EP4126259A1

EP4126259A1 - Test bench for testing a source of purified air and uses thereof

Info

Publication number: EP4126259A1
Application number: EP21713703.3A
Authority: EP
Inventors: Farhad ABEDINI; Frédéric HAMMEL; Ahmed Amine MAHIOUZ
Original assignee: Ethera SA
Current assignee: Ethera SA
Priority date: 2020-03-27
Filing date: 2021-03-26
Publication date: 2023-02-08
Also published as: WO2021191418A1

Abstract

The present invention relates to a test bench comprising a closed cabinet filled with polluted air, one inhaling and/or exhaling simulator and two sensors to compare concentration of polluting species in the cabinet and in air inhaled by inhaling and/or exhaling simulator.

Description

TEST BENCH FOR TESTING A SOURCE OF PURIFIED AIR AND USES

THEREOF

FIELD OF INVENTION The present invention pertains to the field of air purification. In particular, the invention relates to a test bench configured to test a source of purified air.

BACKGROUND OF INVENTION

Air pollution has become a growing concern in industrialized countries and a major health issue for everybody living on this planet.

Many devices for protecting an individual exposed to atmospheric pollution have been developed in the last years. Closed individual protection device like masks equipped with an air filter are currently marketed. For example, patent application US 2018/296864 describes a mask comprising a flow of positive pressure air creating a stream of laminar flow filtered air for supplying filtered breathing air to a subj ct’s face and excluding outside unpurified air. Other proposed solutions relate to portable or open devices arranged around the neck or placed directly under the nostrils of the individual. For example, patent application CN105757824 describes an air diffusion device placed around the neck of an individual and comprising a system for filtering the ambient air. Thus, there is a growing need for testing the devices for protecting an individual, called herein sources of purified air, to evaluate their efficiency in means of supplying purified air.

Document WO 2007/116424 discloses a test bench for testing sources of purified air, said test bench comprises a sealed container comprising air polluted with viral or bacterial species, an inhaling simulator comprising a Sheffield’s head configured to inhale air and a pump configured to simulate air inhaling. Said test bench further comprises a suction system delivering the samples of air withdrawn in different points, such as in the container and after inhalation by the head, to sterile glass bubblers to determine the concentrations of viral and/or bacterial species in said samples of air. The determination of the concentrations of viral and/or bacterial species in the air comprises simultaneously sampling air in the cabinet prior inhalation (white test) and air after inhalation (sample test), each air sample heads through a tube to bubble into a bubbler for a specific period of time, then, at the end of testing session, the solutions contained in the bubblers are moved into containers and the collected microorganisms are counted. Thus, the determination of the concentrations of viral and/or bacterial species is not performed in real-time, results in delayed determination (at least 48h) and is done in a remote location, i.e. it is not possible to measure the concentration of polluting species in the container and in the air inhaled by the head simultaneously and while testing a source of purified air in real-time. Thus, a continuous monitoring is not possible with such a device. Also, the use of bubblers does not make it possible to measure concentrations of particulate matter.

It is therefore an object of the invention to provide a test bench and a method for testing sources of purified air, to evaluate their efficiency in means of supplying purified air in real-time, with the following advantages: testing sources in a reproducible and reliable way with different kinds of polluting species, real-time determination of polluting species concentration, continuous monitoring, instantaneous leak detection, and allowing the comparison between several sources. SUMMARY

The present invention relates to a test bench comprising: a closed cabinet comprising:

• polluted air comprising at least one polluting species;

• at least one sensor S1 configured to measure the concentration of polluting species in the cabinet; at least one inhaling and/or exhaling simulator comprising:

• at least one model head simulating a face, said model head configured to inhale and/or exhale air; at least one pump configured to simulate air inhaling and/or exhaling; and • at least one sensor S2 configured to measure the concentration of polluting species in the air inhaled and/or exhaled by the model head.

In one embodiment, the at least one polluting species is selected in the group of particles, aerosols volatile organic compounds, odorous molecules, or a mixture thereof. In one embodiment, the test bench further comprising a recording device configured to record the measurements made by the sensors (S1, S2). In one embodiment, the test bench further comprising a control unit configured to control the cabinet and/or the at least one inhaling and/or exhaling simulator. In one embodiment, the test bench further comprising at least one atmospheric conditions simulator configured to simulate air movement, temperature variations and/or humidity variations in the cabinet. In one embodiment, the at least one inhaling and/or exhaling simulator is configured to simulate the inhaling and/or exhaling of a subject with an activity. In one embodiment, the test bench further comprising a mixer with a first inlet for purified or clean air, a second inlet for polluted air and an outlet in the cabinet. In one embodiment, polluted air is generated in situ in the cabinet. In one embodiment, the test bench further comprising a source of purified air configured to deliver purified air to the model head wherein said source comprises a contact mask, a contactless mask, a depollution device, a filtration device, a helmet, an air tank, or a portable air blower configured to be worn on a head, around a neck or near nostrils of a subject, or a combination thereof. In one embodiment, the test bench further comprising a source of purified air configured to deliver purified air to the model head wherein said source comprises: a pump configured to introduce polluted air from the cabinet into the source of purified air; an air purification device configured to produce purified air from the polluted air; and an air diffuser configured to deliver purified air near the inhaling and/or exhaling simulator.

The invention also relates to a method for testing a source of purified air, said method comprising the steps of: - setting up a source of purified air in a test bench of the invention; measuring the concentration of polluting species in the cabinet and the concentration of polluting species in the air inhaled and/or exhaled by the model head.

In one embodiment, the method further comprising a preliminary calibration step wherein the sensor S2 measures the same concentration of polluting species in the air inhaled and/or exhaled by the model head as the sensor S1 in the cabinet. In one embodiment, the method further comprises calculating a function of the concentration of polluting species measured by S1 and S2. In one embodiment, the method further comprises calculating a function of the time to reach a predefined concentration threshold measured by S1 and S2. In one embodiment, the method further comprises calculating a function of the concentrations measured by S 1 at a predefined time with and without a source of purified air in the cabinet. In one embodiment, polluted air is generated in situ in the cabinet, and/or by mixing clean air and polluted air. DEFINITIONS

In the present invention, the following terms have the following meanings:

“Polluting species” refers to a substance with harmful, detrimental consequences that endanger human or animal health, harms biological resources or ecosystems, affects climate change, damages property and/or causes odor nuisance. - “Breathing”: refers to the action of inhaling and exhaling.

“Coarse particles (PM₁₀-_2.5)” refers to particles with diameters larger than 2.5 μm and smaller than or equal to 10 μm.

“Fine particles (PM_2.5)” refers to particles having a diameter inferior or equal to 2.5 μm and superior to 1 μm. - “Ultra-fine particles (PM₁)” refers to particles having a diameter inferior or equal to

1 μm This also encompasses nanoparticles which have diameters less than 0.3 μm.

“Particulate matter (PM)” refers to microscopic particles suspended in the air. Particulate matter may be solid or liquid. “Source of purified air” refers to a system being configured to deliver air to a model head or a subject. A source of purified air can be an active system, i.e. a system comprising an air pulsation device, or a passive system, i.e. a system in which a subject’s breathing carries air through said system. In particular, a source of purified air can be an individual air purification device, i.e. any type of device that intents to protect individuals allowing to breath a better quality of inhaled air and/or to prevent contamination of others from contaminated individuals. Examples of individual air purification devices include but are not limited to a contact mask, a contactless mask, or a depollution device diffusing air close to the respiratory openings.

DETAILED DESCRIPTION

The following detailed description will be better understood when read in conjunction with the drawings. For the purpose of illustrating, the test bench is shown in the preferred embodiments. It should be understood, however that the application is not limited to the precise arrangements, structures, features, embodiments, and aspect shown. The drawings are not drawn to scale and are not intended to limit the scope of the claims to the embodiments depicted. Accordingly, it should be understood that where features mentioned in the appended claims are followed by reference signs, such signs are included solely for the purpose of enhancing the intelligibility of the claims and are in no way limiting on the scope of the claims.

This invention relates to a test bench.

Said test bench comprises: a closed cabinet comprising:

• polluted air comprising at least one polluting species; · at least one sensor S1 configured to measure the concentration of polluting species in the cabinet; at least one inhaling and/or exhaling simulator comprising:

• at least one model head simulating a face, said model head configured to inhale and/or exhale air; • at least one pump configured to simulate air inhaling and/or exhaling; and

• at least one sensor S2 configured to measure the concentration of polluting species in the air inhaled and/or exhaled by the model head. The at least one inhaling and/or exhaling simulator is configured to simulate the inhaling, the exhaling or the breathing of a subject.

The test bench does not comprise a source of purified air, but is configured to test a source of purified air, said source of purified air being configured to deliver air to the model head. According to one embodiment, said test bench comprises: a closed cabinet comprising:

• polluted air comprising at least one polluting species;

• at least one sensor S1 configured to measure the concentration of polluting species in the cabinet; - at least one inhaling simulator comprising:

• at least one model head simulating a face, said model head configured to inhale air;

• at least one pump configured to simulate air inhaling; and

• at least one sensor S2 configured to measure the concentration of polluting species in the air inhaled by the model head.

In inhalation mode, polluted air is introduced and/or generated in the cabinet and circulates in a source of purified air to be purified. It is then inhaled by the model head by means of a pump, through respiratory holes (i.e. nose and/or mouth). The concentration of polluting species in the cabinet is measured by the sensor S1 and the concentration of polluting species inhaled by the model head is measured by the sensor S2. The efficiency of the source of purified air is measured by comparing the concentrations measured by sensors S1 and S2. Particularly, the amount of polluting species in the inhaled air is quantified in comparison to the inhaled volume of said air. The sensor S2 provides the concentration of polluting species in an inhaled volume of air, per minute for example. The concentration, in μg/m³ is then converted into a percentage of efficiency of the source of purified air by comparing said concentration with the one measured by sensor S1. The efficiency of the source of purified air thus refers to the ability of the source to prevent ambient polluted air from contaminating the subject wearing said source. According to one embodiment, said test bench comprises: a closed cabinet comprising:

• polluted air comprising at least one polluting species;

• at least one sensor S1 configured to measure the concentration of polluting species in the cabinet; at least one exhaling simulator comprising:

• at least one model head simulating a face, said model head configured to exhale air;

• at least one pump configured to simulate air exhaling; and

• at least one sensor S2 configured to measure the concentration of polluting species in the air exhaled by the model head.

Alternatively, in exhalation mode, the air in the cabinet is directed in the opposite direction compared to the inhalation mode, i.e. the cabinet aeraulic scheme is reversed. In this mode, localization of the sensors S1 and S2 is unchanged compared to the inhalation mode. In the exhalation mode, time to reach a predefined concentration threshold or the polluting species diffusion rate is measured. In the first configuration, a concentration threshold, i.e. a chosen concentration of polluting species, is predefined according to the polluting species in the air, the concentration of polluting species in the air in the cabinet is measured by sensor S1, and the time to reach said concentration threshold in the air in the cabinet is thus determined. This measurement is performed without and with a source of purified air in the cabinet. Then, the time to reach the predefined concentration threshold without a source of purified air and the time to reach the same concentration threshold with a source are compared. This is then converted into a percentage of efficiency of the source of purified air. In the second configuration, the concentration of polluting species in the air in the cabinet is measured by sensor S1 without and with a source of purified air in the cabinet, and concentrations measured at a same time are compared. This is then converted into a percentage of efficiency of the source of purified air. For example, the concentrations measured by S1 without and with a source of purified air after 40 seconds are compared: if the concentration without said source is 100 μg.m^-3 and the concentration with said source is 60 μg.m^-3, then the efficiency of the source of purified air is 40%. The efficiency of the source of purified air thus refers to the ability of the source to prevent potentially polluted air exhaled by subject from contaminating his direct environment. This is especially interesting with a subject contaminated with a virus, for example COVID-19 as it allows to evaluate the efficiency of a source of purified air to prevent contamination of other people. In the inhalation and exhalation mode (also called breathing mode), sensor S2 may comprise 2 sensors S2’ and S2”: sensor S2’ being configured to measure the concentration of polluting species in the air inhaled by the model head and sensor S2” being configured to measure the concentration of polluting species in the air exhaled by the model head.

In all modes (inhalation, exhalation and breathing modes), the measure of concentrations is carried out in real time, thus the efficiency of the source of purified air is also measured in real time. This means that leaks and malfunctions of said source can be detected instantaneously. Also, it allows for a continuous monitoring in time of the efficiency of the source, notably upon variations in the environment inside the cabinet.

Sensors S1 and S2 are configured to measure the concentrations of polluting species simultaneously and in real time according to a measurement step defined hereafter. This real-time measurement has tremendous advantages as it allows for continuous monitoring both concentrations in time, monitoring impact of environmental simulations on both concentrations, monitoring the source’s deteroration over time to determine a working life for said source, detecting and solving leaks or defects at the source of purified air. Consequently, the test bench of the invention allows to measure the concentration of polluting species in the cabinet and in the air inhaled and/or exhaled by the model head simultaneously and while testing a source of purified air.

Furthermore, this set-up allows for a follow-up in time of the supplying of purified air. The primary aim of this set-up is to be able to repeat the tests on the same or different sources of purified air in a reproducible way. Thus, the different sources of purified air can be compared depending on their efficiency concerning the supply of purified air. In particular, this set-up encompasses two parameters for performance of source of purified air.

First parameter is the cleaning - or depolluting - performance of source of purified air. By “purified”, it is understood that the concentration of polluting species in the purified air delivered by source of purified air is smaller than in the polluted air by at least 5% (in relative value). Second parameter is the ability to isolate model head from ambient air. Indeed, depending on geometry and structure of the source of purified air, model head may inhale only purified air or a mixture of purified air with ambient air, and/or exhaled air may all flow through the source of purified air or bypass it causing leaks.

As sensor S2 measures concentration of polluting species inhaled and/or exhaled by the model head, both parameters are considered. For instance, an air pressurized bottle would supply totally purified air, but if purified air is not delivered with an airtight mask, ambient pollution may be inhaled and hinder efficiency of such source of purified air.

Herein, the term “sensor” refers to a device which measures a parameter of a sample such as concentration of polluting species in a sample of air. A sensor is different from a sampler that is only configured to withdrawn a sample from an environment without any measurement of a physical parameter.

In a preferred embodiment, the at least one sensor S1 and/or the at least one sensor S2 are located inside the closed cabinet. This allows real-time measure of polluting species concentrations. Sensors S1 and S2 are configured to measure concentrations from any of the polluting species listed herein. In a particular embodiment, sensor S1 and/or sensor S2 is selected among spectrometric sensors, diffusion sensors, electrochemical sensors, chemical sensors, biosensors or optical sensors.

According to one embodiment, biosensors include but are not limited to aerobiocollectors i.e. microbial air samplers configured for the verification and quantification of the presence of microorganisms in the air, or sensors configured to perform ATP test, i.e. configured to rapidly measure actively growing microorganisms through detection of adenosine triphosphate (ATP).

According to one embodiment, chemical sensors include but are not limited to formaldehyde sensors.

According to one embodiment, the measurement step of the sensors S1 and/or S2 ranges from 5 to 60 seconds, preferably from 10 to 30 seconds. In a preferred configuration of this embodiment, the measurement step is 10 seconds or 15 seconds. Herein “measurement step” refers to an interval of time between two successive concentration measurements.

According to one embodiment, the at least one sensor S1 is further configured to measure the temperature and/or the humidity ratio in said cabinet. In this embodiment, the atmosphere, i.e. the temperature and/or the humidity ratio, in the cabinet can be controlled. Furthermore, this sensor S1 in the cabinet can help making sure that the bench is working properly.

According to one embodiment, the cabinet has a volume ranging from 0.125 m³ to 10 m³, preferably from 1 m³ to 5 m³, more preferably from 1 m³ to 3 m³, more preferably from 2 m³ to 3 m³.

According to one embodiment, the volume of the cabinet is selected depending on the at least one polluting species. The volume of the cabinet should be big enough to comprise all the elements of the bench and not too big so that a homogeneous pollution can be created and/or measured with a desired concentration. According to one embodiment, the cabinet comprises at least one opening, and/or glovebox gloves and sleeves. This embodiment is particularly advantageous as an opening allows the user to intervene in the cabinet without disrupting the atmosphere in said cabinet. According to one embodiment, the at least one polluting species is selected in the group of particles, aerosols, volatile organic compounds (VOC), semi-volatile compounds, odorous molecules, or a mixture thereof.

According to one embodiment, examples of particles include but are not limited to: dust, pollen, coarse particles (PM10-2.5), fine particles (PM2.5), ultra-fine particles (PMi), asbestos, bacteria, bacterial spores, viruses, black carbon, particles with a size above 10 μm, or any filterable pollutant quantifiable by sensors S1 and S2. Particles may be detected based on their average size.

According to one embodiment, examples of aerosols include but are not limited to: particles, droplets, viruses, bacteria, spores, or any filterable pollutant quantifiable by sensors S1 and S2.

According to one embodiment, examples of volatile organic compounds include but are not limited to: phytosanitary products, ozone, nitrogen dioxide, carbon monoxide, pheromones, endocrine disruptors, pesticides, formaldehyde, benzene, toluene, ethyl benzene, xylene, acetaldehyde, acrolein, or any filterable pollutant quantifiable by sensors S1 and S2

According to one embodiment, examples of semi-volatile compounds include but are not limited to: pesticides, phthalates, benzopyrenes, polycyclic aromatic hydrocarbons, or any filterable pollutant quantifiable by sensors S1 and S2.

According to one embodiment, examples of odorous molecules include but are not limited to: sulfur derivatives, esters derivatives, moisture related volatiles, or any filterable pollutant quantifiable by sensors S1 and S2

According to one embodiment, the test bench further comprises a mixer with a first inlet for purified or clean air, a second inlet for polluted air and an outlet in the cabinet. This embodiment allows for a fine control of the concentration of polluting species in the polluted air introduced in the cabinet. This is particularly advantageous for small concentrations of polluting species as it enables the dilution of air with a higher concentration of polluting species in order to obtain a small concentration. According to one embodiment, polluted air is generated in situ in the cabinet.

According to one embodiment, polluted air is generated inside and/or outside of the cabinet.

In inhalation mode, polluted air is ambient in the cabinet, while the air inhaled is a purified air, i.e. purified by the source of purified air. In exhalation mode, pure air is ambient in the cabinet, while the air exhaled is generated at the back of the model head and blown into the cabinet through the airways, this air will be purified by passing through a source of purified air placed at the exit of said airways.

In a specific embodiment, both preceding embodiments are combined, meaning that polluted air comprising at least a first polluting species is generated in situ in the cabinet and polluted air comprising at least a second polluting species is generated outside of the cabinet using a mixer with a first inlet for purified or clean air, a second inlet for polluted air and an outlet in the cabinet. This is advantageous as the concentrations of each polluting species can be finely controlled.

According to one embodiment, the test bench further comprises a source of purified air wherein said source comprises a contact mask, a contactless mask, a depollution device, a filtration device, a helmet, an air tank, or a portable air blower configured to be worn on a head, around a neck or near nostrils of a subject, or a combination thereof. In this embodiment, a mask is configured to purify the air passing through it.

According to one embodiment, examples of a portable air blower include but are not limited to: a diffusion necklace, a hat or cap comprising a fan, or eyeglasses comprising air diffusers. According to one embodiment, examples of a depollution device include but are not limited to: an air curtain dustproof device.

According to one embodiment, examples of a helmet include but are not limited to: a safety helmet, a fireman helmet, or a biological individual safety equiμment. According to one embodiment, the test bench further comprises a source of purified air wherein said source comprises: a pump configured to introduce polluted air from the cabinet into the source of purified air; an air purification device configured to produce purified air from the polluted air; and an air diffuser configured to deliver purified air near the inhaling simulator.

According to one embodiment, the air purification device is a filter.

According to one embodiment, the source of purified air comprises two pumps: one for simulating inhaling and one for simulating exhaling. According to one embodiment, the source of purified air comprises at least one flowmeter configured to measure and/or control the flow rate of purified air introduced in the source of purified air. In this embodiment, said flowmeter may be included in the pump of said source.

According to one embodiment, the source of purified air comprises at least one flowmeter configured to measure and/or control the flow rate of purified air delivered by the source of purified air to the inhaling and/or exhaling simulator.

According to one embodiment, the source of purified air comprises an additional sensor configured to measure the concentration of polluting species in the air delivered by said source. Said sensor is located between the source and the model head to quantify the difference between the inhaled air and the purified air.

According to one embodiment, the source of purified air is configured to receive and filtrate air. According to one embodiment, the frequency of the inhalation and/or exhalation is ranging from 1 to 100 inhalations (or exhalations) per minute, preferably from 2 to 50 inhalations (or exhalations) per minute more preferably from 8 to 30 inhalations (or 8 to 30 exhalations) per minute. According to one embodiment, the volume of the inhalation and/or exhalation is ranging from 0.1 to 6 L, preferably from 0.3 to 2 L.

According to one embodiment, the flow rate of the inhalation and/or exhalation is ranging from 10 to 30 L/min, preferably from 15 to 25 L/min.

According to one embodiment, the at least one inhaling and/or exhaling simulator is configured to simulate the inhaling and/or exhaling of a subject with an activity. In this embodiment, activity may refer to standing, lying, sitting, walking, running and/or sleeping. The activity of a subject corresponds to a determined frequency/volume of the inhalation and/or exhalation.

According to one embodiment, the frequency and/or volume of the inhalation and/or exhalation is controlled.

According to one embodiment, the at least one inhaling and/or exhaling simulator comprises at least one flowmeter configured to measure and/or control the flow rate or the volume of air inhaled and/or exhaled by the model head. This embodiment enables to make sure that the inhaling and/or exhaling is well imitated, and to obtain a reproducible test.

According to one embodiment, the at least one model head is further configured to exhale air. This embodiment defines the inhaling and/or exhaling simulator as being a breathing simulator. In this embodiment, the at least one model head is configured to breathe the air in the cabinet. This embodiment is particularly advantageous when the source of purified air to be tested is a closed device, such as for example a mask.

According to one embodiment, the at least one inhaling and/or exhaling simulator is configured to simulate the breathing of a subj ect with an activity. In this embodiment, activity may refer to standing, lying, sitting, walking, running and/or sleeping. The activity of a subject corresponds to a determined frequency/volume of the breathing.

According to one embodiment, the at least one model head simulates airways such as for example a nose and/or a mouth. Thus, the at least one inhaling and/or exhaling simulator is configured to simulate inhaling and/or exhaling through the nose and/or the mouth.

According to one embodiment, the at least one model head simulates a human face. In particular, the at least one model head simulates the face of an adult, a child or a baby.

According to one embodiment, the at least one model head simulates a face having the features of any ethnic group such as for example Caucasian, Asian, African, Arabic, Caribbean.

According to one embodiment, the at least one model head simulates a face of any age from a newborn to 100 years old.

According to one embodiment, the at least one model head simulates a hairless face or a face having any stage of hairiness such as for example a mustache, a beard, side whiskers, a goatee, or a combination thereof.

According to one embodiment, the at least one model head is made of silicone or polystyrene.

According to one embodiment, the pumps described herein are selected among mechanical pumps, peristaltic pumps, or piezoelectric pumps. According to one embodiment, the test bench further comprises at least one atmospheric conditions simulator configured to simulate air movement, temperature variations and/or humidity variations in the cabinet. In this embodiment, air movement may refer to a lateral wind, frontal wind, downwind, turbulences or a combination thereof. In this embodiment, the atmospheric conditions simulator may be a fan. In this embodiment, the humidity variations make it possible to simulate a rain of variable intensity. According to one embodiment, the test bench further comprises a recording device configured to record the measurements made by the sensors (S1, S2). In this embodiment, the measurements made by the sensors (S1, S2) can be saved in an electronic device, said electronic device can be internal or external to the cabinet. According to one embodiment, the test bench further comprises a control unit configured to control the closed cabinet and/or the at least one inhaling and/or exhaling simulator.

In an inhalation configuration of this embodiment, the control unit can control and/or measure:

- the atmosphere, i.e. the temperature, the concentration of polluting species and/or the humidity ratio, in the cabinet, and/or

- the frequency and/or volume of the inhaling of the at least one inhaling simulator.

In an exhalation configuration of this embodiment, the control unit can control and/or measure:

- the atmosphere, i.e. the temperature, and/or the humidity ratio, in the cabinet, and/or

- the concentration of polluting species, the frequency and/or volume of the exhaling of the at least one exhaling simulator.

Controlling the temperature, the concentration of polluting species and/or the humidity ratio in the cabinet allows for a reproducible test. Thus, several sources of purified air can be tested and compared in order to know which is the most efficient concerning purified air supplying.

In a specific configuration of this embodiment, all electronic components of the test bench (i.e. pumps, sensors, pollution generator, etc) are controlled by the control unit, to be adjusted to appropriate values by external keyboard and control panel. This embodiment is particularly advantageous as an opening allows the user to intervene in the cabinet without disrupting the atmosphere in said cabinet, i.e. without disrupting the aeraulic flow or the concentration of polluting species that an opening of the test bench would dilute. According to one embodiment, the control unit controls the polluted air generation, i.e. the introduction of polluted air in the cabinet and/or the generation of polluted air in the cabinet. In this embodiment, the polluted air can be generated by mixing clean air and polluted air in the cabinet. According to one embodiment, the control unit is a computer, a smartphone, or any electronic device.

According to one embodiment, all electronic components (i.e. pumps, sensors, pollution generator, ... ) are controlled by a computerized unit, to be adjusted to appropriate values by external keyboard and control panel. This embodiment is particularly advantageous as an opening allows the user to intervene in the cabinet without disrupting the atmosphere in said cabinet.

According to one embodiment, the control unit is configured to control the closed cabinet and/or the at least one inhaling and/or exhaling simulator using wired connection or wireless connection, such as for example WiFi or Bluetooth. According to one embodiment, the control unit is external to the cabinet.

The invention also relates to a method for testing a source of purified air.

Said method comprises the steps of: setting up a source of purified air in a test bench as described here above; measuring the concentration of polluting species in the cabinet and the concentration of polluting species in the air inhaled and/or exhaled by the model head.

According to one embodiment, the method further comprises a preliminary calibration step.

In an inhalation configuration of this embodiment, the sensor S2 measures the same concentration of polluting species in the air inhaled by the model head as the sensor S1 in the cabinet, and/or the same time to reach a predefined concentration threshold is measured by both sensors S1 (in the cabinet) and S2 (in the air exhaled by the model head). In inhalation mode, before setting up the source of purified air, the concentration of polluting species in the cabinet is measured by the sensor S1 while the concentration of polluting species in the air inhaled by the model head is measured by the sensor S2. When said concentrations are equal to one another, then the test bench is deemed to be calibrated. In a particular calibration step, sensors S1 and S2 are first used in clean air, i.e. without polluting species source, then used with a determined concentration of polluting species, allowing to control the response of sensors over a large range of polluting species from zero to high polluting species concentration.

In a first exhalation configuration of this embodiment, the same time to reach a predefined concentration threshold is measured by both sensors S1 (in the cabinet) and S2 (in the air exhaled by the model head). When said times are equal to one another, then the test bench is deemed to be calibrated. In a second exhalation configuration of this embodiment, concentrations of polluting species are measured by both sensors S1 (in the cabinet) and S2 (in the air exhaled by the model head), and when the same concentration is reached at the same time, then the test bench is deemed to be calibrated. In a particular calibration step, sensors S1 and S2 are first used in clean air, i.e. without polluting species source, then used with a determined concentration of polluting species in the exhaled air, allowing to control the response of sensors over a large range of polluting species from zero to high polluting species concentration. This embodiment is particularly advantageous as a calibration step enables to repeat the tests on the same or different sources of purified air in a reproducible and reliable way. The different sources of purified air can then be compared depending on their efficiency concerning the supplying of purified air.

According to one embodiment, the method further comprises calculating a function of the concentration of polluting species measured by S1 and S2. The method therefore aims to evaluate the efficiency of the source of purified air.

According to one embodiment, the method further comprises calculating a percentage of air purified by the source of purified air from the concentration of polluting species in the cabinet and the concentration of polluting species in the air inhaled by the model head. This corresponds to a ratio between of the concentration of polluting species in the air inhaled or breathed on the concentration of polluting species in the air that would have inhaled or breathed without the source of purified air.

According to one embodiment, the method further comprises calculating a function of the concentration of polluting species measured by S1 and S2 in time. This embodiment is particularly advantageous as it allows to follow the evolution over time of the depollution of the air in the cabinet. The method therefore aims to evaluate the efficiency in time of the source of purified air.

According to one embodiment, the method further comprises calculating a function of the time to reach a predefined concentration threshold measured by S1 and S2.

According to one embodiment, the method further comprises calculating a percentage of air purified by the source of purified air from the time to reach a predefined concentration threshold in the air exhaled by the model head and the time to reach a predefined concentration threshold in the cabinet. According to one embodiment, the method further comprises calculating a percentage of air purified by the source of purified air from the concentration of polluting species in the cabinet at a predefined time measured without said source in the cabinet and measured with said source in the cabinet. For example, the concentration measured by S1 without a source of purified air at 40 seconds of experiment is 100 μg.m^-3 and the concentration measured by S1 with a source of purified air at the same time is 60 μg.m^-3, then the efficiency of the source of purified air is 40%.

According to one embodiment, the method further comprises calculating a function of the concentrations measured by S 1 at a predefined time with and without a source of purified air in the cabinet. According to one embodiment, polluted air is generated in situ in the cabinet, and/or by mixing clean air and polluted air.

The invention also relates to the use of a test bench of the invention for testing a source of purified air. DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic representation of the test bench of the invention according to a first embodiment.

Figure 2 is a schematic representation of the test bench of the invention according to a second embodiment in which the test bench further comprises a source of purified air.

Figure 3 shows the efficiency as a function of time of different sources of purified air tested in the test bench of the invention: none (dotted line), IBLE device (solid line), 3M mask (semi-dotted line), taped 3M mask (double line).

Figure 4 shows the efficiency as a function of time of a surgical mask tested in the test bench of the invention in different positions: positioned under the nose (A - dotted line), non-adjusted on nose and mouth (B - solid line), adjusted on nose and mouth (C - semi-dotted line).

Figure 5 shows the efficiency as a function of time of different sources of purified air tested in the test bench of the invention in position C (adjusted on nose and mouth): homemade mask (double line), UN S- 1 mask (solid line), surgical mask (semi-dotted line),

FFP2 mask (dotted line).

Figure 6 shows the different positions (A-D) of a surgical mask on a model head as used in example 4.

Figure 7 shows the efficiency as a function of time of a FFP2 mask tested in the test bench of the invention in exhalation mode: measurement without the mask (dashed line) and measurement with the mask (solid line).

While various embodiments have been described and illustrated, the detailed description is not to be construed as being limited hereto. Various modifications can be made to the embodiments by those skilled in the art without departing from the true spirit and scope of the disclosure as defined by the claims. ILLUSTRATIVE EMBODIMENTS OF THE INVENTION

In a first embodiment, as shown in Figure 1, the test bench 1 comprises: a closed cabinet 11 comprising:

• polluted air comprising at least one polluting species;

• a sensor S1 configured to measure the concentration of polluting species in the cabinet 11; an inhaling and/or exhaling simulator 12 comprising:

• a model head 121 simulating a face;

• a pump 122 configured to simulate air inhaling and/or exhaling; and

• a sensor S2 configured to measure the concentration of polluting species in the air inhaled by the model head 121.

In this embodiment, air, in particular polluted air (PA), is introduced (dotted line) and/or generated (solid line) in the cabinet 11 and is then inhaled by the model head 121 by means of the pump 122. The concentration of polluting species in the cabinet 11 is measured by the sensor S1 and the concentration of polluting species in air inhaled (IA) by the model head 121 is measured by the sensor S2.

This embodiment is particularly advantageous as it allows a calibration of the test bench 1 by checking that the concentration measured by the sensor S1 is the same as the one measured by the sensor S2.

In an exhalation mode of this embodiment, air, in particular polluted air (PA), is introduced and/or generated at the back of the model head 121, and is then exhaled by the model head 121 by means of the pump 122. The concentration of polluting species in air exhaled by the model head 121 is measured by the sensor S2, and the concentration of polluting species in the cabinet 11 is measured by the sensor S1. A concentration threshold is predefined and the time to reach said concentration threshold is then determined by the monitoring of sensors S1 and S2. This embodiment is particularly advantageous as it allows a calibration of the test bench 1 by checking that the time to reach said concentration threshold measured by the sensor S 1 is the same as the one measured by the sensor S2.

In a second embodiment, as shown in Figure 2, the test bench 1 comprises: - a closed cabinet 11 comprising:

• polluted air comprising at least one polluting species;

• a sensor S1 configured to measure the concentration of polluting species in the cabinet 11; an inhaling and/or exhaling simulator 12 comprising: · a model head 121 simulating a face;

• a pump 122 configured to simulate air inhaling and/or exhaling; and

• a sensor S2 configured to measure the concentration of polluting species in the air inhaled by the model head 121; and a source of purified air 13 comprising an air diffuser 131. In this embodiment, air, in particular polluted air (PA), is introduced (dotted line) and/or generated (solid line) in the cabinet 11 and circulates in a source of purified air 13 to be purified, i.e. so that the concentration of polluting species in the air decreases or becomes null. Purified air (A) is then delivered near the model head 121 using a diffuser 131 and inhaled by said model head 121 by means of the pump 122. Depending on the disposition of source of purified air - diffuser near mouth and nose, diffuser applied on the face... - polluted air (PA) may be inhaled also (semi dotted line), leading to inhalation of a mixture of polluted air (PA) and purified air (A). The concentration of polluting species in the cabinet 11 is measured by the sensor S1 and the concentration of polluting species in air inhaled (IA) by the model head 121 is measured by the sensor S2. The efficiency of the source of purified air 13 is measured by comparing the concentrations measured by sensors S1 and S2.

In an exhalation mode of this embodiment, air, in particular polluted air (PA), is introduced and/or generated at the back of the model head 121, is then exhaled by the model head 121 by means of the pump 122, and circulates in a source of purified air 13 to be purified, i.e. so that the concentration of polluting species in the air decreases or becomes null. Purified air (A) is then delivered in the cabinet 11. In practice, a concentration threshold is predefined and the time to reach said concentration threshold in the cabinet is determined first without a source of purified air and then with a source of purified air. The efficiency of the source of purified air 13 is measured by comparing the times determined by sensors S1 and S2. Alternatively, the concentration of polluting species in the cabinet is measured without a source of purified air 13, then with a source of purified air 13, and the concentrations measured at a same predefined time are compared. In this case, the efficiency of the source of purified air 13 is measured by comparing said concentrations. This embodiment is particularly advantageous as it is possible to determine the efficiency of a source of purified air 13 in a reproducible way. It is then possible to compare different sources of purified air 13 depending on their efficiency concerning the purification of polluted air

While various embodiments have been described and illustrated, the detailed description is not to be construed as being limited hereto. Various modifications can be made to the embodiments by those skilled in the art without departing from the true spirit and scope of the disclosure as defined by the claims.

EXAMPLES The present invention is further illustrated by the following examples.

A test bench has been set up with the following elements.

A closed cabinet of 3 m³ has openings (windows) to install objects in the cabinet and gloves (like in a glovebox) allowing manipulation of objects inside the cabinet without contact of the operator with polluted air during operation, and allowing to keep stable and constant experimental conditions in the cabinet.

Sensors S1 and S2 are Honeywell HPM Series Particulate Matter Sensors. The model head is in polystyrene (supplied by Rayher Hobby) or in silicone (supplied by LK LANKIZ). A pump is connected to mouth and nose of the model head to simulate air inhaling.

Example 1: Calibration step Particulate matter 2.5 (PM 2.5) is used as pollutant at a concentration of 500 pg.m ³: a particle diffuser is used to generate particulate matter (PALAS RGB 1000, standard particles according to ISO 12103-1 A3 MEDIUM). Particulate matter can also be generated in the cabinet by cigarette smoke, incense or any material combustion.

During inhalation, concentration of pollutant is recorded by sensor S1 in the cabinet and sensor S2 in inhaled air for approximately 25 minutes (1400 seconds). Comparison of records show that concentrations are identical, demonstrating that calibration of the test bench is correct (Figure 3, dotted line: efficiency is zero in average).

Example 2: Comparison of sources of purified air, PM 2.5.

Several sources of purified air were set up in the test bench and compared under the same conditions: type and concentration of polluting species, inhalation.

Efficiency of a source of purified air can be defined by .

When E equals 100%, inhaled air does not contain any pollutant and source of purified air is excellent. Efficiency is measured continuously during 1400 seconds, then averaged to yield result reported in Table 1. Results reported in Table 1 were measured using a polystyrene model head.

Table 1 below lists configurations in which experiments have been performed.

Table 1

The following sources of purified air have been tested:

3M mask (3M Health Care Particulate Respirator and Surgical Mask 1860) is a disposable contact mask configured to protect the user from particulate matter. 3M mask was used in two distinct configurations: placed on the face of the model head, and taped to the face of the model head so as to prevent air from flowing between mask and head;

Ible Airvida device (supplied by IBLE) is a device wearable around the neck of an individual comprising an ionizer;

- R-PUR Nano Light mask (supplied by R-PUR)) is a contact mask comprising a particle filter (R-PUR Nano);

VOGMASK (supplied by VOGMASK) mask is a contact mask comprising a particle filter;

- EOS (supplied by Hyundai) device is an active system for purifying air wearable around the neck of an individual and comprising a filter (HEP A filter) and an ionizer.

One can observe that significant differences in concentration of polluting species in inhaled air are measured (Figure 3). The test bench allows for an efficient comparison of sources of purified air.

Furthermore, in the case of the 3M mask, the test bench allows for an efficient comparison of different implementation conditions. Indeed, significant differences in concentration of polluting species in inhaled air are measured between the 3M mask and the taped 3M mask (Figure 3, semi-dotted line and double line). This may be due to bad contact between the mask and the face of the model head when said mask is simply placed on said face, causing leaks of polluted air. Testing a source of purified air in the test bench of the invention can help assessing improvements that have to be done on a device in order to decrease the concentration of polluting species in inhaled air.

Better results have been achieved using a model head made of silicone as it more accurately mimics the reality of a human face. Indeed, in the case of the 3M mask, an efficiency of 31 % was obtained with a silicone head vs 21 % with a polystyrene head. Example 3: External source of polluting species.

In this example, a continuous flow, using a particle diffuser (PALAS RGB 1000, standard particles according to ISO 12103-1 A3 MEDIUM), is set up in the cabinet: inflow of 5 L/minute is introduced via inlet (20) in the cabinet with a concentration of polluting species of 500 μg.m^-3, and an outflow of 5 L/minute is extracted from the cabinet via exhaust (30), corresponding to a stationary state. With this configuration, concentration of polluting species in the cabinet is more stable. Concentration of polluting species in the inflow may be adjusted to increase or decrease polluting species concentration in the cabinet in transient conditions and/or to reach stationary conditions quickly. Example 4: Comparison of sources of purified air, PM 1

Calibration step was performed as in example 1, using PM1 as the polluting species (referred as example 4_cal). Several sources of purified air were then set up in the test bench and compared under the same conditions: type and concentration of polluting species, inhalation. For each source of purified air, different positions on the model head were studied (shown in Figure 6):

- Positioned under the nose (i.e. not covering the nose, position A),

- Positioned on both nose and mouth and unadjusted (position B),

- Positioned on both nose and mouth and adjusted (position C), - Taped on a pipe to reproduce a configuration with no leaks (position D).

Ultra-fine particles (PM 1) is used as pollutant: a particle diffuser is used to generate particulate matter (PALAS RGB 1000, standard particles according to ISO 12103-1 A3 MEDIUM).

Efficiency of a source of purified air can be defined by . When E equals 100%, inhaled air does not contain any pollutant and source of purified air is excellent. Efficiency is measured continuously during 1400 seconds, then averaged to yield result reported in Table 2. Results reported in Table 2 were measured using a polystyrene model head. Table 2 below lists configurations in which experiments have been performed.

The following sources of purified air have been tested:

FFP2 mask; - Surgical mask;

Category 1 cloth mask (UNS-1);

Category 2 cloth mask (UNS-2), i.e. Homemade cloth mask.

One can observe that, for the same position, significant differences in concentration of polluting species in inhaled air are measured (figures 4 and 5). The test bench allows for an efficient comparison of sources of purified air.

Furthermore, for each source of purified air, the test bench allows for an efficient comparison of different implementation conditions. Indeed, significant differences in concentration of polluting species in inhaled air are measured between position A-D (Figure 4, surgical mask). Position A offers no protection to the subject wearing a mask as it does not cover the nostrils making the subject inhale polluted air. On the opposite, position D is the most efficient configuration and makes it possible to judge the efficiency of the filtering means included in the mask. Indeed, without leaks, the efficiency of a source of purified air is equal to that of its filtering means. Comparison between the results obtained for positions B and C allows to judge the importance of a good fit of the mask on the face. Indeed, a bad fit is synonymous to leaks and therefore leads to poor effectiveness of the mask used.

On Figure 5, when comparing sources of purified air in position C, one can observe that a UNS-1 mask is more efficient that a surgical mask. This is due to a better contact between the UNS-1 mask and the face of the model head compared to the surgical mask, notably on the sides where leaks happen.

Thus, testing a source of purified air in the test bench of the invention can help assessing differences in efficiency between several sources of purified air and improvements that have to be done on a device or positioning o the face in order to decrease the concentration of polluting species in inhaled air.

Table 2

Example 5: Measure of VOC concentration.

Calibration step was performed as in example 1, using ethanol as the polluting species (referred as example 5_cal).

Ethanol is diffused in the chamber to generate pollution, said pollution being homogenized with fans placed in the four corners of the closed cabinet.

A FFP3 full face mask (with new filter cartridge) is then set up in the test bench as the source of purified air in two configurations:

Positioned on both nose and mouth,

Taped on a pipe to reproduce a configuration with no leaks. Efficiency of the source of purified air can be defined by .

When E equals 100%, inhaled air does not contain any pollutant and source of purified air is excellent. Efficiency is measured continuously during 1400 seconds, then averaged to yield result reported in Table 3.

Results reported in Table 3 were measured using a polystyrene model head. Table 3 below lists configurations in which experiments have been performed.

One can observe that significant differences in concentration of polluting species in inhaled air are measured (table 3). The test bench allows for an efficient comparison of different implementation conditions and assessing the efficiency of the FFP3 mask in real conditions (position covering the face) compared to theoretical conditions with no leaks (taped position). Without leaks, the efficiency of the FFP3 mask is equal to that of its filtering means whereas, in real conditions an important decrease of efficiency can be noted, showing that leaks are present. Thus, comparison between the results obtained for both positions allows to judge the efficiency of the FFP3 mask in real conditions.

Thus, testing a source of purified air in the test bench of the invention can help assessing differences in efficiency between theoretical and real conditions, and improvements that have to be done on a device or positioning o the face in order to decrease the concentration of polluting species in inhaled air.

Example 6: Exhalation mode.

Particulate matter 1 (PM 1) is used as pollutant: a particle diffuser is used to generate particulate matter (PALAS RGB 1000, standard particles according to ISO 12103-1 A3 MEDIUM). Sensor S1 measures the concentration of PM 1 in the air in the cabinet while sensor S2 measures the concentration of PM 1 in the air exhaled by the model head.

Two measurements are performed: a first measurement is performed without a source of purified air in the cabinet (referred as example 6_cal), and a second measurement is performed with a FFP2 mask set up in the test bench as the source of purified air. Then, concentrations of PM 1 measured without the source of purified air and with the source are compared. This is then converted into a percentage of efficiency of the source of purified air.

Results reported in Table 4 were measured using a polystyrene model head.

Table 4 below lists configurations in which experiments have been performed. Also, the concentration of PM 1 measured at 40 seconds with the FFP2 mask is inferior than the one measured without the FFP2 mask (Figure 7). It is clear that wearing the FFP2 mask reduces diffusion of polluting species exhaled in the cabinet.

It is thus possible to compare several sources of purified air by conducting the same experiment and comparing the time to reach the concentration threshold for all said sources.

Table 4

REFERENCES

I - Testbench

II - Cabinet

12 - Inhaling and/or exhaling simulator 121 - Model head

122 - Pump

13 - Source of purified air 131 - Air diffuser S1 - Sensor S1 S2 - Sensor S2

Claims

1. A test bench (1) comprising: a closed cabinet (11) comprising: · polluted air comprising at least one polluting species;

• at least one sensor S1 configured to measure the concentration of polluting species in the cabinet (11); at least one inhaling and/or exhaling simulator (12) comprising:

• at least one model head (121) simulating a face, said model head (121) configured to inhale and/or exhale air;

• at least one pump (122) configured to simulate air inhaling and/or air exhaling; and

• at least one sensor S2 configured to measure the concentration of polluting species in the air inhaled and/or exhaled by the model head (121).

2. The test bench (1) according to claim 1, wherein the at least one polluting species is selected in the group of particles, aerosols volatile organic compounds, odorous molecules, or a mixture thereof.

3. The test bench (1) according to any one of claim 1 or 2, said test bench (1) further comprising a recording device configured to record the measurements made by the sensors (S1, S2).

4. The test bench (1) according to any one of claims 1 to 3, said test bench (1) further comprising a control unit configured to control the cabinet (11) and/or the at least one inhaling and/or exhaling simulator (12).

5. The test bench (1) according to any one of claims 1 to 4, said test bench (1) further comprising at least one atmospheric conditions simulator configured to simulate air movement, temperature variations and/or humidity variations in the cabinet (11).

6. The test bench (1) according to any one of claims 1 to 5, wherein the at least one inhaling and/or exhaling simulator (12) is configured to simulate the inhaling and/or exhaling of a subject with an activity.

7. The test bench (1) according to any one of claims 1 to 6, said test bench (1) further comprising a mixer with a first inlet for purified or clean air, a second inlet for polluted air and an outlet in the cabinet (11).

8. The test bench (1) according to any one of claims 1 to 6, wherein polluted air is generated in situ in the cabinet (11).

9. The test bench (1) according to any one of claims 1 to 8, said test bench (1) further comprising a source of purified air (13) wherein said source comprises a contact mask, a contactless mask, a depollution device, a filtration device, a helmet, an air tank, or a portable air blower configured to be worn on a head, around a neck or near nostrils of a subject, or a combination thereof.

10. The test bench (1) according to any one of claims 1 to 8, said test bench (1) further comprising a source of purified air (13) wherein said source comprises: a pump configured to introduce polluted air from the cabinet (11) into the source of purified air (13); an air purification device configured to produce purified air from the polluted air; and - an air diffuser (131) configured to deliver purified air near the inhaling and/or exhaling simulator (12).

11. A method for testing a source of purified air (13), said method comprising the steps of: setting up a source of purified air (13) in a test bench (1) according to any one of claims 1 to 8; measuring the concentration of polluting species in the cabinet (11) and the concentration of polluting species in the air inhaled and/or exhaled by the model head (121).

12. The method according to claim 11, wherein said method further comprising a preliminary calibration step.

13. The method according to claim 12, wherein the sensor S2 measures the same concentration of polluting species in the air inhaled by the model head (121) as the sensor S1 in the cabinet (11).

14. The method according to claim 12, wherein the same time to reach a predefined concentration threshold is measured by both sensors S1 and S2.

15. The method according to any one of claim 11 to 14, wherein said method further comprises calculating a function of the concentration of polluting species measured by S1 and S2.

16. The method according to any one of claim 11 to 14, wherein said method further comprises calculating a function of the time to reach a predefined concentration threshold measured by S1 and S2.

17. The method according to any one of claim 11 to 14, wherein said method further comprises calculating a function of the concentrations measured by S1 at a predefined time with and without a source of purified air in the cabinet.

18. The method according to any one of claims 11 to 17, wherein polluted air is generated in situ in the cabinet (11), and/or by mixing clean air and polluted air.