GB2451278A

GB2451278A - Air quality monitoring and alarm devices

Info

Publication number: GB2451278A
Application number: GB0714561A
Authority: GB
Inventors: Faiz Zishaan
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-07-26
Filing date: 2007-07-26
Publication date: 2009-01-28
Also published as: GB0714561D0

Abstract

Air quality monitoring and alarm devices comprises a sensor exposed to air; an activator for activating the unit; a controller; a communication means between the sensor and controller; and an alarm triggered by sensor signals. The device may be portable and may have a housing with a sensor holder to position the sensor at a variable spaced apart distance from said housing, possibly by telescopic or folding means. The device may include clock means with timer functions; display means to show one or more of time, air quality, the fluctuating air quality measurement over time. A plurality of alarm signal may be provided which may be chosen depending on the time evolution of the air quality measurement. Recoding means may record the time of alarm events or the period when a hazard was sensed. The device may transmit a wireless signal. Physical characteristics of a user may be stored by the device and plural operational modes of the device may correspond to these characteristics. The device may comprise a travel alarm or dictation machine. Air quality sensing may comprise sensing of toxic gasses, such as carbon monoxide, vapours, particulate pollutants and smoke.

Description

Air Quality Monitoring units

Field of the Invention

:... The invention relates to air quality monitoring units. S... * . S...

:. Background to the Invention and Prior Art known to the Applicant * 20 S..

Walt mountable carbon monoxide detectors are well known. These generally incorporate a :. sensor exposed to air; an activator for activating the unit; a controller; a communication channel for communicating signals representative of the sensed air quality from the sensor to the controller; and an alarm which is triggered by the controller dependent upon the signals received from the sensor. The prior art carbon monoxide detector usually requires a connection to the electrical grid and is designed to be wall mountable. The sensor also usually triggers a single kind of alarm of an audible kind. A green LED (light emitting diode) might be provided to indicate that the system is operating correctly whilst a red LED would be illuminated to indicate a fault in the prior art system. No historical information can be obtained from the device since after a period of alarm the detector

Summary of the Invention

In a first broad independent aspect, the invention provides an air quality monitoring unit comprising a sensor exposed to air; an activator for activating the unit; a controller; a communication channel for communicating signals representative of said sensed air quality from said sensor to said controller; arid an alarm which is triggered by said controller dependent upon the signals received from said sensor; wherein the unit further comprises a housing incorporating said alarm, and a sensor holder which allows the sensor to be held at a variable spaced apart distance from said housing.

This feature is particularly advantageous as it allows the unit housing to be placed in a location which may not be exposed to the optimum air flow for detection whilst the sensor may be placed in a location where advantageous sensing may take place In a subsidiary aspect in accordance with the invention's first broad independent aspect the unit incorporates a holder in the form of a telescopic member. In a further subsidiary :. aspect, the sensor holder may be provided with a portion which may extend, spring, open, fold or swivel out in order to extend the distance between the housing and the sensor. S..

This may take the form of foldout /swivel arrangements of the kind employed by some mobile phone providers. S..

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: * In a second broad independent aspect, the invention provides an air quality monitoring * " unit comprising a sensor exposed to air; an activator for activating the unit; a controller, a communication channel for communicating signals representative of said sensed air quality from said sensor to said controller; and an alarm which is triggered by said controller dependent upon the signals received from said sensor; wherein the unit further comprises one or more indicators for indicating time and an air quality level.

This feature is pamcuiariy advantageous because it increases user interaction and familiarity with units, lithe time indicator tdkes the form of a clock, it will for example be constantly referred to throughout the day by an observer who would therefore detect a potential hazard before any audible alarm would be triggered.

In a third broad independent aspect, the invention provides an air quality monitoring unit comprising a sensor exposed to air; an activator for activating the unit; a controller; a communication channel for communicating signals representative of said sensed air quality from said sensor to said controller; and an alarm which is triggered by said controller dependent upon the signals received from said sensor; wherein said controller incorporates a time keeping device; a communication interface for inputting signals for triggering a future mode of operation, and a trigger for triggering a mode of operation dependent upon the reaching of a predetermined time.

This configuration is particularly advantageous because it allows the unit to potentially function as a calendar, an organiser and a reminder. In this subsidiary aspect, it will allow the unit to inform an observer of the need for an annual appliance (for example a boiler) service. It would also allow the operational mode to be controlled in order to be active during operator selected periods such as during the night. This would be particularly beneficial if the device is used as a travel air quality monitoring unit since it would avoid the batteries being used during transportation. S. * S * *t*

This configuration is particularly advantageous because it also allows the recording of the *5S date and time of the last time the unit itself was tested whilst allowing a reminder for the :. 20 ne>ct test to be entered. I..

In a fourth broad independent aspect, the invention provides an air quality monitoring : *.. unit comprising a sensor exposed to air; an activator for activating the unit; a controller; a communication channel for communicating signals representative of said sensed air quality from said sensor to said controller; and an alarm which is triggered by said controller dependent upon the signals received from said sensor; wherein said unit further comprises means for causing said controller to obtain signals representative of said sensed air quality at a plurality of points in time; means for storing a plurality of alarm signals; and means for selecting said alarm signals dependent upon the evolution through time of said signals representative of said sensed air quality.

This configuration is particularly advantageous because it allows intelligent and measured responses. For example, when the sensor is a carbon monoxide sensor, the unit of this configuration can assess whether the exposure to carbon monoxide is severe or moderate.

It allows the response of the unit to be tailored to various pre-determined conditions. It also allows the alarm to be selected by the operator for the kind of individual which the air quality monitoring unit is destined to protect. This configuration would for example allow an alarm to be raised inside or outside the room and to be intelligible to children as young as 2 to 3 years with only minimal training. It also allows the operator to select an ascending alarm or a full alarm by pressing an appropriate switch on the unit. In the embodiment where a clock and a monitoring unit are combined, it is likely that the alarm would be sounded in close proximity to a user of the monitoring unit. Therefore, an ascending alarm would be preferred since an immediate alarm blast of a relatively high decibel level would not be sensible or desired. This configuration may be adapted to sound an alarm or a full alarm following a period of critical exposure countdown or during periods where the user was particularly vulnerable or likely to be less alert, such as during sleep.

In a fifth broad independent aspect, the invention provides an air quality monitoring unit comprising a sensor exposed to air; an activator for activating the unit; a controller; a communication channel for communicating signals representative of said sensed air :. quality from said sensor to said controller; and an alarm which is triggered by said controller dependent upon the signals received from said sensor; wherein said unit further . . comprises a recorder for recording signals representative of the time during which a hazard occurred.

This configuration is particularly advantageous because it allows an intermittent fault in a : ... boiler for example to be identified. For example, a boiler may be used for a period of 30 minutes only for the heating of hot water which would not necessarily cause a threshold level of carbon monoxide in a given room which is being monitored to be reached.

In a subsidiary aspect, the unit may also include a means for postponing the triggering of an alarm. This might enable the operator to enter an acceptable exposure time. It would also optionally be able to indicate a recommended evacuation time due to a particular Level of detected air quality. This would allow the co-ordination of rescue efforts for workers and military personnel working in known hazardous areas where potentially not being able to operate is not viable, but at the same time, knowledge of the critical exposure levels wouLd facilitate optimal management of the situation.

In a sixth broad independent aspect, the invention provides an air quality monitoring unit comprising a sensor exposed to air; an activator for activating the unit; a controller; a communication channel for communicating signals representative of said sensed air quality from said sensor to said controller; and an alarm which is triggered by said controller dependent upon the signals received from said sensor; wherein said unit further comprises a recorder for recording signals representative of a change in operational mode during a period of time.

In a seventh broad independent aspect, the invention provides an air quality monitoring unit comprising a sensor exposed to air; an activator for activating the unit; a controller; a communication channel for communicating signals representative of said sensed air quality from said sensor to said controller; and an alarm which is triggered by said controller dependent upon the signals received from said sensor; wherein said unit further comprises a recorder for recording a period during which exposure to hazardous air was sensed and a communication interface for communicating said period to an operator of the unit.

:.::: This configuration is particularly advantageous because it allows the operator to precisely determine the level of exposure. This may for example assist medical staff to determine the best course of treatment to be employed in a given situation. S..

In an eighth broad independent aspect, the invention provides an air quality monitoring : ..* unit comprising a sensor exposed to air; an activator for activating the unit; a controller; a communication channel for communicating signals representative of said sensed air quality from said sensor to said controller; and an alarm which is triggered by said controller dependent upon the signals received from said sensor; wherein said unit further comprises an indicator for indicating an air quality level, means for causing said controller to obtain signals representative of said sensed air quality at a plurality of points in time, arid rriearis for displaying fluctuations in determined air quality levels.

This would allow the user of the unit to immediately identify critical conditions In a subsidiary aspect in accordance with the eighth broad independent aspect, the means for displaying fluctuations may take the form of an intelligent and constantly changing read out which would provide visual confirmation that the unit is functioning properly.

In a ninth broad independent aspect, the invention provides an air quality monitoring unit comprising a sensor exposed to air; an activator for activating the unit; a controller; a communication channel for communicating signals representative of said sensed air quality from said sensor to said controller; and an alarm which is triggered by said controller dependent upon the signals received from said sensor, wherein the unit further comprises a communication interface for inputting signals representative of characteristics such as sex, weight, age, and health of an individual which would inhabit a monitored space; and a plurality of predetermined operational modes corresponding to such characteristics This would allow the alarm to be tailored to the particular needs of an individual in order to improve the efficacy of the unit.

In a tenth broad independent aspect, the invention provides an air quality monitoring unit comprising a sensor exposed to air; an activator for activating the unit; a controller; a communication channel for communicating signals representative of said sensed air quality from said sensor to said controller; and an alarm which is triggered by said :. controller dependent upon the signals received from said sensor; wherein said unit further comprises a vibrator alarm for causing the unit to vibrate. * **.

This configuration is particularly advantageous because it would allow the detection of a hazard to be felt; it would be particularly advantageous for the hearing impaired or the partially sighted.

In an eleventh broad independent aspect, the invention provides an air quality monitoring unit comprising a sensor exposed to air; an activator for activating the unit; a controller; a communication channel for communicating signals representative of said sensed air quality from said sensor to said controller; and an alarm which is triggered by said controller dependent upon the signals received from said sensor; wherein said unit incorporates lighting means acting as a visual alarm. This configuration is particularly advantageous because it allows the unit to be effective in communicating the presence of a hazard for the hearing impaired.

n a twelfth broad independent aspect, the invention provides an air quality monitoring unit comprising a sensor exposed to air; an activator for activating the unit; a controller; a communication channel for communicating signals representative of said sensed air quality from said sensor to said controller; and an alarm which is triggered by said controller dependent upon the signals received from said sensor; wherein said unit incorporates a wireless transmitter for sending a signal representative of the unit's status to a wireless receiver.

This configuration is particularly advantageous because it allows remote monitoring to occur. This would particularly be beneficial if the wireless link is to a mobile phone through a mobile network so that for example parents can monitor a room where a child is sleeping without necessarily having to see the monitor or even being in the audible range forthe alarm.

The invention also provides a dictation machine incorporating an air quality monitoring unit according to any of the preceding aspects. This combination of features is particularly advantageous because during operation of the dictation machine a user is required to pay particular attention to its display. It also may be configured with only minimal :. components added to the basic dictation machine structure. For example, the loud * S..

speaker of the dictation machine may be used both to listen to the play-back of recordings and for sounding the alarm. In addition, if the dictation machine is configured optionally with a vibrator, it would allow the operator to immediately sense through his/her hand 20 whilst holding the machine that a hazard is present. S.

The invention also provides a travel alarm incorporating an air quality monitoring unit * ** according to any of the preceding aspects. A number of special advantages arise when incorporating an air quality monitoring unit into a travel alarm. When for example the travel alarm incorporates a loud speaker, the loud speaker may be configured to sound an alarm relating to a hazardous air quality and alternatively sound an alarm for waking the user in conventional fashion. It also allows the air quality monitoring alarm to be naturally positioned in close proximately to a user for example on the top of a bedside cabinet in order to achieve a more efficient form of communication between the unit and its user. In one embodiment, it also allows a user to assess time and the current air quality in a single glance thus improving user awareness and likely response time to any impending hazard.

Detailed Description

The following embodiments are envisaged.

Integrated Detector Incorporating the air quality monitoring unit into a portable device has at least the following benefits: * Increased usage through portability, utility (particularly when incorporated into a travel clock function) and availability; * Allows keeping next to steeping /farriily so that the detection range may be smaller and similarly, the alarm response may be less than a typical 85 decibels; * The alarm mode is preferably an ascending volume mode; * An activator may be provided on the unit to switch the unit on and off so that the *:::: detection facility may be switchable to conserve battery life during less risky periods; for example whilst the monitoring unit is packed in a suitcase or during : ... daylight hours; 20 * It also allows selling at retail outlets for time pieces at points of travel; the number : * of these points of travel far exceed outlets for conventional detector devices which :*:; are not considered travel necessities but largely DIY (do it yourself) or home * improvement products.

An air quality monitoring unit incorporates a sensor which may sense air quality by assessing the presence of one or more of the compounds selected from the group comprising: gas, carbon dioxide, carbon monoxide, smoke, methane, particulate pollution, ground-level ozone, sulphur oxides, nitrogen oxides, lead, hydro carbons, petrol vapour, ammonia, butane, hydrogen/acetylene, chlorine, ethylene oxide, hydrogen, hydrogen chLoride, hydrogen cyanide, hydrogen sulphide, oxygen, ozone, sulphur dioxide, flammable gases, toxic gases, and any pollutants.

Advantageously, the air quality monitoring unit is an integral part of a portable /mobile device. The air quality monitoring unit may advantageously be an integral part of one at least of the articles selected from the group comprising: travel docks, mobile phones, personal digital assistants (PDA), satellite navigational systems, torches (such as those used by fireman and rescue workers), portable breathing /medical devices (for example respirators etc) baby monitors, barometers, thermometers, doorbell chimes, dictation machines, diagnostic tools, attack alarms, power tools, travel irons, and calculators.

Integrated Fixed Devices The air quality monitoring unit is particularly advantageous when incorporated in an article selected from the group comprising: clocks, barometers, thermometers, doorbell chimes, in a home, an office, a garage, a mobile home, a recreational home, vehicles, a bike, a boat, a car, a caravan, a truck, a car radio /information display system. The invention is particularly advantageous when the air quality monitoring unit is incorporated into road going vehicles when the sensor is selected to be for detecting the exposure to carbon monoxide, smog, or other pollutants which are present on modern streets. A bike would he particularly advantageous when incorporating a carbon monoxide /smog monitoring unit for displaying values of the sensed air quality. An aircraft system would also be * S..

particularly advantageous when incorporating as part of one of its information displays, a : c... display of the exposure of carbon monoxide, smog, or other pollutants. * 20

The benefits of integrating an air quality monitoring unit into a fixed device include at least the following: * Opportunity for hanging in prominent locations such as for example kitchen entrance, bedroom, children's bedroom, offices, hotel room; * Opportunity to present critical information to a user at a convenient level.

General Benefits An air quality monitoring unit of the kind in question which comprises a sensor exposed to air, an activator for activating the unit, a controller, a communication channel for communicating signals representative of said sensed air quality from said sensor to said controller, and an alarm which is triggered by said controller dependent upon the signals received from said sensor has the following benefits: * An increased option of detection units generally since they do not necessarily require mounting on a wall or connecting to the electrical mains suppty, * Increased user interaction /familiarity with the units, for example when incorporated in a clock, a user would constantly refer to the clock and to the sensed air quality reading which would therefore lead to a rapid response from a user even before a critical threshold is breached; * Safer when deployed as a personal unit because of greater confidence in correct use, proper and regular testing and care; * The air quality monitoring unit optionally incorporates both an indicator for air quality at an acceptable level or not; * A carbon monoxide detector or other similar hazard detector which incorporates processing means adapted to tell the time, control the sounding of an alarm, allow the variation of a mode of operation, incorporate a calendar, organiser and a reminder system (for example to organise the annual boiler service or other activities); * A processor or controller incorporating means for recording date and time of a test :. before setting the date and time for a subsequent test; * * Facilitates intelligent and measured responses This is particularly important in the * 20 context of a carbon monoxide sensor incorporated into the air quality monitoring :. unit because unlike smoke, carbon monoxide can range from moderate to severe :**:; exposure and symptoms from chronic to acute. A few moments spent in a car * garage during work daily is potentially in breach of the health and safety recommended levels. A defective flue for a gas appliance in breach of health and safety recommended levels but in a far shorter time scale; * In an air quality environment where carbon monoxide is present at 50 parts per million, the air would be safe according to the United Kingdom's Health and Safety Executive; * At a level of 200 parts per million or in certain circumstances at a level of 70 parts per million, an individual would develop a slight headache within 2 to 3 hours, * In an environment of 400 parts per million, an individual would develop a frontal headache within 1 to 2 hours which would become wide spread in 3 hours; With an environment of air with 800 parts per million, an individual would develop dizziness, nausea, convulsions within 45 minutes and be entirely insensible in 2 hours; The processing means and/or the controller and/or the storage means of the air quality monitoring unit is or are configured to record the time the hazard having been detected, to record the measured changes over any given interval, and to compute the overall exposure time; a Since S parts per million can be dangerous for infants and a level of 70 parts per rriillion would necessitate immediate evacuation, the unit incorporates means for varying the sensitivity of the unit so that the threshold for a given alarm may be lowered or raised dependent upon the intended mode of use, The display portion of the unit may display exposure /evacuation time before serious bodily harm occurs; for example 2 hours or 20 minutes dependent upon the Level detected; this function is achievable when both the hazard detection is recorded and the associated time during which the safety level has been breached; u The unit operating by monitoring both time and hazard would allow rescue workers and/or military personnel to determine the appropriate management of a given situation; :: a An indicator may be provided as part of a user interface on for example a clock; this may take the form of a graphical representation for displaying the threat Level; this :. may be for example an exposure meter; The display may be of a graphical kind which is readily understood by individuals * which may be poisoned and therefore in a confused state and therefore not necessarily simply a reading of a given level of parts per million; The Unit controller may be employed to constantly change the readout in order to provide a user with a visual confirmation that the unit is functioning properly; the constantly changing readout feature is a far more accurate test measure because conventional test buttons in detector units only test the circuitry not the detector component itself; * A user interface and appropriate processing means are envisaged to enable a user to set sex, weight, age, health for units to aid critical exposure fevacuation on time dependent upon the characteristics of an individual; * This would allow criteria to be tailored to for example child's room; and to tailor the alarm mode to generate a more rapid response from the child as well as from his or her guardian; * The air quahty monitoring unit optionally incorporates a vocal alarm and a guidance system particularly tailored for certain age groups; this may take the form of 10 toud beeps and instruction such as "wake up danger" or for example "please leave the room and get help quickly', * The air quality monitoring unit optionally incorporates a vocal alarm; means for recording a personalised alarm, and means for sounding the alarm, * The air quality monitoring unit may optionally incorporate a remote loud speaker to raise an alarm outside of a room for example and a local Loud speaker to raise an alarm inside the room; the alarm inside the room would preferably be tailored to the individual being detected; for example in the case of a child it ought to be intelligible for a child of as young as 2 to 3 years with some training; * The air quality monitoring unit optionally incorporates a switchable alarm between a full alarm and/or an ascending alarm; this would be particularly advantageous when employed in devices which are destined to be used in close proximity to a user when for example an immediate alarm blast at 85 decibels may not be sensible or desired, an alarm response, in line with the critical exposure countdown would be more sensible; :. * A vibrator may optionally be provided or a strobe guard which would be * *.I particularly useful for the hearing impaired; * The air quality monitoring unit advantageously incorporates a transmitter for transmitting an dlarm signal wirelessly for example through Bluetooth technology; * The air quality monitoring unit in its portable form may be located on a bedside table and therefore may not be positioned in an optimal position for monitoring air quality; in this situation a holder which may be in the form of a telescopic arm or a flap which can foldout or swivel out in order to space the sensor away from the main portion of a unit iS envisaged so that the main portion of the unit s located in close proximity to a user and the sensor is located in an optimum position for monitoring air quality; * ft may enclose each of the components of the various aspects of this invention in a single housing with one or more recesses to allow it to be wall mounted on a single picture hook for enhanced detection; Other releasable attachment means are envisaged such as a filamentary touch to close pad on the unit or a magnetic strip for attachment onto a fridge or other material suitable for magnetic attachment; * If the option of a recess is selected an A or W recess shaped recess is preferred which may be located at the centre of the back of a travel clock * The unit may incorporate an auto protect function for night time operation; this may be provided by combining the detection unit with a time keeping device so that for example during a period defined as night time it would have extra sensitivity and/or a different response profile for example by employing a more rapidly ascending alarm volume than daytime operation.

* The unit may incorporate means for being compatible with a wireless network; this would allow intelligent investigation of the hazard source, the communication of a recommended evacuation route, without a requirement for an external computer; the units could compute which detected a hazard first and then monitor spread patterns; a red LED could indicate immediate proximity to a hazard and an amber :... /green could indicate relative safety of an evacuation route; a master unit may be provided with increased memory; * It is also envisaged for the units to have one or more ports such as. USB, memory card, and other suitable medium for computation of data on a personal computer; * The unit may also be water proof or splash proof; :. * The units may also incorporate means to enhance the rate of which air is taken into the unit; such means may be for example a se ries or a single vent or pump located in the clock or other devices. The vents would preferably be located underneath the clock /devices; * The unit would incorporate processing means for event time stamping, which would facilitate triangulation of current threat, tracing of the source of threat, and determining fastest route to evacuate where multiple units are fitted (and/or networked); * Critical exposure countdown (for example: two hours until exposure seriously hazardous", or "evacuate immediately"); * Means for winding up the unit to charge a battery in order to avoid battery replacements; * The units in question can also incorporate a so-called "pack-me" function which is a travel packing assisting system which is fully described in an application filed by the same applicant on the same day as the present application; in its broadest sense the "pack-me" function comprises means for communicating a warning signal to a user which is specific to one or more articles to be packed; and a controller which during a period preceding a user's change of Location triggers the communication of said signal to a user of said system in order to remind a user to pack said article. * S * .5. I... * 5 5*5*

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Claims

1. An air quality monitoring unit comprising a sensor exposed to air; an activator for activating the unit; a controller; a communication channel for communicating signals representative of said sensed air quality from said sensor to said controller; and an alarm which is triggered by said controller dependent upon the signals received from said sensor; wherein the unit further comprises a housing incorporating said alarm, and a sensor holder which allows the sensor to be held at a variable spaced apart distance from said housing.

2. An air quality monitoring unit comprising a sensor exposed to air; an activator for activating the unit; a controller; a communication channel for communicating signals representative of said sensed air quality from said sensor to said controller; and an alarm which is triggered by said controller dependent upon the signals received from said sensor; wherein the unit further comprises one or more indicators for indicating time and an air quality level. * *a. * S **s.

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3. An air quality monitoring unit comprising a sensor exposed to air; an activator for * activating the unit; a controller; a communication channel for communicating signals representative of said sensed air quality from said sensor to said controller; and an alarm :. which is triggered by said controller dependent upon the signals received from said sensor; * *.* *. : wherein said controller incorporates a time keeping device; a communication interface for * inputting signals for triggering a future mode of operation; and a trigger for triggering a mode of operation dependent upon the reaching of a predetermined time.

4. An air quality monitoring unit comprising a sensor exposed to air; an activator for activating the unit; a controller; a communication channel for communicating signals representative of said sensed air quality from said sensor to said controller; and an alarm which is triggered by sa'd controller dependent upon the signals received from said sensor; wherein said unit further comprises means for causing said controller to obtain signals representative of said sensed air quality at a plurality of points in time; means for storing a plurality of alarm signals; and means for selecting said alarm signals dependent upon the evolution through time of said signals representative of said sensed air quality.

5. An air quality monitoring unit comprising a sensor exposed to air; an activator for activating the unit; a controller; a communication channel for communicating signals representative of said sensed air quality from said sensor to said controller; and an alarm which is triggered by said controller dependent upon the signals received from said sensor; wherein said unit further comprises a recorder for recording signals representative of the time during which a hazard occurred.

6. An air quality monitoring unit comprising a sensor exposed to air; an activator for activating the unit; a controller; a communication channel for communicating signals representative of said sensed air quality from said sensor to said controller; and an alarm which is triggered by said controller dependent upon the signals received from said sensor; wherein said unit further comprises a recorder for recording signals representative of a change in operational mode during a period of time.

7. An air quaLity monitoring unit comprising a sensor exposed to air; an activator for activating the unit; a controUer; a communication channel for communicating signals *.1 representative of said sensed air quality from said sensor to said controller; and an alarm which is triggered by said controller dependent upon the signals received from said sensor; wherein said unit further comprises a recorder for recording a period during which exposure to hazardous air was sensed and a communication interface for communicating said period to an operator of the unit. * ** . * *

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* 8. An air quality monitoring unit comprising a sensor exposed to air; an activator for activating the unit; a controller; a communication channel for communicating signals representative of said sensed air quality from said sensor to said controller; and an alarm which is triggered by said controller dependent upon the signals received from said sensor; wherein said unit further comprises an indicator for indicating an air quality level, means for causing said controLler to obtain signals representative of said sensed air quality at a plurality of points in time, and means for displaying fluctuations in determined air quality levels.

9. An air quality monitoring unit comprising a sensor exposed to air; an activator for activating the unit; a controller; a communication channel for communicating signals representative of said sensed air quality from said sensor to said controller; and an alarm which is triggered by said controller dependent upon the signals received from said sensor; wherein the unit further comprises a communication interface for inputting signals representative of characteristics such as sex, weight, age, and health of an individual which would inhabit a monitored space; and a plurality of predetermined operational modes corresponding to such characteristics.

10. An air quality monitoring unit comprising a sensor exposed to air; an activator for activating the unit; a controller; a communication channel for communicating signals representative of said sensed air quality from said sensor to said controller; and an alarm which is triggered by said controller dependent upon the signals received from said sensor; wherein said unit further comprises a vibrator alarm for causing the unit to vibrate.

11. An air quality monitoring unit comprising a sensor exposed to air; an activator for activating the unit; a controller; a communication channel for communicating signals representative of said sensed air quality from said sensor to said controller; and an alarm which is triggered by said controller dependent upon the signals received from said sensor; wherein said unit incorporates lighting means acting as visual alarm.

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12. An air quality monitoring unit comprising a sensor exposed to air; an activator for activating the unit; a controller; a communication channel for communicating signals :. representative of said sensed air quality from said sensor to said controlLer; and an alarm which is triggered by said controller dependent upon the signals received from said sensor; wherein said unit incorporates a wireless transmitter for sending a signal representative of the unit's status to a wireless receiver.

13. A dictation machine incorporating an air quality monitoring unit according to any of the preceding claims.

14. A travel alarm incorporating an air quality monitoring unit according to any of the preceding claims.

15. A unit substantially as hereinbefore described with reference to any appropriate combination of the accompanying text.