GB2609593A

GB2609593A - Portable air filtering device and face mask therefor

Info

Publication number: GB2609593A
Application number: GB2104717.0A
Authority: GB
Inventors: Lawton Michael
Original assignee: Oxlabs Ltd
Current assignee: Oxlabs Ltd
Priority date: 2021-04-01
Filing date: 2021-04-01
Publication date: 2023-02-15
Also published as: GB202104717D0

Abstract

A portable air filtering device 10 directs filtered air to a person and comprises a housing including a cylindrical body portion (12, fig 1) and a head portion (14) connected to the body. Air is conveyed through an air inlet 16 in the housing through a filter 30 within the housing to an outlet (18) at a distal end of the head portion via a motorised 34 impeller 36 in the housing. The head portion is rotatably connected to the body to allow rotation through substantially 360 degrees about a longitudinal axis of the housing for directing the flow of the filtered air during use. The air outlet may comprise a hollow elongate nozzle 18b pivotable between a first and second position for directing filtered air longitudinally or laterally out of the device, or at an angle at one or more intermediate positions therebetween. The filter may comprise a HEPA and carbon filter. The device may be powered by a rechargeable battery 26. A display may be provided on the side of the housing displaying information about air quality. The device may provide filtered air to a user worn mask (fig 5), a pushchair (fig 15) or cot (fig 13).

Description

PORTABLE AIR FILTERING DEVICE AND FACE MASK THEREFOR

The present invention relates to a portable air filtering device for directing filtered air to a person, and to a face mask for receiving filtered air from a portable air filtering device.

BACKGROUND TO THE INVENTION

The quality of air breathed by people is known to affect their health, in that lower air quality statistically correlates with worse health in a population. Breathing polluted air has been linked to the development of inter aria respiratory ailments (e.g. asthma), cardiovascular disease and lung cancer.

Air quality is affected by various factors, including but not limited to the amounts of any harmful gases in the air, and the amount of particulate matter in the air, such as pollen.

Pollutants or harmful emissions are generally present at higher levels in towns and cities due to higher traffic levels, for example, which reduces air quality. Examples of harmful pollutants include carbon monoxide (CO), nitrogen oxides (N04, sulphur oxides (504, hydrocarbons (such as polycyclic aromatic hydrocarbons (PAHs)) and other volatile organic compounds (VOCs).

Some mains-powered indoor fans or air purifiers include a filter to reduce levels of certain contaminants in the air in a room, for example. However, such fans or purifiers are generally bulky and take time to filter contaminants/pollutants from air in the room, so any occupant(s) of the room still end up breathing in air of reduced quality in the meantime.

In view of the Covid-19 pandemic, it has become relatively commonplace to wear a face mask to minimise the spread of airborne viruses and other contagions, particularly when indoors or in an enclosed space. However, a basic N95 passive filter-only mask provides no protection against harmful pollutants such as those listed above, and does not prevent a person from inhaling airborne contagions such as Covid-19.

A passive filter mask requires the wearer to inhale and exhale through a filter material, which can cause moisture to build-up during use. This can make wearing the mask uncomfortable, particularly in hot and/or high humidity conditions. Wearing glasses at the same time as wearing the mask can lead to the glasses fogging up each time the wearer breathes out. In addition, some people find the sensation of wearing a mask to be inherently uncomfortable, for example because they feel it restricts their breathing. Similarly, it is unsuitable for a baby or young child to wear a face mask.

More sophisticated face masks are available which incorporate an air filtration system. However, with these additional elements in the face mask, it becomes very bulky and too heavy to be worn around the face for any length of time. Such a mask is also poorly suited for a person to carry out vigorous exercise whilst wearing the mask. The amount of filter material is also substantially constrained by the weight that can be comfortably It is an object of the present invention to reduce or substantially obviate the aforementioned problems.

STATEMENT OF INVENTION

According to the present invention, there is provided a portable air filtering device for directing filtered air to a person, the device comprising a housing including a body portion and a head portion (or top cap) which is connected to the body portion, an air inlet in the body portion for air to enter the housing, an air filter within the body portion for filtering air received from the air inlet, an impeller in the housing or body portion for conveying or drawing air through the air inlet and air filter, and a motor for powering the impeller, and an air outlet at a distal end (or top) of the head portion of the housing for receiving filtered air under positive pressure from the impeller, in which the head portion is rotatably connected to the body portion, or the air outlet is rotatably connected to the head portion, to allow rotation through substantially 360 degrees about a longitudinal axis of the housing for directional flow of the filtered air during use.

This can be used to supply filtered or purified air to a person, or in the direction of a person. This is particularly useful to minimise the exposure risk for airborne contagions such as Covid-19. It is also useful more generally to help minimise the amount of toxic gases like NO and SO,, pollutants and/or minute particles which are breathed in by a person, particularly in an urban environment.

The term portable is intended to mean that the device is easy for one person to carry or move around (possibly one-handed) or, where applicable, wear on their body (e.g. via a harness).

The device may be considered to be an air processing unit. The device may be part of a personal air purification system, particularly a two-part personal air purification system.

The system may include a face mask which can be connected to the device, e.g. via a feed line or tube, to receive filtered or purified air from the air outlet of the device. This allows a steady flow of filtered air to be provided to the nasal-oral area of the mask wearer's face The air filtering device can supply filtered air under positive pressure to the face mask. This minimises build-up of moisture in the mask during use, which helps to avoid 'fogging' of reading glasses when the user exhales. The positive air pressure also negates the amount of exhaled air which is breathed in when the user inhales.

Providing a two-part system decouples the filtration portion (the air filtering device) from the breathing portion (the face mask). For example, the impeller or fan, and the air filter may be disposed in the air filtering device instead of the face mask. Similarly, a power source, such as a battery, and any control electronics may be disposed in the device instead of the mask.

This minimises the bulk and/or weight of the face mask, which makes it easier to wear for any period of time. This can make it easier to perform exercise whilst wearing the mask. It also means that the filtration portion can be substantially larger than if incorporated into the body of the face mask, which may increase the lifetime and/or filtration capacity of the air filtering unit. For example, a comparatively larger power source may be provided to increase available operating time, and/or a comparatively larger filter element may be provided to increase the filtering capacity and lifetime of the air filter.

In some embodiments, the device may be worn on or strapped to the person's body, and the rotatable head can freely move or self-adjust as the person moves or walks. This avoids inhibiting their movement, such as during walking if the feed line extends across their torso.

In some embodiments, the device may be used at a desk, for example, without needing to wear or even have a face mask for the device. The rotatable head portion may be oriented such that the direct air outlet is directed towards the person, for supplying air towards the person.

In some embodiments, the device may be used in a car or other vehicle, or another enclosed space, again without necessarily having or using a face mask for the device. This can remove contaminants which are not removed by an air-conditioning system. The device may fit in a drink vessel holder or another holder in a vehicle, for example.

The rotatability of the head means that the air outlet can be easily directed towards a person in either front seat or seats behind the front seats of the vehicle.

The air outlet and/or head portion may be moveable or pivotable between first and second positions. In the first position, the air outlet may direct filtered air substantially longitudinally out of the device (or in a direction which is substantially parallel to the longitudinal axis of the device). In the second position, the air outlet may direct filtered air laterally out of the device (or in a direction which is substantially perpendicular to the longitudinal axis of the device).

The air outlet and/or head portion may be moveable or pivotable to one or more intermediate positions between the first and second positions for directing filtered air out of the device at an angle, relative to the longitudinal axis of the device.

This allows the elevation angle of the air outlet to be varied relative to the head portion. For example, the air outlet may be set at an elevation angle from around zero degrees to 90 degrees, although it will be appreciated that the angle may be greater than 90 agrees and in some embodiments up to around 180 degrees.

In conjunction with the 360 degree rotatability of the head portion or air outlet, air flow may be directed in substantially any direction away from the device. That is, the polar angle 0 and the azimuthal angle cp of the air outlet can be adjusted as needed to provide a directional flow of filtered air to the person using the device.

The air outlet may be interpreted as the aperture through which filtered air exits the device. The air outlet may be interpreted as the structure which contains the aperture through which filtered air exits the device The air outlet may be a nozzle. The air outlet or nozzle may include an elongate conduit. This can provide a focussed flow of filtered air towards a person's face when the device is on its own. The nozzle also provides a connection for an air feed line or conduit for supplying air to a face mask.

The air outlet or nozzle may include a curved wall. The curved wall may be disposed within the head portion of the device. The curved wall may help direct or re-direct filtered air out of the nozzle. This may depend on the elevation angle of the air outlet or nozzle relative to the device. A corresponding curved wall may be provided as part of the head portion for the curved wall of the air outlet to rotate against (or adjacent to).

The air outlet or nozzle may have a second curved wall, opposite the first curved wall.

A corresponding second curved wall may be provided as part of the head portion for the second curved wall of the air outlet to rotate against (or adjacent to).

The head portion of the housing may include a recessed section for accommodating the air outlet or nozzle. This can allow the air outlet to be in a lateral position where a surface of the outlet is substantially flush with the top of the head portion.

The nozzle may be integrally formed with the head portion of the housing. This can be useful where the device is intended for use in a fixed position or predetermined arrangement, for example on top of a cot or at the side of a pushchair.

The air filter may comprise a two-stage cartridge filter. The air filter may comprise a HEPA filter and/or a carbon filter. The carbon filter may comprise activated carbon, for example in a layer or in the form of granules (or a layer of granules).

The air filter may be releasably secured within the housing. This makes it easy to remove the filter for cleaning or replacement. For example, the user may elect to wash the existing HEPA filter rather than replace it with a brand new HEPA filter.

Air from the air inlet may pass through either or preferably both the HEPA filter and carbon filter before reaching the air outlet. Preferably air passes first through the HEPA filter followed by the carbon filter.

The HEPA filter is intended to remove aerosols and biological contaminants -such as bacteria, viruses and pollen -in the air passing through the filter. The HEPA filter can also remove dust and other particulate matter. The HEPA filter has a significantly higher surface area than would otherwise be practical for a face mask. This is possible by virtue of the two-part or segregated nature of the air filtering components and the face mask.

The carbon filter is intended to remove or neutralise gaseous contaminants/pollutants such as CO, NO and VOCs in air passing through the filter. The carbon filter has a significantly higher volume of activated carbon than would otherwise be practical for a face mask, increasing the filter capacity to neutralise or remove gaseous contaminants.

Again, this is made possible by virtue of the two-part or segregated nature of the air filtering components and the face mask.

The surface area of the HEPA filter and/or the volume of active carbon provided in the device may be sufficient to provide air filtration which substantially matches, in terms of filtered air quality, that of a non-portable indoor air purification system (such as a floor-standing air purifier).

The air filter may comprise a C-shaped cartridge. That is, a cartridge with a C-shaped cross-section. This is suitable for fitting within the housing whilst providing room for the impeller and other components, e.g. battery.

The air filter may comprise a cylindrical filter. This may be referred to as a 'closed' filter.

The air inlet may include a plurality of apertures or perforations. The apertures may be provided through the body portion or side of the housing. This minimises any draft from air being drawn through the inlet, and also means that the device can still operate relatively well if some of the air inlets are inadvertently blocked or covered.

A digital display may be provided along a side of the housing for displaying information about inlet and/or outlet air quality.

Having a display or readout makes it easy to see at a glance whether air quality is at an acceptable level. For example, a parent or carer can quickly check whether air in the vicinity of a baby or young child meets acceptable air quality levels. If not, they may activate the device if it is not yet active.

The display or readout may relate to air quality of unfiltered air in the vicinity of the device. The display or readout may relate to air quality of the filtered air exiting the air outlet. The display or readout may relate to be unfiltered and filtered air qualities. Other parameters such as battery charge level, projected remaining air filter usage and so on may be available via the display.

The device may comprise a wireless transmitter for sending data to a remote electronic device. Data related to air quality and/or other parameters may be transmitted (whether automatically, periodically or on demand) to a smartphone or other electronic device for any one or more of storage, display and/or relay to a central data store.

The device may be able to activate automatically according to one or more air quality parameters, optionally by setting or configuring the threshold for the/each parameter (although the activation threshold(s) may be pre-configured in the device). A deactivation threshold may also be set or pre-configured.

A battery compartment may be provided in the housing for receiving a battery to power the motor and impeller. The battery compartment may be adapted to receive a single battery. The battery compartment may be adapted to fit a cylindrical battery.

The device may be powered by a lithium ion battery. The battery may be rechargeable.

The device may continue to operate whilst charging, if the device is switched on.

The charge capacity of the battery may be at least 2000 mAh. Preferably the capacity is at least 2300 mAh, and more preferably at least 3000 mAh.

The battery capacity is selected such that the device can operate continuously or periodically for at least 2 hours to provide filtered air to a person. Preferably the battery may have a capacity sufficient for the device to operate for at least 3 or 4 hours, or more preferably at least 8 hours, from a full state of charge.

The device may have a recharging port connected to the battery compartment or battery. The port may be a USB or micro-USB port, although other suitable types of port are contemplated as far as they would be suitable for recharging a battery.

The impeller may be substantially conical. The impeller may be wholly or partially disposed in the body portion of the housing. The wider portion of the conical impeller may face towards the head portion of the housing.

The impeller may have a plurality of vanes for forcing the filtered air outwards from a central longitudinal axis of the impeller and towards the air outlet.

The motor may be a brushless motor, preferably a brushless DC motor.

The housing may include a substantially cylindrical outer surface which is sized to fit in one hand. That is, the diameter of the cylindrical housing may be approximately the same as that of a conventional carbonated drink can.

The body portion of the housing may comprise a bracket or one or more mounting points for mounting the device to at least one of: a wearable harness, a cot and a pushchair.

A harness may be provided with mounting points for the air filtering device. The harness may have a quick release bracket for the air filtering device, or a complementary connection for a bracket of the air filtering device.

The harness may have a strap suitable for wearing over the shoulder or across the torso. The strap may be adjustable for use in either scenario.

A control button may be provided on the housing. The control button may be used to activate and/or deactivate air filtering or the device as a whole. The button may be used to control the air filtering mode of the device.

For example, the button may allow the user to switch between different air flow rates (such as preset low and high air flow rates, and optionally an intermediate or medium flow rate). The button can be pressed and held for a short time, such as one second or half a second, to cycle through the options (off, low, high) in some embodiments. It will be appreciated that any number of modes may be provided, in addition to an 'off' state.

The base of the housing may be removable. This can allow access for removing the air filter or changing the battery, for example.

The device may have a recess for inserting a fragrant element or fragrance container. For example, a fragrance stick or liquid fragrance may be provided. The fragrance may be introduced into the filtered air prior to exiting the air outlet or nozzle, for example.

However, this is not essential, and the fragrance may arranged to diffuse ambiently into the filtered air flow, for example.

The device may have a compartment or connection for an inhalable medicine or container therefor. The medicine may be dispensed on demand (e.g. pressing a button or switch, or moving a medicine container), for example. The medicine may be introduced into the filtered air prior to exiting the air outlet or nozzle. This is generally only preferred when a face mask is connected to the device and being worn.

The air outlet may be connected to an elongate tube or conduit. The elongate tube or conduit may be connected to a face mask for supplying filtered air into the face mask (such as a face mask according to the second aspect of the invention). The air outlet to elongate conduit connection may be releasable. The elongate conduit to face mask connection may be releasable.

The device may be mounted to a cot or a pushchair for directing filtered air towards the occupant of the cot or pushchair. The air outlet may be oriented towards and/or extend into an internal region thereof (or may be adjusted to achieve the same).

The term cot is intended to mean a bed intended for use by a baby or young child. The term pushchair is intended to mean a carriage in which a baby or young child lies/sits and can be moved, such as a pram, buggy or stroller.

It will be appreciated that the 360 degree rotation of the head portion or air outlet is not essential where the device is mounted to a cot/pushchair. For example, the device may have the bracket in a custom position corresponding to the particular cot or pushchair to ensure it directs filtered air to the correct region, i.e. towards the baby of child. The bracket may be adjustable on or relative to the housing to ensure the air outlet is oriented appropriately. Of course, in some embodiments the air outlet and/or head portion may be rotatable, preferably through 360 degrees.

According to a second aspect of the invention, there is provided an air filtering device for mounting to a cot or pushchair for directing filtered air to the occupant, the device comprising a housing including a body portion and a head portion (or top cap) which is connected to the body portion, an air inlet for air to enter the housing, an air filter within the body portion for filtering air received from the air inlet, an impeller in the housing for conveying or drawing air through the air inlet and air filter, and a motor for powering the impeller, and an air outlet at a distal end (or top) of the head portion of the housing for receiving filtered air under positive pressure from the impeller.

The invention aims to provide localised protection for an infant in a cot or pushchair by providing a stream or flow of filtered air towards the infant, which maintains higher air quality around the infant. The device may still be small enough to be portable.

The device is a high-performance portable air purifier which in use removes airborne pollutants from the local vicinity of a child's cot and/or pushchair to provide protection for infants. The advantages are similar to the first aspect of the invention, particularly addressing air pollution within a home or other domestic environment by removing particulate matter and VOCs, amongst others.

The head portion may taper or narrow with increasing distance from the body portion. The head portion may taper or narrow from the body portion to the air outlet. That is, the space or conduit within the head portion for filtered air leaving the impeller becomes narrower towards the air outlet. This can help to focus the stream of filtered air during use.

The tapering/narrowing may be in one dimension. For example, a first width of the head portion may remain substantially unchanged whilst a second width of the head portion reduces towards the air outlet. The first and/or second widths may be measured perpendicular to a longitudinal axis of the device.

The device may be connected to a cover (preferably an adjustable cover) positioned over the infant's cot, such that a stream of filtered air is delivered across the child.

The cover may be provided for creating an enclosed space to better retain an amount of filtered air in the vicinity of the infant or child in the cot/pushchair.

The head portion may be rotatable (preferably through at least 90 or 180 degrees, more preferably 360 degrees) relative to the body portion for directional flow of the filtered air during use.

The air outlet may be rotatable (preferably through at least 90 or 180 degrees, more preferably 360 degrees) relative to the head portion for directional flow of the filtered air during use.

A bracket may be provided on the housing for mounting the device to the cot/carriage.

A corresponding mount or bracket connector may be provided on the cot/carriage or a cover or other part thereof. The mount or connector should be in a position adjacent to the seat or bed of the cot/carriage.

The bracket may be adjustable on or relative to the body for adjusting the orientation of the outlet relative to a mounting for the bracket, e.g. cot or pushchair.

The bracket may be on the same side of the device as the air outlet.

The cot/carriage may include a holder for the device. When the device is in the holder, the air outlet should be directed towards or into the space around the occupant(s) (or where the occupant(s) would normally sit or lie).

The air outlet may be in a fixed position relative to the housing, or its position may be adjustable. If fixed, the air outlet may direct air substantially perpendicularly away from a longitudinal axis of the device. If adjustable, the air outlet may be positionable to direct air in the same way.

The air outlet may be a slot.

Any other feature presented with respect to the first aspect of the invention may be independently provided as part of the second aspect of the invention.

According to a third aspect of the invention, there is provided a face mask for breathing filtered air, the face mask comprising an inner member including a breathing portion for fitting over at least a person's mouth and/or nose, an outer covering over the inner member, a first port at a first side of the face mask for receiving filtered air under positive pressure from a portable air filtering device, and air flow channelling in the mask including: a first main air flow channel connected to the first port, and a first plurality of secondary air flow channels which are connected to the first main channel and arranged across the breathing portion for distributing filtered air across the breathing portion during use.

Providing a face mask with different inner and outer parts (that is, a two-part face mask) enables air flow through the mask to be controlled more effectively. The mask is intended for use with a personal air filtering device, so that ambient unfiltered air is not breathed in whilst the mask is being worn (and supplied with filtered air). This is particularly useful with regard to public transport, for example, where many people may be in close quarters and it is possible for airborne contagions to spread more easily. However, it is also suitable for use in other public places including buildings or outdoor venues, for example.

The face mask has novel air flow channelling which, when supplied with filtered air under positive pressure via the air inlet port, provides even distribution of filtered air across the breathing portion. This makes it comfortable for a person wearing the mask to breathe normally. The wearer is typically unaware of the direction of the air flow. That is, during use the air flow can feel like a directionless breeze as opposed to feeling like a draught from left/right to right/left across their face.

On some occasions during use, when an air filtering device is connected to the mask, the air flow rate from that device may on its own be insufficient to match the amount of air required when the wearer breathes in. If this happens, the vacuum generated by virtue of the person breathing in helps to draw air through the air filter in the air filtering device.

The term face mask is intended to mean a mask which covers at least the nose and mouth of a person, when the mask is worn. The mask may extend over the sides of the person's face, towards the ears.

The term breathing portion is intended to mean the part(s) or region(s) of the mask through which air is inhaled and/or exhaled during use.

Optional features of the face mask are set out in claims 17 to 24.

The air flow channelling may be provided by at least the inner member. The air flow channelling may be provided between the inner and outer members.

The inner member may be rigid, or at least sufficiently rigid to substantially maintain its shape. This helps mitigate collapse or deformation of the inner member, which would affect air flow in the mask.

The inner member is preferably sized to fit over the wearer's nose and mouth. The inner member may include a rigid oral-nasal inner section.

A second port may be provided at a second side of the face mask. The air flow channelling may include a second main channel connected to the second port. The air flow channelling may include a second plurality of secondary channels. The second plurality of secondary channels may be connected to the second main channel. The second plurality of secondary channels may be arranged across the breathing portion.

This allows the first set of channels to be used for inbound air for inhalation, and the second set of channels can be used for outbound air from exhalation.

The first and second ports may be interchangeably configurable as an air inlet port and an air outlet port respectively. The ports may therefore be considered as universal ports for receiving either of an air feed line and an air filter. The user can therefore connect an air feed line to either the left-hand or right-hand side.

The first and second pluralities of secondary channels may be provided in an interdigitating arrangement. The first set of channels may be air inlet channels and the second set of channels may be air outlet channels.

The inner member or breathing portion may include a zigzag arrangement or lattice structure for separating the inlet channels from the outlet channels. This can provide an alternating arrangement of inlet and outlet flow channels. The inlet and outlet channels may alternate in an AB arrangement (ABABAB(A)...), although other arrangements may be provided.

By providing the flow channels in an interdigitating or alternating arrangement, air pressure is substantially equalised across the breathing portion. It also helps to exhaust exhaled air from the mask, which in turn substantially prevents or minimises fogging of glasses when worn with the mask.

The second port includes a one-way valve which is configured to close during inhalation and open during exhalation. The one-way valve may include an air filter (preferably a HEPA filter) for filtering exhaled air. The air filter may be in the form of a disc for insertion into or over the air outlet port. The air filter may be removable.

Wien a wearer is not breathing in, air supplied into the mask is able to exit through the one-way release valve on the mask. When the wearer breathes in, the valve closes and so only filtered air supplied via the air inlet (which is connected to an air filtering device during use) can be inhaled.

Wien the wearer breathers out, the exhaled air passes through the air filter to prevent aerosols being exhausted to the surrounding environment. In the event that the mask wearer has a contagious illness which can be spread via small airborne droplets in the air they breathe out, this can substantially mitigate the risk of transmitting the illness to another person.

A plurality of slots may be provided in the breathing portion. The slots may be spaced apart. The slots may form a grille. The slots may be arranged laterally across the breathing portion. At least some of the slots may be aligned with corresponding channels of the first plurality of secondary channels. Some slots may be aligned with corresponding channels of the second plurality of secondary channels.

A seal may be provided on the inner member for sealing against a person's face. Preferably the seal is flexible. The seal may be made of silicone.

The seal provides an airtight connection to the person's face to prevent unfiltered air entering the mask. The seal may be made of any suitable material for providing an air tight seal on a person's face. Ideally, the material is comfortable and does not cause excessive perspiration (or may wick perspiration away to at least some extent).

The outer covering may be a fabric member comprising means for securing the face mask to a person's head. The outer fabric may provide enhanced aesthetics as well as means to affix the inner mask to a person's head.

According to a fourth aspect of the invention, there is provided a kit comprising a portable air filtering device according to the first aspect of the invention, and a face mask according to the second aspect of the invention. Optionally, an elongate conduit is provided for connecting the face mask to the portable air filtering device.

The elongate conduit (or air feed line) may comprise flexible tubing that can be connected to and disconnected from the face mask and air filtering device. The tubing may have an airtight seal to both the face mask and the air filtering device when connected between them.

The conduit may be flexible. The conduit may be made of a silicone or a plastic such 15 as PVC.

Magnetic connectors may be used to secure the conduit to the air outlet of the air filtering device, and to the inlet port of the face mask.

This provides a robust means of locating and holding the air feed line in the correct location. However, should the line accidentally become snagged or pulled, the air feed line will rapidly disconnect and thus not potentially endanger or injure the wearer.

Any feature or features presented with respect to one aspect of the invention may be independently provided in any other aspect of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made by way of example only to the accompanying drawings, in which: Figure 1 shows a front perspective view of a portable air filtering device; Figure 2 shows rear perspective view of the device of Figure 1; Figure 3 shows a cross-sectional perspective view of the device of Figure 1; Figure 4 shows a perspective view of a bracket connectable to the device of Figure 1; Figure 5 shows a perspective view of the device of Figure 1 connected to a face mask by an air feed line, where the face mask is not to scale relative to the portable air filtering device; Figure 6 shows a perspective view of the face mask shown in Figure 5; Figure 7 shows a left-side perspective view of the face mask of Figure 6; Figure 8 shows a right-side perspective view of the face mask of Figure 6; Figure 9A shows a rear view of a rigid inner member of the face mask of Figure 6, indicating air flow when filtered air is supplied via the right side port; Figure 9B shows a rear view of the rigid inner member of the face mask of Figure 9A, indicating air flow when filtered air is supplied via the left side port; Figure 10 shows a rear perspective view of a second embodiment of a face mask; Figure 11 shows a rear view of a third embodiment of a face mask; Figure 12 shows a front view of a person wearing a face mask which is connected to a portable air filtering device, which is mounted on a harness or strap; Figure 13 shows a perspective view of a second embodiment of an air filtering device on a cot; Figure 14 shows a second, enlarged perspective view of the device of Figure 13; Figure 15 shows a perspective view of a third embodiment of an air filtering device on a pushchair; and Figure 16 shows a second, enlarged perspective view of the device of Figure 15. DESCRIPTION OF PREFERRED EMBODIMENTS Figures 1 to 3 show an air filtering device 10 for providing filtered (or purified air) to a person. The device 10 can be used in a variety of locations, including but not limited to: on a desk; in a vehicle; or when carried or worn on the body On conjunction with a corresponding face mask, discussed further below). That is to say, the device 10 is small enough to be easily portable.

The device 10 has a substantially cylindrical body or housing, although it is contemplated that other shapes may be used in related embodiments. The device 10 includes a body portion 12 and a head portion 14 connected to an end of the body portion 12. The body and head portions are together considered to provide the housing. A removable base 12a is provided the bottom end of the body portion 12. The body portion 12 is cylindrical. The head portion 14 is frustoconical. The removable base 12a is frustoconical.

A peripheral edge or circumference of the head portion 14 is rounded or chamfered. A peripheral edge or circumference of the base 12a is rounded or chamfered.

The head portion 14 is rotatably connected to the body portion 14 about a central longitudinal axis of the body portion 12 in this embodiment. The central longitudinal axis of the body portion is also a common longitudinal axis of both portions 12, 14. The head portion 14 is freely rotatable through 360 degrees in either direction (clockwise or anticlockwise) in this embodiment.

An air inlet is indicated generally at 16, the air inlet being provided in the side of the body portion 12. In this embodiment, the air inlet comprises a plurality of inlet apertures or perforations which are distributed around the curved side of the body portion 12. During use, this allows the device 10 to draw air in from substantially around its full perimeter or circumference.

An air outlet 18 is provided in a top end of the head portion 12. The air outlet 18 may be considered to be a nozzle. The air outlet 18 has an open end 18a for exhausting filtered air from the device 10. When the head portion 14 is rotated, the air outlet 18 rotates with the head portion 14 about the longitudinal axis of the device 10.

The air outlet 18 is pivotally connected to the head portion 14. That is, the elevation angle of the air outlet 18 is adjustable so that filtered air can be directed away from the device 10 in different directions. In this embodiment, the elevation angle of the air outlet is adjustable through substantially 90 degrees. The air outlet 18 is maintained at the desired elevation angle once set (e.g. by means of the pivot mechanism in some embodiments).

In Figure 1, the air outlet 18 is shown in a lateral position, for directing air laterally away from the device 10. The top surface of the air outlet 18 (as viewed) is substantially flush or co-planar with the top surface of the head portion 14.

Figure 2 shows the air outlet 18 in another position, angled at approximately 60 degrees away from the longitudinal axis of the body portion 12. A recess 14a is provided in the head portion 14 to accommodate the air outlet 18. The recess 14a is shaped to substantially match to the air outlet 18.

It will be appreciated that the air outlet 18 can also be moved or pivoted further such that it is substantially coaxial with the longitudinal axis of the device 10. Similarly, it will be appreciated that the air outlet is freely adjustable from the lateral position (Figure 1) to a substantially upright position to provide control over the direction of filtered air flow.

A control button 20 is provided on a side of the device 10, in this case on the body portion 12. The button 20 is disposed about halfway along the side of the device 10.

The control button 20 is a power button to control activation and deactivation of the device 10. That is, it is an on/off switch. When the device is off, pressing and holding the control button 20 for a short period of time (e.g. 1 second) turns the device 10 on.

The control button 20 can also be used to control the flow rate or speed at which filtered air exits the air outlet 18. When the device 10 is on, the initial flow rate may be a 'high' flow rate. Pressing and holding the control button 20 for a short period of time (e.g. 0.5 seconds) changes the operational mode to provide a filtered air flow rate which corresponds to 'medium' flow. With the device in that state, pressing and holding the control button 20 for a short period of time (e.g. 0.5 seconds) changes the operational mode to provide a filtered air flow rate which corresponds to a low' flow rate. Repeating this again will turn the device off.

It will be appreciated that the device may only have one or two air flow rates, or may have more than three flow rate options, and that the period of time the button may be pressed can vary. Similarly, the button 20 may be pressed in a sequence of presses to control device mode or state.

In other embodiments, there may be additional controls to control device operation, instead of a single button 20.

A battery charging port 22 is provided in a side of the device 10, in this case on the body portion 12. The port 22 is provided in-line with the control button 20 on the side of the device 10. In this embodiment, the port 22 is provided substantially adjacent to the base 12a. In this embodiment, the port 22 is a micro-USB port.

A bracket 24 is provided on a side of the body portion 12. The structure of the bracket is shown more clearly in Figure 4. The bracket 24 includes a latch 24a at one end. The latch has a detent for securely connecting to the device 10. The latch 24a also has a protrusion 24aa for manually releasing the latch from engagement with the device 10.

A pair of hooked arms 24b are provided at the other end of the bracket 24 for hooking into the slot on the body portion 12. A plate or planar body 24c forms the main body of the bracket 24. The hooked arms 24b are connected to the plate 24c. The latch 24a is integrally formed in the plate 24c. Flanking elements 24d are provided to either side of the latch for strengthening the latch connection.

The hooked arm portion includes a concave or curved section 24e between the hooked arms 24b for conforming to the curved side of the body portion 12.

The latch portion includes a pair of concave or curved sections 24f, spaced apart to either side of the latch 24a, for each conforming to the curved side of the body portion 12. In this embodiment, the curved sections 24f are part of the latch flanking elements 24d.

In Figures 1 and 2, the bracket 24 extends into a slot 12b in the body portion 12. In this embodiment, the bracket is rotationally offset from the button 20 and port 22 by 90 degrees, relative to the angular position around the central longitudinal axis of the device 10.

The bracket 24 includes a latch 24a which releasably secures the bracket 24 to the body portion 12 or the base 12a thereof. The bracket 24 is preferably used when the device 10 is worn on a harness on a person's body, but can be removed for other use cases if so desired.

Figure 3 shows internal parts of the device 10. A portable power source in the form of a battery 26 is provided in a battery compartment 28 in the body portion 12. The battery 26 is disposed on the central longitudinal axis of the body portion 12. In this embodiment, the battery is an 18650 Li-ion battery.

An air filter 30 is disposed in the body portion 12. The air filter 30 comprises a HEPA filter and an activated carbon filter. The air filter 30 is arranged to receive air from the plurality of air inlets 16. In use, air passes sequentially through the HEPA and carbon filters. In this embodiment, two C-shaped air filter cartridges are provided. The cartridges are removable for cleaning or replacement when necessary.

A chamber or flow conduit 32 is provided in the body portion 12 for receiving filtered air from the air filter 30. The chamber 32 may be shaped as a substantially cylindrical shell around the battery compartment 28.

A fan is provided at an upper end of the body portion 12, adjacent to the head portion 14. The fan includes a motor 34 and an impeller 36 which is driven by the motor 34. A plurality of vanes 36a are provided in the impeller.

The motor 34 is a brushless DC motor, and is powered by the battery 26. Suitable electrical connections are provided to supply electricity from the battery to the motor.

The impeller 36 has a substantially frustoconical conical shape. The exterior of the frustum cone is a concave surface. The impeller 36 widens with decreasing distance towards the head portion 14.

An air flow path from the air filter 30 to the impeller 36 is provided by the chamber 32. During device operation, filtered air is drawn through the filter 30 and chamber 32, and forced through the impeller 36 by virtue of the powered rotation of the impeller 36.

A second chamber or conduit, indicated generally at 38, is provided in the head portion 14 at an upper end of the impeller 36 for receiving air from the impeller 36. A first portion of the chamber 38 is shaped substantially like a cylindrical shell. A second portion of the chamber 38 extends substantially horizontally under the top of the head portion 14, for feeding air to and through the air outlet 18.

Another chamber or space, indicated generally at 40, is provided centrally above the impeller 36, within the head portion. This chamber 40 is separated from the second chamber 38 by a dividing wall 42.

The structure of the air outlet 18 is shown in detail in Figure 3. The air outlet 18 includes an elongate conduit or nozzle 18b. The conduit 18b is hollow.

A first curved wall 18c is connected to a lower side of the conduit 18b. That is, the side nearer to the body portion 12. The first curved wall 18c extends through approximately 90 degrees, as seen in the cross-section in Figure 3.

A correspondingly curved wall 42c is provided as part of the dividing wall 42, adjacent to the first curved wall 18c. The curved wall 42c is located on the central longitudinal axis of the device 10 A second curved wall 18d is connected to an upper side of the conduit 18b. That is, the side nearer to the top of the head portion 14. The second curved wall 18d is smaller than the first curved wall 18c.

The curved walls allow for rotation or pivoting of the air outlet whilst maintaining the air flow path. During use, air flow passes from the second chamber 38 and through the space between the curved walls 18c, 18d, and out through the conduit 18b of the air outlet.

To use the device on a desk or in a vehicle, the device 10 is placed on the desk or in a cup holder, for example. The head portion 14 can be rotated relative to the body portion 12 to align the air outlet 18 in the user's direction. The elevation of the air outlet can be set by pivoting the air outlet 18 to aim it towards the user's face. With the device 10 switched on, a flow of filtered air is directed in the user's direction, providing a localised supply of filtered air for breathing.

Figure 5 illustrates a personal filtered air supply system which includes the device 10.

One end of an air feed line 50 is connected to the air outlet 18. Another end of the air feed line is connected to a face mask, indicated generally at 100. Features of the face mask is discussed in more detail with respect to Figures 6 to 11.

The conduit 50 is a hollow tube. The internal diameter of the conduit in this embodiment is 10mm. However, it will be appreciated that the tube may be of any diameter or length, subject to the dimensions being suitable for the air filtering device 10 to force air through the conduit 50 to the mask 100.

By forcing the air through the conduit 50 and into the face mask 100, the filtered air is supplied to the wearer of the face mask to the exclusion of unfiltered air. That is, they do not breathe air directly from the atmosphere around them without it first having been filtered through the device 10. This is particularly useful when the person wearing the mask is in a crowded space with other people, because a) it significantly reduces the likelihood of contracting an illness via airborne transmission (if someone near the wearer is ill), and b) it significantly reduces the likelihood of transmitting an illness via airborne transmission Cif the wearer is ill).

It should be noted that the device 10, conduit 50 and face mask 100 are not necessarily shown to scale relative to each other in Figure 5. A more representative arrangement is shown in Figure 12, discussed below.

Figures 6 to 9B show a first embodiment of a face mask 100. The face mask includes a fabric outer member or covering 102 and a rigid inner member 104. The outer fabric is preferably substantially air-impermeable.

The inner member 104 may be considered to be a nasal-oral section. That is, it is sized and shaped to fit over the wearer's nose and mouth. The outer covering 102 is shaped to fit over the inner member 104. The outer covering 102 is shaped substantially similarly to the general shape of a person's face (including the cheeks, nasal-oral region, and chin). In this embodiment, upper edges of the mask include concave curves. This can make the mask more comfortable to wear.

First and second air flow ports 106, 108 are provided on left-hand and right-hand sides of the mask 100 respectively. The ports 106, 108 are disclosed close to the wearer's ears, at the side of the head. The ports 106, 108 are structurally substantially identical. Either one of the ports can function as an air inlet, and the remaining port can function as an air outlet. That is, the ports 106, 108 are interchangeable.

The air inlet port 106 is adapted for connection to an air feed line, such as line 50 from Figure 5. The air outlet port 108 has a one-way valve (not shown) which allows exhaled air to exit the mask during exhalation, but closes during inhalation. It will be appreciated that the inlet port 106 also has a one-way valve (not shown) in order for either port 106, 108 to be used as the outlet, but that it remains open during use due to positive air pressure from an air filtering device 10 (see Figure 5).

The rigid inner member 104 includes a breathing portion. This is provided by a plurality of lateral elements 110. The lateral elements 110 are spaced apart to provide space for air to flow for breathing. The lateral elements 110 run substantially parallel to each other. The lateral slots between the elements 110 run in the general direction of inbound air flow from the air inlet port.

It will be appreciated that the elements need not necessarily be lateral, and slanted or vertical elements (and corresponding slots) may be provided in some embodiments. It may be the case the elements and/slots are not provided, and a mesh or series of apertures may be provided instead. Any suitable space(s) for receiving inbound air flow and allowing passage of exhaled air may be provided to allow the breathing portion to achieve its intended function.

Air flow channelling is provided in the form of a 'zigzag' arrangement or structure, indicated generally at 112 in Figures 9A and 9B, in the mask 100. This defines two sets of air flow paths or channels within the mask 100. That is, there is a structure within the mask 100 which provides a first plurality of channels for inbound air flow for inhalation, and a second plurality of channels for outbound air flow from exhalation. The zigzag arrangement may be considered as interdigitated air flow channels.

In this embodiment, the zigzag structure is substantially aligned with the slots or lateral elements 110 in the inner member. It will be appreciated that in some embodiments the lateral elements 110 may be structured and connected together in a way that provides some or all of the zigzag structure 112 in the mask 100.

Figure 9A depicts air flow through the mask 100 when port 108 is used as an air inlet port for filtered air from an air filtering device (such as device 10). Inbound air flow is channelled through the port 108 in a direction which is initially in a direction approximately parallel to the sagittal plane (that is, travelling from back to front relative to the mask wearer). The air flow is then directed through a main channel or similar round the wearer's face into a direction which is approximately parallel to the coronal place (that is, travelling across the mask wearer, from right/left to left/right, depending on which port is used as the air inlet).

As part of the re-direction process, the inbound air flow is split between and passes along about half of the air flow channels in the mask 100. The inbound air flow is indicated by arrows A, which show that the air flow passes substantially across the slots for providing a relatively even distribution of filtered air for breathing in.

In some embodiments, the inbound air flow may be provided conditioned on passing through the port to split the flow into multiple streams, but this is optional.

Exhaled air flow is indicated by arrows B, for when the mask wearer breathes out. The exhaled air may pass primarily through a centre region of the breathing portion, but the extent of the arrows B across the mask 100 is not intended to imply any limitation about where the flow of exhaled air can pass between the lateral elements 110. The exhaled air passes to air outlet port 108 for venting.

Figure 9B depicts air flow through the mask 100 when port 106 is used as an air inlet port for filtered air from an air filtering device (such as device 10), and port 108 is used as an air outlet port. The mask 100 functions in the same way as detailed above, with inbound air indicated by arrows A' and outbound air indicated by arrows B'.

Optionally, an air filter (such as a HEPA filter, not shown) can be inserted into or over the port 108 for filtering exhaled air. The filter may be disc-shaped. Each port 106, 108 may include a filter recess or filter connection for the air filter.

Figure 10 shows a second embodiment of a face mask, indicated generally at 200. The face mask 200 is substantially similar to the mask 100, except as now described. Like reference numerals are used to indicate like features, where possible.

The air outlet port 206 on the mask has a series of channels 206a. The channels 206a help to protect the HEPA filter (e.g. disc) which connects in or to the port 206.

An air inlet connector 220 is attached to the other port (not visible). In this embodiment, the connector 220 is removable for connection to either port. The connector 220 is configured to connect an air feed pipe from an air filtering device.

Figure 11 shows a third embodiment of a face mask, indicated generally at 300. The face mask 300 is substantially similar to the mask 100, except as now described. Like reference numerals are used to indicate like features, where possible.

In this embodiment, the mask 300 two possible air inlet ports 306a, 306b. One or both of the ports 306ab may be used for inbound air under positive pressure.

The mask 300 also has two possible air outlet ports 308a, 308b. This provides the option to have two stale/exhaust air filters (e.g. HEPA filters), one in each port.

The rigid inner member 304 has lateral elements 310 and slots. Rather than extending across the full width of the mask 300, there are discrete left-and right-hand sets of elements 310a, 310b with a central vertical slot 310c between them. Some of the left-hand slots can vent exhaled air through the left-hand outlet port 308a. Some of the right-hand slots can vent exhaled air through the right-hand outlet port 308b.

A flexible seal 314 is provided for providing a substantially airtight seal against the user's face. The seal 314 is made of silicone in this embodiment. Providing a flexible seal makes the mask 300 more comfortable to wear, and ensures that unfiltered air is substantially prevented from entering the mask 300. The airtight seal may form a perimeter around the wearer's nasal-oral region during use.

It will be appreciated that a flexible seal may be provided in any embodiment of the 30 face mask Figure 12 shows a further embodiment of a face mask connected to an air filtering device by a conduit, indicated generally at 400. A harness or strap 402 is also worn by the person depicted. The air filtering device 10 has been mounted to a corresponding portion of the harness 402 via the bracket 24.

In this embodiment, the conduit 50 is held against the strap 402 by a clip or other retaining device 404. This generally keeps the conduit from flapping loose and potentially catching on things as the user moves about.

Figures 13 and 14 show a second embodiment of an air filtering device 500 for use on a cot 502 or similar. The device 500 has similar features to the device 10 of the first embodiment, except as now described. Like reference numerals are used to indicate like features, where possible.

The device 500 is mounted or clipped to a cover 504 (which may be transparent, as shown) over the cot 502. The cover 504 should have an aperture therethrough to allow filtered air flow from the device to pass into the interior area of the cot where an infant may lie. The device is oriented horizontally in this embodiment and directs airflow downwards into the cot.

The device 500 has a head portion 514 which has an integrally formed air outlet 518. The air outlet 518 is a slot at its open end in this embodiment. The head portion 518 is integrally formed with the body portion 512 in this embodiment, although it is contemplated that variations of this embodiment may include a head portion which is rotatable relative to the body portion).

The head portion 514 and air outlet 518 is curved such that air exiting the impeller in a longitudinal direction (relative to the longitudinal axis of the device) is directed to exit the outlet in a substantially lateral direction. That is, it exits in a direction substantially perpendicular to the longitudinal axis of the device 500.

The device 500 has a bracket 524 for connection to the cover 504.

A digital display 544 is provided along the side of the device 500. The display 544 can show information relating to various metrics for inbound and/or outbound air quality, such as relative levels of various contaminants (e.g. total VOCs, particulate matter).

Like the first embodiment describing the air filtering device 10, the device 500 is intended to remove particulates (down to about 2.5 micrometres in size) along with certain reactive gases (VOCs) including CO, SO x and NO", amongst others.

One or more sensors for detecting one or more contaminants may be provided to achieve this. Inbound airflow sensor(s) may detect contaminants in air prior to passing through the air filter. Outbound airflow sensor(s) may detect contaminants remaining in the air after it has passed through the air filter. One or more sensors may be provided in any embodiment of the air filtering device.

To simplify some aspects of the display, emotes or 'smiley faces' may be used to convey at a glance whether a particular reading or measurement is below a warning threshold, for example.

The motor and impeller in the device may controlled to operate in a way that minimises the noise of the device, so that it does not disturb a sleeping infant or prevent them from sleeping. The sound may be less than 50dB, and preferably less than about 40dB.

The motor and impeller may be set to run at a slower speed to help achieve this.

Figures 15 and 16 illustrate the same device 500 of Figures 13-14 but mounted or clipped upright to a pushchair 602 instead of a cot. Again, there is a cover 604 (which may be transparent) over the pushchair to restrict the entry of unfiltered air into the interior region of the pushchair.

A suitable aperture or gap is again provided to allow filtered air to pass from the device 500 into the region where a child or infant is located in the pushchair 602.

In some embodiments, a smartphone app may be provided to allow information about the inbound and/or outbound air quality (particulate matter, total VOCs etc.) to be accessed remotely. Other information such as remaining battery charge and/or expected remaining air filter lifetime may also be available in addition to or instead of air quality information.

The app may allow for remote activation and deactivation of the air filtering device. The app may allow for remote setting of the air flow rate or operational mode of the air filtering device.

In some embodiments, the device may include a data logger. If the device is used indoors (possibly in multiple locations at different times), the data logging capability may be used to create or visualise a map showing where indoor pollution or contaminants tend to accumulate and/or when during the day the same occurs. This may allow the user to take remedial action to minimise future accumulation of contaminants indoors, or target use of the device to achieve the same.

The embodiments described above are provided by way of example only, and various changes and modifications will be apparent to persons skilled in the art without departing from the scope of the present invention as defined by the appended claims.

Claims

CLAIMS 2. 3. 4. 5. 6. 7.A portable air filtering device for directing filtered air to a person, the device comprising a housing including a body portion and a head portion which is connected to the body portion, an air inlet in the housing for air to enter the housing, an air filter within the housing for filtering air received from the air inlet, an impeller in the housing for conveying air through the air inlet and air filter, and a motor for powering the impeller, and an air outlet at a distal end of the head portion of the housing for receiving filtered air under positive pressure from the impeller, in which the head portion is rotatably connected to the body portion, or the air outlet is rotatably connected to the head portion, to allow rotation through substantially 360 degrees about a longitudinal axis of the housing for directing the flow of the filtered air during use.
A device as claimed in claim 1, in which the air outlet is moveable or pivotable between a first position for directing filtered air longitudinally out of the device and a second position for directing filtered air laterally out of the device.
A device as claimed in claim 2, in which the air outlet is moveable or pivotable to one or more intermediate positions between the first and second positions for directing filtered air out of the device at an angle.
A device as claimed in any preceding claim, in which the air outlet is a nozzle.
A device as claimed in claim 4, in which the nozzle is integrally formed with the head portion of the housing.
A device as claimed in any preceding claim, in which the air filter comprises a C-shaped cartridge which is releasably secured within the housing.
A device as claimed in any preceding claim, in which the air filter comprises a HEPA filter and a carbon filter.
8. A device as claimed in claim 2, or any of claims 3 to 7 when dependent on claim 2, in which the air outlet includes a conduit and a curved wall connected to the conduit for directing air flow out of the conduit.
9. A device as claimed in claim 2, or any of claims 3 to 8 when dependent on claim 2, in which the head portion includes a recessed section for accommodating the air outlet in the second position.
10. A device as claimed in any preceding claim, in which a display is provided along a side of the housing for displaying information about air quality.
11. A device as claimed in any preceding claim, in which a battery compartment is provided in the housing for receiving a battery to power the motor and impeller.
12. A device as claimed in any preceding claim, in which the housing includes a substantially cylindrical outer surface which is sized to fit in one hand.
13. A device as claimed in any preceding claim, in which the body portion of the housing comprises a bracket or one or more mounting points for mounting the device to at least one of: a wearable harness, a cot and a pushchair.
14. A device as claimed in any preceding claim, in which the air outlet is connected to an elongate tube or conduit, and the elongate tube or conduit is connected to a face mask for supplying filtered air into the face mask, such as a face mask according to any of claims 16 to 24.
15. An air filtering device for mounting to a cot or pushchair for directing filtered air to one or more infants, the device comprising a housing including a body portion and a head portion which is connected to the body portion, an air inlet for air to enter the housing, an air filter within the housing for filtering air received from the air inlet, an impeller in the housing for conveying air through the air inlet and air filter, and a motor for powering the impeller, and an air outlet at a distal end of the head portion of the housing for receiving filtered air under positive pressure from the impeller and for directing the filtered air into the cot or pushchair during use, in which the head portion tapers or narrows from the body portion towards the air outlet.
16. A face mask for breathing filtered air, the face mask comprising an inner member including a breathing portion for fitting over at least a person's mouth and/or nose, an outer covering over the inner member, a first port at a first side of the face mask for receiving filtered air under positive pressure from a portable air filtering device, and air flow channelling in the face mask including: a first main channel connected to the first port, and a first plurality of secondary channels which are connected to the first main channel and arranged across the breathing portion for distributing filtered air across the breathing portion during use
17. A face mask as claimed in claim 16, in which the inner member is rigid, and the air flow channelling is provided by at least the rigid inner member.
18. A face mask as claimed in claim 16 or claim 17, in which a second port is provided at a second side of the face mask, and the air flow channelling includes: a second main channel connected to the second port, and a second plurality of secondary channels which are connected to the second main channel and arranged across the breathing portion.
19. A face mask as claimed in claim 18, in which the first and second ports are interchangeably configurable as an air inlet port and an air outlet port respectively.
20. A face mask as claimed in claim 18 or claim 19, in which the first and second pluralities of secondary channels are provided in an interdigitafing arrangement for air flow respectively into and out of the face mask.
21.A face mask as claimed in any of claims 18 to 20, in which the second port includes a one-way valve which is configured to in use close during inhalation and open during exhalation, and the one-way valve optionally includes a NEPA filter for filtering exhaled air.
22. A face mask as claimed in any of claims 16 to 21, in which slots are provided in the breathing portion, and the slots are aligned with at least the first plurality of secondary channels.
23. A face mask as claimed in any of claims 16 to 22, in which a flexible seal is provided on the inner member for sealing against a person's face.
24. A face mask as claimed in any of claims 16 to 23, in which the outer covering is a fabric member comprising means for securing the face mask to a person's head.
25. A kit comprising a portable air filtering device as claimed in any of claims 1 to 14, and a face mask as claimed in any of claims 16 to 24, optionally including an elongate conduit for connecting the face mask to the portable air filtering device.