, each of the first and second chambers is associated with a compressor to increase the pressure in the chamber.

[0020] According to one embodiment, the UV radiation source is installed in each of the first and second chambers and configured to subject an exposure volume in the chamber to a light intensity greater than or equal to 10 mW / cm 2< .

[0021] Examples of embodiments of the invention will be described in the following, without limitation, in relation to the attached figures, among which: [ Fig. 1 ] there figure 1 schematically represents a disinfection device, according to one embodiment, [ Fig. 2 ] there figure 2 schematically represents an element of the disinfection device, according to one embodiment, [ Fig. 3 ] [ Fig. 4] [Fig. 5 ] THE figures 3 à 5 are schematic timing diagrams of variation in the flow rate of breathed air, illustrating the operation of the disinfection device, according to various embodiments.

[0022] There figure 1 represents a device 10 for disinfecting breathing air, according to one embodiment. The device 10 comprises two chambers T1, T2, an electrically controlled EV valve device, a pressure sensor PS, two non-return valves C1, C2, and a PRC processor receiving pressure measurement signals from the pressure sensor PS and controlling the EV valve device and the chambers T1, T2. The device 10 also comprises a sealed oronasal respiratory mask 2, arranged to be fixed on the head of the user 1 so as to cover the user's mouth and nose in a sealed manner. The interior volume of the mask 2 is connected to the valves C1, C2 by two pipes 3, 4. The valve C2 is connected to an inlet 7 of the device by a pipe 5, the inlet 7 being open to the ambient air. The valve C2 can be integrated directly into the mask 2.The valve C1 is connected to the valve device EV by a line 6, the EV device being connected to the chambers T1, T2 by lines 8, 9, respectively. The pressure sensor PS measures the pressure in the line 4, for example in the valve C1. The valve device EV is arranged to connect the line 6 either to the line 8 to the chamber T1, or to the line 9 to the chamber T2. Each chamber T1, T2 comprises an inlet I1, I2 open to the ambient air, and a source of UV radiation (. figure 2 ). Each chamber T1, T2 may also include a fan to facilitate air circulation in the device and avoid imposing additional effort on the user 1 to breathe. The device 10 also includes one or more BT batteries to power the PRC processor, the PS sensor, the EV device and the chambers T1, T2 (in particular the radiation source).

[0023] The assembly of the chambers T1, T2, the BT battery, the EV valve device and the PRC processor may be arranged in a housing (box or bag) associated with fastening means for suspending the housing from the neck or shoulders of the user 1, or for holding it around the user's waist. The BT battery may be arranged in a separate case, for example fixed to the user's waist.

[0024] When user 1 exhales air, valve C2 opens, while valve C1 remains closed. The exhaled air is therefore expelled through opening 7. When the user inhales air, valve C1 opens, while valve C2 remains closed. The PRC processor controls the EV device so as to connect line 6 with chamber T1 and chamber T2, alternately. Thus, the inspired air comes either from chamber T1 or from chamber T2, which fills up gradually, via its inlet I1, I2.

[0025] The direction of air circulation in lines 6, 8 and 9, and in chambers T1, T2 can be reversed, for example to disinfect the air exhaled by user 1, by reversing the connections of lines 5, 6 to valves C1, C2.

[0026] The pressure sensor PS may be a piezoresistive sensor integrated in a semiconductor component having a gas inlet and outlet, and providing an analog voltage proportional to the gas flow rate between the inlet and the outlet. The sensor PS may be connected in bypass with the valve C1. The pressure sensor PS may also comprise a paddle wheel or a propeller arranged in the pipe 4 or 6 and associated with a device for measuring the speed of the wheel or propeller. The measurement of this speed makes it possible to determine the speed of the air flow in the pipe and therefore the air flow rate.

[0027] The EV valve device may be of the three-way, two-position solenoid valve type. Thus, the solenoid valve may comprise an electromagnet which, at rest, keeps the connection open to chamber T1 (connection between lines 6 and 8 open and connection between lines 6 and 9 closed), and under voltage, keeps the connection open to chamber T2 (connection between lines 6 and 9 open and connection between lines 6 and 8 closed). The EV valve device may comprise two two-way solenoid valves arranged respectively between lines 6 and 8 and between lines 6 and 9. These two solenoid valves may be mounted so as to open the connection between the two lines 6, 8 or 6, 9 when they are energized, and close the connection otherwise.

[0028] Check valves C1, C2 can have a movable valve or be of the Tesla valve type allowing a fluid to flow in one direction only without moving parts.

[0029] The PRC processor can be of the microprocessor or microcontroller type.

[0030] The mask 2 comprises an airtight shell sealingly covering the user's nose, mouth and chin. The shell may be rigid, transparent and thin, for example less than or equal to 2 mm. The shell may be made from a sheet of rhodoid. The seal between the shell and the user's face 1 may be obtained by a flexible elastomer seal. To ensure a good seal, the shape of the shell may be adapted to the shape of the user's face. The shell may be held on the user's face by elastic bands passing behind the ears or behind the head, or by glasses arms.

[0031] The pipes 3, 4 can open into the shell or be coupled to a single flexible pipe opening into the shell, and for example fixed to one of the arms of the glasses. The pipes 3, 4 or the single pipe can open into the mask through an opening made at the cheeks by a double skin leaving a passage several millimeters wide.

[0032] The adaptation of the shape of the shell to the shape of the user's face can be carried out using a 3D model of the face. The 3D model can be used to select a mask from a set of prefabricated masks, a final adaptation of the prefabricated mask can be carried out for example by thermoforming. Alternatively, the mask can be manufactured from a mold made for example using plaster strips placed on the face.

[0033] The mask can be equipped with a microphone connected to an amplifier coupled to a loudspeaker, to compensate for the fact that the mask can muffle the voice. When the user speaks, their breathing rate may be disrupted. To account for this, the PRC processor can be connected to the microphone.

[0034] There figure 2 represents a chamber T, according to one embodiment, the chambers T1, T2 possibly being identical to the chamber T. The chamber T has an elongated shape and comprising, at one end, an opening II open to the ambient air, which can be equipped with a filter F1, at an opposite end a transition zone CD1 between the chamber T and the pipe 8 or 9, and between these two ends, a zone for exposing the air present in the chamber to ultraviolet rays, the exposure zone comprising a source LL of UV radiation. The shape of the chamber T is adapted to the shape of the source LL so as to ensure substantially uniform illumination of the volume of the exposure zone. The internal walls of the chamber can be covered with a reflective coating.The CD2 transition zone may include a VT ventilator facilitating inspiration by user 1, the speed of the ventilator being controlled by the PRC processor according to the pressure measured by the PS pressure sensor.

[0035] According to one embodiment, the fan VT is arranged in or at the end of a duct CD2 fixed coaxially in the transition zone CD1, the interior of the duct CD1 being partially closed by an ellipsoid-shaped part R1 fixed coaxially in the duct CD1. The air leaving the exposure zone of the chamber T is sucked by the fan VT into the duct CD2 and the air passing through the transition zone CD1 around the duct CD2 produces a multiplier effect by Coanda effect, which makes it possible to obtain a significant air flow at the outlet of the chamber in the duct 8, 9, even with a low-power fan.

[0036] In the example of the figure 2 , the LL source has a cylindrical shape. Thus, the LL source can for example be of the low pressure quartz tube type producing radiation centered on 254 nm (exactly 253.7 nm), these wavelengths having a germinicidal action. In addition, the quartz of the tube has the advantage of filtering the wavelength of 185 nm which reacts with the oxygen in the air to produce ozone which is toxic. The exposure zone of the chamber T can also have a cylindrical shape, the LL source being fixed coaxially to the exposure zone in the chamber T. The opening II, as well as the filter F1 can then have an annular shape around the LL source, as shown in the figure 2 .

[0037] The T chamber may have any other shape, including a shape suitable for transport, for example a parallelepiped shape. In addition, the T chamber may have several openings. Furthermore, baffles may be provided around opening II to prevent UV radiation from escaping from the T chamber, knowing that UV-C is dangerous for the eyes and skin.

[0038] The LL source can also be based on light-emitting diodes (LEDs), the number and arrangement of LEDs in the exposure area and the shape of the latter being adapted accordingly to obtain a substantially uniform illumination of the volume of the exposure area. UV LEDs can produce radiation centered on 265 nm. Since UV LEDs tend to give off a lot of heat, they can be coupled with a heat pipe or a Peltier module, or even be associated with a fan.

[0039] The VT fan can be replaced by or associated with a single pump for the two chambers T1, T2, for example placed in line 6. Inlet II of each of the two chambers T1, T2 can be equipped with a non-return valve.

[0040] THE figures 3 à 5 are time-lapse diagrams of the variation of the flow rate of air breathed in the air disinfection device 10. The figure 3 illustrates more particularly the case where the volume of air present in each of the chambers is sufficient to supply an inspiration. The figure 3 shows INS inspiration phases delimited by the instants t1-t2, t3-t4, t5-t6 and t7-t8 alternating with EXP expiration phases of the user, delimited by the instants t2-t3, t4-t5, t6-t7.

[0041] Before time t1, the EV valve C1 is closed. The two chambers T1, T2 are therefore not in communication with the mask 2, the air in the chambers being subjected to UV radiation. At time t1, the user begins to inhale air, which triggers the opening of the valve C1. The PRC processor then detects a depression (pressure measurement lower than a first threshold value) and therefore commands the EV valve device to connect the lines 6 and 8 (chamber T1), and triggers the VT fan to suck the air into the chamber T1 at a speed adjusted according to the pressure measurements provided by the PS sensor.

[0042] Between times t2 and t3 (as well as at each expiration phase EXP), the user exhales air, which closes valve C1 and opens valve C2. The pressure in line 4 rises above a second threshold value. The PRC processor then commands the stopping of the ventilator VT in chamber T1.

[0043] At time t3, the PRC processor again detects that the user is inhaling air using the PS sensor, and controls the EV valve device to connect lines 6 and 9 (chamber T2). The PRC processor also starts the VT ventilator according to the pressure measured by the PS sensor. Thus, the INS inspiration phases are carried out alternately through the chambers T1, T2. As a result, during the period between times t2 and t5, extending over two EXP expiration phases and one INS inspiration phase, the air in the chamber T1 is not renewed and therefore remains exposed to UV. Similarly, during the period between times t4 and t7, extending over two EXP expiration phases and one INS inspiration phase, the air in the chamber T2 is not renewed and remains exposed to UV.

[0044] According to an exemplary embodiment, the UV radiation source LL is a low-pressure quartz tube having a length of 12.5 cm and a diameter of 3 cm, and emitting a light power of 3 W. The light intensity at the surface of the tube can be estimated at 8.4 mW / cm 2< . If the chamber T1, T2 has a volume of 0.5 l calculated by excluding the volume of the tube, and the tube being positioned in the center of the chamber, the light intensity of the UV radiation applied to the volume of air in the chamber T1, T2 is of the order of 10 mW / cm 2< .

[0045] The effectiveness of ultraviolet light against a germ is generally measured by the dose D 90 required to eradicate 90% of the germ. This value depends on the nature of the germ and the environment in which the germ is present. Various studies show that viruses and bacteria are very sensitive to UV, especially viruses in dry air and slightly less so in humid air. According to various authors, coronaviruses require doses ranging from 7 to 2410 J / m 2 < to achieve 90% reduction. Studies on the SARS-CoV-2 virus (Bianco et al., "UV-C irradiation is highly effective in inactivating SARS-CoV-2 replication", 2020, doi: https: / / doi.org / 10.1101 / 2020.06.05.20123463) establish that the average value of the D 90 dose is 2.7 mJ / cm 2< , and suggest that a dose equal to 4.7 mJ / cm 2< would be effective against all coronaviruses.

[0046] A person at rest inhales and exhales an average of 0.5 l and performs 12 to 16 respiratory cycles per minute. This results in a respiratory flow rate of 8 l / min and a minimum respiratory cycle duration of 3.8 s. An inspiration or expiration (between times ti and ti+1, with i = 1, 2, 3, ...) therefore lasts 1.9 s. Chambers T1 and T2 can therefore have a volume at least equal to 0.5 l. The air in each chamber T1, T2 therefore remains exposed to UV for 3 times 1.9 s, or 5.7 s, omitting any time intervals between the respiratory phases of inspiration and expiration.

[0047] A light intensity of 10 mW / cm 2< makes it possible to achieve a dose of 57 mJ / cm 2< during an exposure phase (between times t2 and t5 or between times t4 and t7) of 5.7 s, which is a value well above the dose of 4.7 mJ / cm 2< effective in eliminating 90% of coronaviruses. Since the law of variation of the number of germs as a function of time is logarithmic, doubling the exposure time makes it possible to destroy ten times more germs.

[0048] There figure 4 illustrates the operation of the air disinfection device 10 when the physical activity of the user 1 is more sustained, that is to say, when the volume of air inspired at each inspiration INS exceeds the volume of air in each of the chambers T1, T2. In the example of the figure 4 , the volume of each chamber T1, T2 is 0.5 l, the user's respiratory flow rate is 12 l / min, reached in 17 breathing cycles per minute. The volume of air per inspiration is therefore 0.7 l and the duration of inspiration INS or expiration EXP is 1.76 s. Each phase of inspiration INS and expiration EXP extends between times ti and ti+1, i = 11, 12, 13, 14, 15).

[0049] Before time t11, the air present in chambers T1, T2 is disinfected, and valve C1 is in its closed position. At time t11, valve device EV is controlled to put chamber T1 in communication with line 6. Between times t11 and t11', the air present in chamber T1 is completely sucked in. At time t11', processor PRC determines that all the disinfected air in chamber T1 has been sucked in based on the pressure measurement provided by sensor PS (which makes it possible to calculate the flow rate and therefore the sucked volume), and controls valve device EV to put chamber T2 in communication with line 6. Between times t11' and t12, the inspiration phase continues, with part of the disinfected air present in chamber T2 being inspired by the user. Part of the air present in chamber T2 has therefore been renewed between times t11' and t12. The user enters the expiration phase EXP between times t12 and t13.At the next inspiration phase INS, between times t13 and t14, the processor PRC controls the valve device EV to provide user 1 with all of the disinfected air present in chamber T2, then a portion of the disinfected air present in chamber T1, between times t13' and t14. Then, the device 10 switches to the expiration phase EXP between times t14 and t15. Between times t15 and t16, the device again switches to the inspiration phase INS which takes place in the same way as between times t11 and t12.

[0050] The duration of exposure to ultraviolet rays of the air in each of the chambers T1, T2 is greater than three phases of inspiration or expiration (between times t11' and t15 for chamber T1), i.e. 5.3 s. However, during these three phases, a part of the air (0.2 l) was renewed in chamber T1, between times t13' and t14, and was exposed to UV during a single phase of expiration EXP, between times t14 and t15. This part of renewed air therefore received a dose of 17.6 mJ / cm 2 < (10 x 1.76).

[0051] When the remaining volume to be aspirated is low at time t11', taking into account the previous respiratory phase, it may be planned to leave chamber T1 in communication with line 6, knowing that the air which enters through orifice II at the base of chamber T1, crosses the entire length of the latter and is therefore subject to UV.

[0052] There figure 5 illustrates the operation of the air disinfection device 10 when the physical activity of the user 1 is even more intense. In the example of the figure 5 , user 1 performs 30 respiratory cycles per minute and inspires 60 l / min (seven times the resting volume). Each phase of inspiration and expiration, between times t21 and t25, and times t25 and t26, therefore lasts 1 s, and the volume of air inspired or expired at each inspiration or expiration is 2 l.

[0053] Between times t21 and t22, all the air in chamber T1 is sucked in. At time t22, the processor PRC determines that all the disinfected air in chamber T1 has been sucked in based on the pressure measurement provided by the sensor PS, and controls the valve device EV to connect chamber T2 to line 6. At time t23, the processor PRC determines that all the disinfected air in chamber T2 has been sucked in, and controls the valve device EV to connect chamber T1 to line 6. This process is repeated once between times t23 and t25 to reach the end of the inspiration phase INS. Thus, between times T21 and t25, the device 10 carries out four inspiration phases carried out alternately in each chamber T1, T2, to provide the 2 l inspired by the user, during the inspiration phase INS of duration 1 s. Each phase of inspiration between times ti and ti+1 (i=21, 22, ...24), carried out during the inspiration phase INS therefore lasts 0.25 s. The expiration phase EXP extends over one second between times t25 and t26, the exposure phase of the chamber T1 taking place between times t24 and t26, and the exposure phase of the chamber T2 taking place between times t25 and t27. The process executed during times t21 to t25 is executed again from time t26.

[0054] In the previous example, in which the LL light source produces a light intensity of 10 mW / cm 2< , an exposure time of 0.5 s makes it possible to achieve a dose of 5 mJ / cm 2< which is still higher than the dose of 4.7 mJ / cm 2< effective for eliminating 90% of coronaviruses in particular.

[0055] In the case where the direction of air circulation in lines 6, 8 and 9, and in chambers T1, T2 is reversed, the inspiration INS and expiration EXP phases in the figures 3 , 4 et 5 are reversed.

[0056] According to one embodiment, the air introduced into the chambers T1, T2 is compressed by means of an air compressor, to increase the disinfection capacity of the device, without increasing the volume of the latter, or reducing this volume while maintaining the same air disinfection capacity. The air compressor can be coupled to the inlets I1, I2 of the chambers T1, T2 in the case where the device is used to disinfect inspired air. In this case, the valve device EV is configured to be able to close at the same time the lines 8 and 9 to the chambers T1, T2. The air compressor can be coupled to the lines 8, 9 connected to the chambers T1, T2 in the case where the device is used to disinfect exhaled air, the inlets I1, I2 being equipped with non-return valves or controlled valves to keep the chambers T1, T2 closed when the compressor raises the pressure in the chambers.

[0057] The PRC processor can be coupled to a communication circuit, for example of the Bluetooth type, to connect the processor to an external SP terminal such as a mobile phone. The PRC processor can then be configured to transmit to the SP terminal data, such as measurements relating to the user's breathing (volumes, flow rate, frequency, etc.), theoretical percentages of germs destroyed, a charge state of the BT battery, a number of hours of use of the device, etc.

[0058] It will be clear to those skilled in the art that the present invention is susceptible to various variant embodiments and various applications. In particular, the invention is not limited to a device in which the UV radiation sources are permanently active. Indeed, it may be desirable to switch off the UV radiation sources during the phases when the air is not renewed in the chambers T1, T2, that is to say during the inspiration phases in the example of the figure 2, or during the exhalation phases when the direction of air circulation in the chambers is reversed to disinfect the air exhaled by the user. Indeed, some sources such as LEDs tend to heat up. It may also be desirable to extend the duration of use of the device without having to change or recharge the BT battery. In addition, it may be sufficient to expose the air in the chambers to UV radiation only during the inspiration or expiration phases. The light power emitted by the LL source during the duration of each of the inspiration or expiration phases may be sufficient to destroy the targeted germs depending on the air flow.

[0059] The air disinfection device can have more than two chambers in parallel, in particular to be able to treat a greater air flow.

Claims

1. A method for disinfecting the air breathed in by a user, the method comprising steps of: subjecting the inside of a first chamber (T1) in communication (11) with an outside air space, to a first source (LL) of ultraviolet radiation having a wavelength able to destroy germs, subjecting the inside of a second chamber (T2) in communication (11) with the outside air space, to a second source (LL) of ultraviolet radiation, detecting times (t1-t8) when the air inhalation (INS) and expiration (EXP) breathing phases carried out by the user start, each breathing phase being associated with a forward or backward direction of circulation in which air is circulated in a pipe (4, 6) during the breathing phase, during a first forward direction breathing phase following a first backward direction breathing phase, circulating the air from the first chamber (T1) between an inner volume of a breathing mask (2) covering the mouth and the nose of the user (1) and the outside air space, the first forward direction breathing phase being followed by a second backward direction breathing phase, and wherein, during a second forward direction breathing phase following the second backward direction breathing phase, circulating the air from the second chamber T2) between the internal space of the breathing mask (2) and the outside air space.

2. The method according to claim 1, comprising a step of detecting that the air of the first chamber (T1) is fully changed before the end (t12, t25) of the first forward direction breathing phase, followed by a step of circulating the air of the second chamber (T2) alternately with the circulating of the air from the first chamber (T1), between the internal space of the respiratory mask (2) and the outside air space.

3. The method according to claim 1 or 2, comprising several alternating steps to circulate the air from the first chamber (T1) and to circulate the air from the second chamber (T2), between the internal space of the respiratory mask (2) and the outside air space, during the first forward direction breathing phase, each alternation being triggered by the detection that the air is fully changed in the first or second chamber (T1, T2).

4. The method according to one of claims 1 to 3, comprising steps of turning off the first and second ultraviolet radiation sources (LL) during each backward direction breathing phase.

5. The method according to one of claims 1 to 4, wherein: the first and second forward direction breathing phases are user inhalation phases (INS), and the first and second backward direction breathing phase are user expiration phases (EXP), or the first and second forward direction breathing phases are user exhalation phases (EXP), and the first and second backward direction breathing phase are user inhalation phases (INS).

6. The method according to one of claims 1 to 5, comprising steps of activating a fan (VT) to circulate the air during each forward direction breathing phase (INS).

7. A device for disinfecting air breathed in by a user, the device comprising: a first chamber (T1) and a second chamber (T2), in communication (11, I2) with an outside air volume and coupled by a controlled valve device (EV), to a first pipe (6) connected to the internal space of a breathing mask (2), an ultraviolet radiation source (LL) installed inside each of the first and second chambers (T1, T2), and a measurement device (PS, PRC) for determining a direction in which air circulates in the first pipe (6), the disinfecting device being configured to implement the method according to one of claims 1 to 6, the detection of the times (t1-t8) when the air inhalation (INS) and exhalation (EXP) phases start being carried out using the measuring device (PS, PRC), and the circulating of the air in the first chamber (T1) and in the second chamber (T2) being carried out using the valve device (EV).

8. The device according to claim 7, wherein each of the first and second chambers (T1, T2) comprises a ventilation device (VT) for circulating the air through the chamber (T1, T2).

9. The device according to claim 8, wherein the ventilation device comprises a pump or a fan (VT) and / or implements the Coanda effect.

10. The device according to claim 7 or 9, wherein the source (LL) of UV radiation in each of the first and second chambers (T1, T2) comprises a UV quartz tube or UV LED lamp.

11. The device according to one of claims 7 to 10, wherein the device is installed in a portable housing, including an autonomous electric power source (BT).

12. The device according to one of claims 7 to 11, wherein each of the first and second chamber (T1, T2) is associated with a compressor to increase the pressure in the chamber (T1, T2).

13. The device according to one of claims 7 to 12, wherein the UV radiation source (LL1) is installed in each of the first and second chambers (T1, T2) and configured to subject an exposure volume in the chamber (T1, T2) to a light intensity greater than or equal to 10 mW / cm2.