GB2580838A

GB2580838A - Respirator cartridges

Info

Publication number: GB2580838A
Application number: GB2005842.6A
Authority: GB
Inventors: Owen Hutchinson Thomas
Original assignee: Trilogy Medical Prot Ltd
Current assignee: Trilogy Medical Prot Ltd
Priority date: 2020-04-22
Filing date: 2020-04-22
Publication date: 2020-07-29
Anticipated expiration: 2040-04-22
Also published as: GB2580838B; GB202005842D0

Abstract

A respirator cartridge 100 that has an inlet 18, an outlet 22 and a reservoir 14 sealingly interposed between the inlet 18 and the outlet 22. One-way valves 40, 42 are respectively provided at the inlet 18 and the outlet 22 and a radiation emitter 30 is arranged to emit radiation into the reservoir 14. The reservoir 14 may be configured with a series of interconnected sub-compartments 14a, fig.4, or possibly a slidable baffle 102, such that the dwell time of air in the reservoir 14 is long enough for the radiation emitter 30 to neutralise pathogens within the air in the reservoir 14. The radiation emitter 30 may comprises an ultra-violet UV lamp, which may be a light-emitting-diode LED or an excimer lamp. The reservoir 14 may have a volume of an adult tidal breathing volume. A filter 24 may be located upstream of, and sealingly connected to, the inlet 18, where the filter 24 may comprises a microbial filter. Also, a respirator comprising: a face mask and/or an oral-nasal unit comprising an inhale aperture to which a respirator cartridge 100 is affixed, and an exhale aperture fitted a one-way exhale valve.

Description

RESPIRATOR CARTRIDGES

This invention relates to respirator cartridges and in particular, but without limitation, to antimicrobial respirator cartridges.

A respirator is a breathing apparatus worn by people when exposed to harmful environments.

Respirators can be of the "sealed" type, that is to say forming a seal around the nose and mouth of the user, and optionally around the face of the user; or they can be of the "open" type, that is to say without forming a seal against the face. The purpose of a respirator is to remove target harmful species in the air that is breathed in, and this can be accomplished in a number of ways.

In a typical FFP3 respirator, for example, there is an oral nasal unit that seals around the nose and mouth of the wearer, which oral nasal unit has at least one inhale aperture and at least one exhale aperture. A one-way valve (an exhale valve) is fitted at the exhale aperture, such that when the wearer exhales, the exhaled air is vented out through the exhale aperture via the oral nasal unit. However, when the wearer breathes in, the exhale valve closes, meaning that air can only be drawn into the oral nasal unit via the inhale aperture.

In order to safeguard the user, the inhale aperture is fitted with a filtration device. This can be a single-use item, but in many cases, the filtration device comprises a filter cartridge, which sealingly connects to the inhale aperture of the oral nasal unit via a push, bayonet or screw fitting, as the case may be.

The filter cartridge itself has an inlet and an outlet and a filter medium is interposed between the inlet and the outlet. Thus, when a user breathes in, air is drawn into the cartridge, passes through the filter medium, exits the cartridge and enters the oral nasal unit and is then breathed-in by the wearer. Upon exhalation, the air simply exits the oral nasal unit clean via the exhale valve/aperture.

One problem with filters is their efficiency against very small particles, such as viruses. Viruses often have nanometre-scale dimensions, which can make filtering them by conventional means quite difficult. The higher the filtration efficiency of the filtration medium, the greater the pressure drop tends to be across that filtration medium due to the decreased pore or perforation size of the filtration media. This can lead to excessive effort being required to breathe in through the filter cartridge. To ameliorate against this, a larger surface area of the filter medium can be used, but this can tend to increase the overall size of the cartridge, thus making the respirator less practical to wear.

A further issue with respirators is that they are classed as "Personal Protective Equipment" (PPE), and therefore are fitted to, and used only by, a single person. Moreover, even though the oral nasal unit or face mask may be user-specific PPE, (e.g. for fitting/sealing purposes), the cartridges are nevertheless generally interchangeable between respirators of the same type. However, "sharing" of respirator cartridges is ill-advised due to the risk of cross-contamination and the general inability to be able to track the overall duty cycle of a given filter cartridge if it is passed from person to person.

Accordingly, one or more sets of filter cartridges (i.e. an in-use set and a spare set) need to be issued to each user and this increases inventory.

Due to the nature of the filter medium, existing filter cartridges also have a finite shelf-life, making them expensive and/or impractical to stockpile.

A need exists for an alternative type of respirator cartridge, which addresses one or more of the above problems.

Aspects of the invention are set forth in the appended independent claim or claims. Preferred and/or optional features of the invention are set forth in the appended dependent claims.

According to an aspect of the invention, there is provided a respirator cartridge comprising an inlet, an outlet, a reservoir whose volume is of the order of the total breathing volume of a typical human and which is sealingly interposed between the inlet and the outlet, a one-way inlet valve interposed between the inlet and the reservoir, a one-way outlet valve interposed between the reservoir and the outlet, and a radiation emitter arranged to emit radiation into the reservoir.

The most notable difference between the invention and known respirator cartridges is that the "filter medium" is not of a conventional type, but is rather a radiation emitter that acts upon air within the reservoir.

Suitably, the radiation emitter is a UV light source, such as a UV lamp, a UV LED, or a UV excimer lamp.

Studies have shown that exposure to UV radiation is an effective way of sterilising air, water and surfaces. Therefore, by exposing the air within the reservoir to UV radiation, it is possible to kill pathogens, such as fungi, viruses and bacteria that are present in the air within the reservoir.

UV radiation works most effectively for sterilisation at less than about ZSSnm wavelengths ("UVC"), with around 222nm ("far-UVC") having been recently discovered to be particularly effective against viruses. 222nm UV radiation has, in fact, been shown to neutralise pathogens within a matter of seconds, as opposed to tens of seconds (or even minutes), which is the case for conventional 1550mm-UVC radiation.

The problem therefore arises as to how to ensure that the air within the reservoir is exposed to the UV radiation for a sufficient period of time, i.e. ensuring that the "dwell time" of the air within the reservoir is sufficiently long for the UV radiation to do its job.

It is generally accepted that the tidal breathing volume of a human is around 500m1, and that a typical human inhales/exhales between 12 and 20 times per minute. As such, air drawn into the reservoir in a first breath, and inhaled into the lungs in a subsequent breath, can be resident within the reservoir for between 3 and 5 seconds -if the volume of the reservoir is roughly equal to the volume of air inhaled in each breath. By making the volume of the reservoir greater than, say, 500m1, the air within it would typically be exposed to the UV radiation for between three and five seconds, which has been found to be ample time for the UV radiation (particularly far-UVC radiation) to neutralise any pathogens, and in particular, viruses, within that volume of air.

In addition, in the case of a respirator that has two filter cartridges, then the volume of the reservoir could be halved, for example to 250 millilitres for a 500 millilitre breath, because the two cartridges would work in parallel.

In one embodiment, the reservoir comprises an elongate tube with the inlet at one end and the outlet at the other. The idea behind this is to ensure that air is drawn in and removed from the reservoir in a serial/sequential manner. That is to say, air enters the reservoir via the inlet, passes along the length of the reservoir before being inhaled via the outlet at the opposite end. This ensures that the dwell time of the air is maximised. The provision of a one-way valve at the inlet and outlet also ensures that air can only flow in through the inlet and out through the outlet, thus avoiding the possibility of the user exhaling exhaled breath back into the reservoir, rather than out through the outlet valve or air exit pathway of his/her respirator (known as re-breathe).

In order to ensure that the dwell time of the air within the reservoir is sufficient for each breath, the reservoir is suitably divided into a number of sequential compartments. As such, air entering the reservoir fills the first compartment, and when that compartment is full, it passes into the next compartment and the first compartment is filled by further air. The process can continue in such a way. By providing a one-way valve between each compartment, this further ensures that the dwell time of the air within the reservoir is sufficient to enable the UV radiation to do its job.

Given that the total volume of the reservoir in most practical applications would be greater than 500m1, but possibly greater than 750m1, or even greater than 1,000m1, if the reservoir were to be formed as a tube having 2cm inner diameter, then a 500m1 reservoir would need to have the length of around 160cm. Such a tube could be accommodated by coiling it within a casing of the cartridge, but in a preferred embodiment of the invention, the interior of the cartridge comprises a serpentine pathway formed, for example, by a plastics injection moulding.

The labyrinthine pathway could extend back and forth or in a spiral within the casing of the cartridge and the design of the bottle or baffles would need to be considered to ensure that the pressure drop across the cartridge is not excessive. However, such design considerations are well within the scope of the skilled person's general knowledge.

Preferably, the serpentine pathway is formed by an injection-moulded plastics component, which is UV transparent and can, therefore, be formed as a light guide for the UV light source. In such an embodiment, it is possible to illuminate the entire volume of the cartridge by using one or just a few, UV LEDs, for example, but to have that light dispersed around the interior of the cartridge, so that it interacts with as much of the volume of air within the cartridge at once, by virtue of the light-guiding effect of the plastics injection moulding.

To safeguard against egress of the UV radiation, the exterior of the casing is preferably UV opaque.

The UV radiation is suitably provided by a UV LED or a UV lamp, such as an excimer lamp, which is preferably battery-powered. The batteries are suitably built into the cartridge itself and an on/off switch is suitably provided to enable a user to switch the UV light source on or off as needed. An indicator is preferably provided to indicate to the user whether the UV lamp is operational. The indicator could be a simply on/off indicator, but preferably incorporates a light intensity sensor, which senses the intensity of UV light within the cartridge, and indicates this to a user. This safeguards against the possibility of using a cartridge with a flat or nearly flat battery, which is technically "on", but which is not emitting sufficient UV light intensityto kill pathogens, viruses or other microbes within the air in the reservoir.

In another embodiment of the invention, a moveable baffle is located within the reservoir with the inlet on one side of the baffle, and the outlet on the other. The baffle is suitably moveable between first and second positions, and is configured to move under the action of an applied vacuum at the outlet side of the cartridge. A spring may be provided for urging the baffle towards the inlet side and the baffle suitably has a deliberate leakage pathway incorporated therein to permit air to pass through and/or around the baffle from one side of it to the other, in use.

A further advantage of the invention is that it does not rely on conventional filtration technology, so does not become clogged over time. This reduces the need to place filters periodically when they become clogged or used up. Indeed, the cartridge of the invention could be manufactured from a waterproof and/or sterilisable material such that it could be periodically cleaned, for example, using a disinfectant solution, periodically to thereby extend its duty cycle. This may also enable the cartridge to be shared between different users simply by carrying out a cleaning/sterilisation procedure between successive users.

Embodiments of the invention shall now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a perspective view of a first embodiment of a respirator cartridge in accordance with the invention; Figure 2 is a schematic front view of an embodiment of a respirator cartridge in accordance with the invention; Figure 3 is a schematic system diagram for the embodiment of the invention shown in Figures 1 and 2; Figure 4 is a schematic front view of an alternate embodiment of the invention shown in Figure 2; Figure 5 is a schematic system diagram for the embodiment shown in Figure 4; Figures 6 and 7 show how the capacity of the respirator cartridge can be adapted; Figure 8 is a schematic perspective view of another embodiment of a respirator cartridge in accordance with the invention; Figures 9-13 are schematic cross-sections of the respirator cartridge (not shown to scale) of Figure 8 showing a sequence of how it operates, in use.

Referring to Figure 1 of the drawings, a respirator cartridge 10 in accordance with the invention comprises an outer casing 12 forming a hollow interior volume 14. A cover 16 clips onto the main body 12 and has a seal 18 to form an airtight seal. The cover 16 has an inlet aperture 18, which feeds into the centre of the main body 12. A coiled baffle 20 is located within the hollow interior volume 14 such that air entering the cartridge 10 via the inlet 18 is guided in a spiral pathway through the hollow interior volume 14, until it reaches the outlet 22, which sealingly connects to the inhale aperture (not visible) of the oral nasal unit 24 of a respirator.

An optional scrim 24 covers the inlet 18 and forms a preliminary pre-filter for the cartridge 10.

In use, a user inhales through the oral nasal unit 24, which draws air in through the inlet aperture of the oral nasal unit 24, which is connected to the outlet 22 of the cartridge 10. This creates a vacuum at the inlet 22 of the cartridge, which draws air into the cartridge 10 through the inlet 18. The air flows through the spiral pathway formed by the coiled baffle 20 until it reaches the outlet 22 of the cartridge 10 and enters the oral nasal unit 24 to be breathed-in by the user.

The provision of the coiled baffle 22 ensures that the air is consumed in a serial manner, i.e. that there is a certain amount of "dwell time" within the cartridge 10 before the air is eventually expelled into the oral nasal unit 24.

Although not visible in Figure 1 of the drawings, but shown in Figure 2 of the drawings, there is a UV light source 30 located within the housing 12. The UV light source 30 illuminates the interior volume 14, thereby eradiating any air within the cartridge 10 with UV light. Suitably, the UV light is far-UVC light, more specifically, around 222nm wavelength, and this provides a sterilising function for the air contained within the cartridge 10. By illuminating the UV light source 30, and by ensuring that the air within the cartridge 10 has a certain minimum dwell time, it is possible to sterilise the air within the cartridge 10, thus rendering it safe for the user to breathe through the oral nasal unit 24.

The UV light source 30 is powered by a circuit 32, which comprises a battery and a controller therefore. An on/off switch 34 is provided on the outer casing 16, in this case, a slide switch 34, which enables the user to turn on or turn off the UV light source 30 as required.

By incorporating the on/off switch 34 into a sliding mechanism, it is possible to block the inlet 18 when the switch 34 is in the off position. This means that when the user inhales with the device in the off position, the inlet 18 is blocked, and this will be readily apparent as the user will not be able to inhale air easily, or at all. This will prompt the user to switch the device on by moving the slide switch 34 to the open position, thereby simultaneously opening the inlet 18 at the same time.

Control circuit 32 is also connected to an indicator light 36, which is formed as part of the on/off switch 34. The indicator light illuminates when the device is switched on thus indicating to the user and people nearby that the cartridge 10 is operational.

In a preferred embodiment of the invention, the circuit 32 comprises a light sensor located within the hollow interior volume 14 of the cartridge, which detects the flux/intensity of the light emitted by the UV light source 30. The light sensor is suitably connected to the indicator light 36 so that when the intensity of the light drops below a certain level, as may be the case when the batteries are running flat, the indicator light changes colour or switches off. This alerts the user to the situation where the device is technically switched on, but where the battery power is low and the sterilising effect of the UV light source 30 is not sufficient.

As previously mentioned, it is necessary to have a certain amount of "dwell time" for the air within the cartridge. In the embodiment shown in Figure 1, the baffle 20 has a spiral configuration, whereas in Figure 2 of the drawings, it has a serpentine configuration. The design of the baffle will need to be considered in detail to ensure that the pressure drop is not excessive, thereby increasing the breathing load on the user. However, it can be seen that by providing a pathway between the inlet and the outlet, rather than having the two opening into an open volume directly, it is possible to ensure that air moves in a serial fashion along the pathway between the inlet 18 and the outlet 22, thus ensuring a certain amount of dwell time.

Referring to Figure 3 of the drawings, a system diagram is shown, in which the inlet 18 is connected to the outlet 22 via a reservoir 14, namely the hollow interior volume of the cartridge 10 itself. The UV light source 30 is located within, or shines into, the volume 14, thus sterilising any air within that volume 14. Although not described previously, a one-way valve 40 is provided between the inlet 18 and the reservoir 14, and a further one-way valve 42 is provided between the reservoir 14 and the outlet 22. This ensures that the flow of air through the system is in one direction only.

Referring now to Figure 4 of the drawings, a modification to the design shown in Figure 2 is shown, whereby a series of one-way valves 44 are provided within the hollow interior volume 14. This essentially divides the flow pathway into separate compartments, which the air must pass through on its travel between the inlet 18 and the outlet 22. This further ensures that the air within the cartridge 10 has a certain minimum dwell time as it passes through the cartridge 10.

Although not readily apparent from the Figures previously described, the baffle 20 is suitably manufactured from a UV-transparent plastics material, which acts as a light guide for the UV light source 30. This is shown, in greater detail, in the system diagram of Figure 5, whereby the hollow interior volume 14 is divided into separate compartments 14a-14n, which are arranged in series with one-way valves 44 located between them. The UV light source 30 illuminates the compartments 14a-14n by way of a light guide 46 formed by the material of the baffle 20. This ensures illumination of all compartments 14a-14n by the UV light source 30, thus ensuring complete sterilisation of the air within the cartridge 10.

It will be appreciated that the volume of the compartment 14 may need to be adapted to suit different needs/requirements. This can easily be accomplished by changing the depth dimension 48 of the cartridge 10 as shown in Figures 6 and 7, whereby a relatively larger and a relatively smaller version of the housing 12 shown in Figure 1 are shown for illustration purposes only.

Referring now to Figure 8 of the drawings, an alternative embodiment of a filter cartridge 100 in accordance with the invention has a similar casing 12 and cover 16 to that previously described, a slide-on-off switch 34 and an indicator light 36 as previously described. In this embodiment, however, rather than providing a fixed baffle 20, a moveable baffle 102 is provided, which slides 104 within the hollow interior volume 14 -guided on guide rods 106. The baffle 102 is manufactured from a thin sheet of material and does not form a seal around its periphery with the interior wall 108 of the housing 12. Indeed, there may be small apertures, slots or other openings 110 provided in the baffle 102 to allow air to pass from one side of it to the other.

The purpose of the sliding baffle 102, as shown in Figures 9-13 of the drawings, is to separate the hollow interior volume 14 into sub-compartments 14x and 14y located on either side of the baffle 102.

Referring to Figures 9-13 of the drawings now, a cross-section through the cartridge 100 is shown. In Figure 9 of the drawings, it can be seen that the inlet 18 has a one-way flap valve 40 formed, which enables air to enter the hollow interior volume 14 via the inlet, but not to leave via the inlet 18.

A flap valve 42 is also provided at the outlet 42 to ensure that airflow is only from the interior volume 14 to the outlet 20.

The sliding baffle 102 is mounted on guide rods 106 and is spring biased (in this embodiment by extension springs 112) towards the inlet 18 side of the cartridge 100. The sliding baffle 102 essentially separates the hollow interior volume 14 into upstream 14x and downstream 14y sides. A small gap 114 surrounds the sliding baffle 102 thus preventing a seal from being formed between the upstream 14x and downstream 14y sides of the baffle 102 thereby. A UV light source 30 is located within the hollow interior volume 14. Figure 9 shows the initial configuration of the cartridge 100. Referring now to Figure 10 of the drawings, as a user begins to inhale 116 a vacuum is formed at the outlet 22 of the cartridge 100. The flap valve 42 thereby opens allowing air to exit the downstream side of the sliding baffle 102 into a connected oral-nasal unit (not shown). The initial phase of inhalation has a high flow rate, and thus a fairly large vacuum is created at the inlet 22, which causes the sliding baffle 102 to move in the direction shown by arrow 118. Air is thus drawn into the inlet 18 by virtue of the vacuum formed now in the upstream side 14x of the cartridge 100. Although there is some "leakage" 120 around the sliding baffle 102, because the rate of inspiration is greater than the leakage rate around the baffle 102, air is simultaneously drawn in through the inlet 18 and moves 118 the baffle 102 at the same time.

Referring now to Figure 11 of the drawings, which shows the cartridge 100 part-way through an inhalation. It can be seen that the inhalation rate 116 is now much lower, and the baffle 102 has reached the end of its extent of movement. The downstream side 14y of the hollow interior volume has been emptied, and the upstream side 14x has been filled by fresh air entering the volume 14 via the inlet 18. The springs 112 are now fully extended and because the rate of inhalation is insufficient to hold the sliding baffle 102 against the action of the springs, the system reaches a metastable equilibrium.

In Figure 12 of the drawings, the system has gone past the metastable equilibrium point, whereby the rate of inhalation is insufficient to hold the sliding baffle 102 against the action of the springs 112. The sliding baffle 102 thereby reverses its direction 118 and moves back towards the inlet side 18 of the cartridge. At this point, the inlet one-way valve 40 closes and the baffle 102 moves towards the inlet 18. This enables air that was previously in the upstream 14x side of the baffle 102 to "leak" around the baffle 102 into the downstream side. This transfers the air within the volume 14 from the upstream side to the downstream side where it is exposed to UV eradiation by the UV light source 30.

During exhale, as shown in Figure 13, the flap valve 42 fully closes, thereby sealing the outlet 22 of the cartridge 100. The exhale breath is thus vented through an exhale aperture or exhale valve 25 of the attached respirator. This exhale cycle provides sufficient time for the baffle 102 to move fully back to the start position shown in Figure 9 ready for the next inhalation cycle.

It will be appreciated that the sliding baffle configuration shown in Figures 8-13 of the drawings ensures a serial consumption of the air from the inlet to the outlet without providing a serpentine or coiled pathway, which may cause excessive pressure drop within the cartridge. Furthermore, in the event of failure, the user is still able to breathe by forcing air through the leakage pathway 120.

Claims

CLAIMS1. A respirator cartridge comprising: an inlet; an outlet; a reservoir sealingly interposed between the inlet and the outlet; a one-way inlet valve interposed between the inlet and the reservoir; a one-way outlet valve interposed between the reservoir and the outlet; and a radiation emitter arranged to emit radiation into the reservoir.
2. The respirator cartridge of claim 1, wherein the radiation emitter comprises a UV lamp.
3. The respirator cartridge of claim 1 or claim 2, wherein the radiation emitter comprises a UV-C lamp.
4. The respirator cartridge of claim 1, 2 or 3, wherein the radiation emitter comprises a far-UVC lamp.
5. The respirator cartridge of any preceding claim, wherein at least a portion of the radiation emitted by the radiation emitter comprises UV light having a wavelength of between 200 and 230nm.
6. The respirator cartridge of claim 5, wherein at least a portion of the radiation emitted by the radiation emitter comprises UV light having a wavelength of 222nm +/-5nm.
7. The respirator cartridge of any of any preceding claim, wherein the volume of the reservoir is of the order of the tidal breathing volume of an adult human.
8. The respirator cartridge of any of any preceding claim, wherein the volume of the reservoir is of the order of half the tidal breathing volume of an adult human.
9. The respirator cartridge of claim 7 or claim 8, wherein the volume of the reservoir is any one or more of the group consisting of: greater than substantially 500m1; greater than substantially 750m1; and greater than substantially 1000m1.
10. The respirator cartridge of any preceding claim, further comprising: a separator which is: located within the reservoir for dividing the interior volume of the reservoir into an upstream portion located between the inlet and the separator, and a downstream portion located between the separator and the outlet; moveable between a first position in which the volume of the upstream portion is less than the volume of the downstream portion and a second position in which the volume of the upstream portion is greater than the volume of the downstream portion; and which is configured to permit a passage of air between the upstream and downstream portions; and biasing means configured to urge the separator towards the inlet; wherein the separator is configured such that an air resistance of the inlet and/or the outlet is less than an resistance associated with the passage of air between the upstream and downstream portions.
11. The respirator cartridge of claim 10, wherein, in use, when a user inhales via the outlet: air within the downstream portion is drawn out of the reservoir via the outlet, and due to the greater air resistance associated with the passage of air between the upstream and downstream portions than the air resistance of the inlet and/or the outlet: the separator moves from the first position towards the second position against the action of the biasing means, and air is drawn into the upstream portion via the inlet.
12. The respirator cartridge of claim 10 or claim 11, wherein, in use, when a user ceases inhaling via the outlet, due to the action of the one-way valves: the separator moves from the second position towards the first position due to the action of the biasing means, and in so doing air within the upstream portion is transferred into the downstream portion of the reservoir.
13. The respirator cartridge of claim 10, 11 or 12, wherein the radiation emitter is configured to emit radiation into the downstream portion of the reservoir.
14. The respirator cartridge of claims 10 to 13, wherein the air resistance of the inlet and/or the outlet is less than the resistance associated with the passage of air between the upstream and downstream portions by virtue of any one or more of: a gap between a peripheral edge of the separator and an internal wall of the reservoir; an aperture in the separator whose area is less than the area of the outlet; and an aperture in the separator whose area is less than the area of the inlet.
15. The respirator cartridge of any of any preceding claim, wherein the reservoir comprises a series of interconnected compartments.
16. The respirator cartridge of claim 15, further comprising an opening providing fluid communication of air between adjacent compartments in the or each series of compartments and a one-way valve interposed between at least one pair of adjacent compartments.
17. The respirator cartridge of any of claims 2 to 16, wherein the UV lamp comprises an LED or an excimer lamp.
18. The respirator cartridge of any of any preceding claim, further comprising a battery for powering the radiation emitter.
19. The respirator cartridge of any of any preceding claim, further comprising a circuit for controlling the radiation emitter.
20. The respirator cartridge of claim 19, wherein the circuit comprises any one or more of: an on/off indicator; an on/off switch; a battery charge indicator; a radiation intensity sensor for detecting the radiation intensity of the radiation emitter; and a radiation intensity indicator for indicating the radiation intensity of radiation emitted by the radiation emitter.
21. The respirator cartridge of any of any preceding claim, further comprising a filter located upstream of, and sealingly connected to, the inlet.
22. The respirator cartridge of claim 21, wherein the filter comprises a microbial filter.
23. The respirator cartridge of any of any preceding claim, wherein the outlet comprises one or more formations for sealingly and detachably affixing the outlet to the inlet of a respirator or breathing apparatus.
24. A respirator comprising a face mask and/or an oral-nasal unit for forming a sealed volume around the face or nose and mouth, respectively, of a user, the face mask and/or an oral-nasal unit comprising an inhale aperture to which the respirator cartridge of any preceding is sealingly affixed, and an exhale aperture fitted with a one-way exhale valve.
25. The respirator of claim 24, further comprising a conduit or deflector fitted downstream of the exhale valve for directing exhaled air away from the face and/or eyes of the wearer.