Monitoring air quality

Abstract

A system for quantifying an air amount of rebreathing air inhaled by a person is disclosed. The system includes a carbon dioxide sensor responsive to carbon dioxide in air, a heart rate sensor or a respiratory rate sensor responsive to a heart rate or a respiratory rate, respectively, of a person, one or more processors, and one or more storage devices storing machine-readable instructions. The machine-readable instructions may be executed by one or more processors to cause the processors to measure a carbon dioxide concentration in the air using a carbon dioxide sensor, measure a heart rate or respiratory rate of a person using a heart rate sensor or a respiratory rate sensor, respectively, and instructing to perform a calculation operation to quantify an amount of air inhaled by the person based on a measurement of a heart rate or respiratory rate of the person, to quantify an air share of re-breathing air based on a measurement of a carbon dioxide concentration in the air, and quantizing the amount of rebreathing air inhaled by the person on the basis of the quantized amount of air inhaled by the person and the air portion of the rebreathing air.

Description

Technical Field

[0001] The present disclosure relates to monitoring air quality. Background Art

[0002] In an occupied indoor environment, poor ventilation can detrimentally expose occupants to high levels of air previously exhaled by the occupants. High levels of exhaled gases can have adverse effects on people in the indoor environment, for example, exposing them to high levels of exhaled gases such as carbon dioxide, which can impair their cognitive abilities, and / or exposing them to high levels of air pollutants such as viruses. One way to inform occupants of air quality is to provide a metric representing the concentration of constituent gases in the air, such as carbon dioxide concentration. Summary of the invention

[0003] A first aspect of the present disclosure provides a system for quantifying the amount of re-breathed air inhaled by a person, the system comprising: a carbon dioxide sensor responsive to carbon dioxide in the air; a heart rate sensor or a respiratory rate sensor responsive to a person's heart rate or respiratory rate, respectively; one or more processors, and one or more storage devices storing machine-readable instructions, wherein the machine-readable instructions are executable by the one or more processors to cause the processors to: measure the carbon dioxide concentration in the air using the carbon dioxide sensor, measure the person's heart rate or respiratory rate using the heart rate sensor or the respiratory rate sensor, respectively, and instruct the execution of computing operations to: quantify the amount of air inhaled by the person based on the measurement of the person's heart rate or respiratory rate, quantify the air share of re-breathed air based on the measurement of the carbon dioxide concentration in the air, and quantify the amount of air inhaled by the person based on the quantified amount of air inhaled by the person and the quantified air share of re-breathed air.

[0004] Thus, the system is operable to quantify the amount of air inhaled by a person which is re-breathed air, i.e., air previously exhaled by the person. A person advantageously finds "re-breathed volume" to be a relatively informative measure of poor air quality / ventilation. In contrast, a user may find a measure representing the concentration of constituent gases in the air (e.g., carbon dioxide concentration) to be relatively uninformative. For example, they may not know what might be considered a normal or good concentration of a particular gas, and therefore may not recognize the significance of the reported concentration. However, a person may more easily understand the significance of inhaling large amounts of re-breathed air. Thus, a user may more easily identify conditions of poor air quality / ventilation and take practical actions to alleviate the condition, e.g., improving ventilation in a room. Thus, a user's exposure to airborne contaminants resulting from poor ventilation may be desirably reduced.

[0005] The system may include a heart rate sensor and a respiration rate sensor. Thus, the machine-readable instructions may be executed by the processor to cause the processor to measure the heart rate of the person using the heart rate sensor and the respiration rate of the person using the respiration rate sensor, and then quantify the amount of air inhaled by the person based on the heart rate measurement of the person and the respiration rate measurement of the person. Using the heart rate measurement of the person and their respiration rate measurement in calculating the amount of air inhaled may desirably improve the accuracy of the quantification. Alternatively, to reduce cost and / or complexity, the system may include only one of the heart rate sensor and the respiration rate sensor.

[0006] Various hardware components of the system can be co-located in a single component. For example, two or more of a carbon dioxide sensor, a respiratory rate sensor, a heart rate sensor, a processor, and / or a storage device can be incorporated into a single component, such as a portable device. Alternatively, these components can be remote from each other and distributed in different discrete components. For example, one or more sensors can be included in a first device, such as a portable device, and one or more processors or storage devices can be included in one or more other devices, such as a data center. One or more processors can include a single processor, and all machine-readable instructions can be executed by the single processor. Alternatively, one or more processors can include multiple processors, and each processor can execute a corresponding subset of machine-readable instructions. For example, a first processor can be responsible for executing machine-readable instructions to measure the carbon dioxide concentration in the air using a carbon dioxide sensor, and to measure a person's heart rate or respiratory rate using a heart rate sensor or a respiratory rate sensor, respectively. The first processor can then "load" the execution of later computing operations to one or more other processors to perform various quantifications. Similarly, one or more storage devices can include a single storage device that stores all machine-readable instructions. Alternatively, multiple storage devices can be provided, each storing a corresponding subset of machine-readable instructions.

[0007] The air fraction of re-breathed air (which may also be referred to herein as the re-breathing fraction) is an estimate of the fraction of air in the local environment that has previously been inhaled, for example by a person or animal, and then exhaled. This can be calculated using a measurement of the carbon dioxide concentration in the air from a carbon dioxide sensor, and an estimate (or, in some examples, a measurement) of the exhaled carbon dioxide concentration and a reference carbon dioxide concentration. The re-breathing fraction f may be calculated according to the following formula:

[0008]

[0009] Among them C meas is the carbon dioxide concentration measured using a carbon dioxide sensor; C ref is a measurement or estimate of the average or typical carbon dioxide concentration (which may be obtained, for example, from measurements taken outdoors), C exhis a measurement or estimate of the exhaled carbon dioxide concentration. For example, the current average atmospheric carbon dioxide concentration of 415 ppm can be used as C ref The concentration of carbon dioxide in exhaled air can vary from 36,000 ppm to 43,000 ppm, so the middle value of this range (39,500 ppm) can be used as the C exh For example, by using this formula, the system according to an embodiment of the present invention can quantify the fraction of air used as re-breathed air based on the measurement of the carbon dioxide concentration in the air by the carbon dioxide sensor.

[0010] In an example, the system may include an attachment device for attaching one or more of a carbon dioxide sensor, a heart rate sensor, or a respiratory rate sensor to a person. In other words, the system may include a wearable device for attaching to a person. The attachment device may include, for example, a band for encircling a limb of a person, or a garment worn by a person, or an alternative device for attaching to a person.

[0011] By attaching a sensor to a person, the measurement accuracy of the corresponding sensor can be improved. For example, by attaching a carbon dioxide sensor to a person, the sensor can be exposed to the same air that the person breathes in even if the person moves, and can therefore provide a highly representative measurement of the concentration of carbon dioxide in the air that the person breathes in. In contrast, if the carbon dioxide sensor is not attached to the person, for example, if the sensor is located in a static position in the room where the person lives, the sensor may not be exposed to the same air that the person breathes in, at least not for a short period of time. For example, the concentration of carbon dioxide may vary with the area of ​​the room, and therefore the static sensor measurement may not be very representative of the concentration of carbon dioxide in the air to which the person is exposed. Similarly, by attaching one or both of the heart rate sensor and the respiratory rate sensor to the person, the sensors are closer to the person and can therefore provide more accurate measurements, especially if the person moves. In contrast, for example, if the heart rate sensor includes a static sensor, such as an optical camera, the person may move out of the field of view of the sensor, and therefore the sensor measurement will be negatively affected.

[0012] In an example, the system includes a wireless communication interface for interfacing with a wireless communication network, and the machine-readable instructions are executable by one or more processors to cause the processor to output to the wireless communication network through the wireless communication interface: data representing measurements of a person's heart rate or breathing rate and measurements of carbon dioxide concentration in the air, and instructions for performing computing operations.

[0013] In other words, the system may include one or more first processors that execute machine-readable instructions to measure the concentration of carbon dioxide in the air using a carbon dioxide sensor, and to measure the heart rate and / or breathing rate of a person using a heart rate sensor and / or a breathing rate sensor. These one or more first processors may be combined in a device together with various sensors. For example, the sensor and one or more first processors may be combined in a portable device, such as a wearable device. The processor of the first device may then "load" the execution of later computational operations to one or more additional processors to perform various quantifications. Therefore, the processor of the first device may send sensor measurements and instructions for performing later quantification computational operations to one or more additional processors via a wireless communication interface. This "loading" method reduces the computational burden of one or more first processors. This may ideally enable the first processor to have relatively low computational power, and / or may reduce the electrical power consumption of the first processor. Since the size of the first processor and / or the battery powering the first processor may be relatively small, this may ideally enable the device containing the first processor to be relatively compact. This compactness may advantageously facilitate the configuration of the sensor and one or more first processors into a portable bag, for example, into a bag suitable for a person to wear. For example, the wireless communication network may be a Wi-Fi, Bluetooth, Bluetooth Low Energy, or Zigbee network, and the interface may be configured accordingly.

[0014] In an example, the machine-readable instructions are executable by one or more processors to cause the processors to perform computing operations.

[0015] In other words, one or more processors may not simply issue instructions to perform various quantitative computing operations, e.g., "load" instructions to one or more additional processors to perform computing operations. Instead, one or more processors may perform various computing operations themselves. This onboard approach may desirably improve the data security of sensor measurements compared to the aforementioned "load" approach, since they do not need to be shared with other processors, e.g., via a wireless network. In addition, latency or delays in calculations caused by outputting measurements via a network may be avoided.

[0016] In an example, the machine readable instructions are executable by one or more processors to cause the one or more processors to output a representation of the quantized amount of air of the rebreathed air.

[0017] Thus, a user of the system can be informed of the quantified amount of air. For example, the representation can include data representing the quantified amount of air, and the data can be output via the wireless network via the wireless communication interface. As an alternative example, the processor can interface with a visual or auditory output device to output a visual or auditory representation of the quantified amount of air.

[0018] In an example, the system includes an electronic display, wherein the machine readable instructions are executable by the one or more processors to cause the processor to display a visual representation of the air quantification amount of re-breathed air on the electronic display. The visual representation can be easily understood by a user, and thus can allow the user to easily understand the air quantification amount, and thus easily gain an understanding of the air quality / ventilation rate for the area.

[0019] In an example, machine-readable instructions may be executed by one or more processors to cause the processor to: measure atmospheric conditions and / or electromagnetic radiation using a carbon dioxide sensor and / or another sensor, determine whether the measured atmospheric conditions and / or electromagnetic radiation are greater than or less than a reference value, and in response to determining that the measured atmospheric conditions and / or electromagnetic radiation are greater than or less than one of the threshold values, continue to instruct execution of a computing operation, otherwise in response to determining that the measured atmospheric conditions and / or electromagnetic radiation are greater than or less than another of the reference values, delay instructing execution of a computing operation.

[0020] In other words, the system can indicate the execution of computing operations based on the measured atmospheric conditions / electromagnetic radiation. This feature may be desirable to enable the execution of computing operations only under certain conditions. In particular, in some applications, it is desirable to perform computing operations only when the sensor is located inside a building, because issues of ventilation and exposure to high levels of re-breathed air are generally only highly relevant when people are indoors. This is particularly relevant where the system, or at least the portion of the system that includes the sensor, is portable, such as wearable, whereby the system can be carried by a person both indoors and outdoors. Performing computing operations only when the sensor is determined to be indoors can ideally avoid the execution of unnecessary computing operations when the person is outdoors. Thus, unnecessary processor resource consumption and / or power consumption can be reduced.

[0021] Atmospheric conditions / electromagnetic radiation can be a reliable indication of whether the sensor is indoors or outdoors. For example, atmospheric conditions such as gas concentrations in the air, air temperature and / or humidity can reliably vary between indoors and outdoors. For example, in an indoor environment, it can be expected that the concentration of gases such as carbon dioxide in the air may be higher than in an outdoor environment. Therefore, a high concentration of gases such as carbon dioxide in the air can indicate that the sensor is located indoors. Similarly, depending on the climate, it can be expected that the temperature and / or humidity indoors may be lower than outdoors, and vice versa. The presence of high levels of electromagnetic radiation, such as radio frequency radiation originating from a wireless router, can also be considered an indication that the sensor is located indoors. Alternatively, a weak cellular phone signal can be considered an indication that another sensor is indoors. Therefore, the other sensor can be, for example, a cellular transceiver, operable to measure cellular signal strength. Measuring atmospheric conditions can include the above-mentioned operation of measuring the concentration of carbon dioxide in the air using a carbon dioxide sensor. Alternatively, measuring atmospheric conditions can include measuring alternative atmospheric conditions, such as measuring the concentration of an alternative gas in the air using an additional gas sensor, or measuring air temperature and / or humidity using a temperature / humidity sensor, respectively.

[0022] The reference value may thus be a predetermined threshold corresponding to the level of a particular condition to be measured, the particular condition corresponding to an indoor environment. For example, in the case where the atmospheric condition to be measured is the concentration of carbon dioxide in the air, the reference value may be a predetermined value defining a lower limit of the concentration of carbon dioxide in the air, which may be expected to occur in an indoor environment but generally not in an outdoor environment. Thus, in such an example, when the concentration of carbon dioxide or other atmospheric condition metric is determined to be greater than the reference value, indicating that the sensor is located in an indoor environment, the processor may continue to indicate the quantitative calculation operation. Alternatively, in the case where the measured atmospheric condition / electromagnetic radiation level is less than the reference value, indicating that the sensor is located in an outdoor environment, the processor may delay the execution of the indicated calculation operation. In other words, in response to determining that the measured atmospheric condition and / or electromagnetic radiation is greater than or less than the other of the thresholds, indicating that the sensor is outdoors, the processor may introduce a pause, thereby delaying the execution of instructions for the calculation operation. Thus, when the sensor is outdoors, the execution of unnecessary calculation operations is avoided, thereby reducing processor resources and associated processor power consumption.

[0023] In an example, machine-readable instructions may be executed by one or more processors to cause the processor to: measure atmospheric conditions and / or electromagnetic radiation using a carbon dioxide sensor and / or another sensor, repeatedly measure atmospheric conditions and / or electromagnetic radiation using the carbon dioxide sensor and / or another sensor after a period of time has passed since the atmospheric conditions and / or electromagnetic radiation were measured, quantify the difference between the measurement of the atmospheric conditions and / or electromagnetic radiation and the repeated measurement of the atmospheric conditions and / or electromagnetic radiation, determine whether the difference between the measurement of the atmospheric conditions and / or electromagnetic radiation and the repeated measurement of the atmospheric conditions and / or electromagnetic radiation is greater than or less than a threshold difference, and in response to determining that the difference is greater than or less than one of the threshold differences, continue to instruct execution of a computing operation, otherwise in response to determining that the difference is greater than or less than the other of the threshold differences, delay instructing execution of the computing operation.

[0024] In other words, the calculation operation can be performed based on a relative trigger, which is the difference between the measurement and the repeated measurement. This method can ideally compensate for macroscopic changes in the measurement conditions. For example, in the case where the atmospheric condition measured is the air temperature, this method can compensate for different climates because the execution is based on changes in temperature rather than absolute temperature. For example, when a user switches between indoor and outdoor environments, the temperature may change rapidly. For example, in some applications, a rapid and significant increase in temperature can be expected to indicate that the user has entered an indoor environment from an outdoor environment. The step of measuring the atmospheric condition can be the aforementioned step of measuring the carbon dioxide concentration using a carbon dioxide sensor. Optionally, it can include, for example, measuring optional gas concentrations, temperature and / or humidity using additional sensors.

[0025] Therefore, by this method, it is possible to determine whether the sensor is located indoors or outdoors, and when it is determined that the sensor is outdoors, the execution of unnecessary computing operations can be avoided. Therefore, processor resources and associated processor power consumption can be reduced.

[0026] In an example, one or more storage devices store data defining a reference value, and machine-readable instructions are executable by one or more processors to cause the processor to: determine whether a measured concentration of carbon dioxide in the air is greater than or less than the reference value; and in response to determining that the measured concentration of carbon dioxide in the air is greater than or less than one of the reference values, continue to perform instructions for computing operations.

[0027] In an example, the machine-readable instructions may be executed by one or more processors to cause the processor to: in response to determining that the measured concentration of carbon dioxide in the air is greater than or less than the other of the reference values, delay execution of instructions for a computing operation, and repeat measuring the concentration of carbon dioxide in the air using the carbon dioxide sensor after a period of time has passed.

[0028] In an example, the machine-readable instructions may be executed by a processor to cause the processor to provide a prompt to a person to identify whether the person is indoors or outdoors. For example, such a prompt may be provided in response to a determination that the system may be indoors as described above, or such a prompt may be provided periodically or at a particular time of day. Such a prompt may include outputting an indication to a user (e.g., via a display device) indicating that they should input whether they are indoors or outdoors. Thus, this may facilitate determining whether a person is indoors or outdoors, thereby allowing computing operations to be performed only when the person is indoors.

[0029] In an example, the machine-readable instructions may also be executed by one or more processors to cause the processor to instruct retrieval of data defining a physiological characteristic of a person, and quantification of an amount of air inhaled by the person based on a measurement of the person's heart rate or breathing rate includes quantification of an amount of air inhaled by the person based on a measurement of the person's heart rate or breathing rate and the physiological characteristic.

[0030] In other words, the calculation operation used to quantify the amount of inhaled air can further take into account a physiological characteristic of the person, which is a characteristic that is expected to affect the amount of inhaled air. For example, physiological characteristics can include the person's age, gender, or weight. These example characteristics can be expected to affect the person's lung capacity, and therefore can be expected to affect the amount of air inhaled by the person. Therefore, by additionally considering physiological characteristics, the quantification accuracy of the amount of inhaled air can be improved, thereby improving the quantification accuracy of the re-breathing share.

[0031] For example, based on physiological characteristics, the user's minute ventilation rate (V) can be estimated from their heart rate (HR) and gender using the following equation: E ), the ventilation rate is the amount of gas inhaled or exhaled from a person's lungs per minute (e.g., in liters per minute) (see Minute ventilation of cyclists, car and bus passengers: an experimental study; Zuurbier et.al.–Environmental Health, 2009):

[0032] V E(male) =e 1.03+0.021HR (2)

[0033] V E(female) =e 0.57+0.023HR (3)

[0034] In an example where no data defining physiological characteristics is retrieved, the user's minute ventilation rate (V) may be estimated from the user's heart heat (HR) according to the following formula: E) (See An approach to using heart rate monitoring to estimate the ventilation and load of air pollution exposure; Cozza et al; Science of The Total Environment; 2015;520:160–7):

[0035] V E = e 0.58+0 .025HR (4)

[0036] Based on this determined ventilation rate, the total rebreathed air volume RAV for a given time T can be calculated using the rebreathing fraction f according to the following equation:

[0037]

[0038] In an example, the machine readable instructions are executable by one or more processors to cause the processor to: obtain an indication of a number of other persons in the vicinity of the person; and based on a measurement of a concentration of carbon dioxide in the air by a carbon dioxide sensor and based on the indication of the number of other persons in the vicinity, instruct performance of a computing operation to quantify the air share of rebreathed air.

[0039] In other words, quantifying the share of re-breathed air may further take into account the number of other people in the vicinity of the user, e.g. in the same indoor room as the user. This may ideally allow compensating the quantification according to the number of other people who are expected to have exhaled the air inhaled by the person. Thus, the quantification may only reflect the air previously exhaled by others, and not the air previously exhaled by the person themselves. This arrangement may be particularly advantageous as the quantification may be more representative of the virus transmission risk, as the share of re-breathed air attributed to the system user himself is not relevant to virus transmission.

[0040] In this case, the rebreathing fraction f can be calculated according to the following formula:

[0041]

[0042] Where n is the number of people in a given location including the user (which can be referred to here as the occupancy of the room or area), C meas is a measurement of CO2 concentration, such as that measured using a CO2 sensor; C ref is a measurement or estimate of the average or typical carbon dioxide concentration (which may be obtained from measurements taken outdoors, e.g., outdoors), C exh is a measurement or estimate of the exhaled carbon dioxide concentration. For example, the current average atmospheric carbon dioxide concentration of 415 ppm can be used as Cout The concentration of carbon dioxide in exhaled air can vary from 36,000 ppm to 43,000 ppm, so the middle value of this range (39,500 ppm) can be used as the C exh For example, by using this formula, a system according to an embodiment of the present invention can quantify the share of air that is due to rebreathing of other people based on the measurement of the concentration of carbon dioxide in the air by a carbon dioxide sensor and an indication of the number of other people in the vicinity of the person. This can provide improved personalized air quality monitoring, the results of which can be output on an electronic display, as described above.

[0043] In an example, the machine-readable instructions may be executed by a processor to cause the processor to provide a prompt to the person requesting input of the number of other people in their vicinity. For example, as described above, such a prompt may be provided in response to determining that the system is indoors. Such a prompt may include outputting an indication to the user (e.g., via a connected display device) indicating that they should enter the number of other people in their vicinity. For example, the received number may be stored in one or more storage devices. In an embodiment, the person may enter the number into a wearable device or a remote device as described above.

[0044] A second aspect of the present disclosure provides a method for quantifying the air volume of re-breathed air inhaled by a person, the method comprising: measuring the carbon dioxide concentration in the air to which the person is exposed using a carbon dioxide monitor, and measuring the heart rate or breathing rate of the person using a heart rate monitor or a breathing rate monitor, indicating the following quantifications: quantifying the amount of air inhaled by the person based on the measurement of the heart rate or breathing rate of the person, quantifying the share of re-breathed air based on the measurement of the carbon dioxide concentration in the air by the carbon dioxide monitor, and quantifying the air volume of re-breathed air inhaled by the person based on the quantified amount of air inhaled by the person and the quantified share of re-breathed air.

[0045] In an example, the method further comprises measuring atmospheric conditions and / or electromagnetic radiation using a carbon dioxide monitor and / or another monitor, determining whether the measured atmospheric conditions and / or electromagnetic radiation are greater than or less than a reference value, and continuing to indicate quantification in response to determining that the measured atmospheric conditions and / or electromagnetic radiation are greater than or less than one of the thresholds, otherwise delaying indicating quantification in response to determining that the measured atmospheric conditions and / or electromagnetic radiation are greater than or less than another of the thresholds.

[0046] In an example, the method further includes measuring atmospheric conditions and / or electromagnetic radiation using a carbon dioxide monitor and / or another monitor, repeatedly measuring the atmospheric conditions and / or electromagnetic radiation using the carbon dioxide monitor and / or another monitor after a period of time has passed since the atmospheric conditions and / or electromagnetic radiation were measured, determining whether a difference between the measurement of the atmospheric conditions and / or electromagnetic radiation and the repeated measurement of the atmospheric conditions and / or electromagnetic radiation is greater than or less than a threshold difference, and continuing to indicate quantification in response to determining that the difference is greater than or less than one of the threshold differences, otherwise delaying indicating quantification in response to determining that the difference in the measured atmospheric conditions and / or electromagnetic radiation is greater than or less than the other of the threshold differences.

[0047] In an example, the method further includes: determining whether the measured concentration of carbon dioxide in the air is greater than or less than a reference value; and in response to determining that the measured concentration of carbon dioxide in the air is one of greater than or less than the reference value, continuing to instruct performance of the calculation operation.

[0048] In an example, the method further includes, in response to determining that the measured concentration of carbon dioxide in the air is greater than or less than the other of the reference values, delaying the indication of quantification and repeating the measurement of the concentration of carbon dioxide in the air using the carbon dioxide monitor after a period of time has elapsed.

[0049] In an example, the method further includes instructing to retrieve data defining a physiological characteristic of the person, and instructing to quantify the amount of air inhaled by the person based on a measurement of the heart rate or breathing rate of the person includes instructing to quantify the amount of air inhaled by the person based on the measurement of the heart rate or breathing rate of the person and the physiological characteristic.

[0050] In an example, the method further comprises: obtaining an indication of a number of other persons in the vicinity of the person; and indicating a quantification of the air fraction that is rebreathed air based on a measurement of the concentration of carbon dioxide in the air by a carbon dioxide monitor and based on the indication of the number of other persons in the vicinity. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more easily understand the present disclosure, embodiments of the present disclosure will now be described by way of example with reference to the accompanying drawings, in which:

[0052] Figure 1 is a schematic diagram of a system according to an embodiment of the present disclosure;

[0053] Figure 2 is a schematic diagram of a system according to a second embodiment of the present disclosure;

[0054] Figure 3 is a flow chart illustrating a method according to the present disclosure; and

[0055] Figure 4 A computing system in accordance with the present disclosure is depicted. DETAILED DESCRIPTION

[0056] Aspects and embodiments of the present disclosure will now be discussed with reference to the accompanying drawings. Other aspects and embodiments will be apparent to those skilled in the art. All documents mentioned herein are incorporated herein by reference.

[0057] Figure 1 A schematic diagram of a system 100 according to an embodiment of the present invention is shown, which system 100 can be used to monitor air quality by quantifying the amount of re-breathed air inhaled by a person. System 100 includes a carbon dioxide sensor 102 responsive to carbon dioxide in the air; a heart rate sensor 104 responsive to a person's heart rate; a respiration rate sensor 106 responsive to a person's respiration rate; an atmospheric condition sensor 108 responsive to atmospheric conditions such as temperature or humidity; an electromagnetic radiation sensor 110 responsive to electromagnetic radiation, such as visible light or mobile telecommunications network strength; a processor 112 for executing machine-readable instructions to measure and quantify parameters, as explained in more detail below; a storage device 114 for storing machine-readable instructions and any other necessary data; and an electronic display 116, which can display a visual representation of the parameters output from processor 110 in any suitable form for viewing by a person using system 100. The components of system 100 communicate via a communication network 118, which can be a wired network (e.g., a bus), a wireless network, or any combination of wired and wireless networks, depending on how the system is implemented. The system 100 can thus monitor air quality by quantifying the amount of re-breathed air inhaled by a person, as explained in more detail below. Figure 1 Not shown in the figure, the system 100 also includes at least one power source for powering the various components of the system 100. For example, this may be in the form of a mains power supply, or a battery or supercapacitor or the like.

[0058] The carbon dioxide sensor 102 can be any suitable sensor that responds to carbon dioxide in the air, such as a photoacoustic sensor, such as a Sensirion (trademark) SCD4x carbon dioxide sensor. The carbon dioxide sensor 102 thus allows the system 100 to measure carbon dioxide concentrations. Preferably, the system 100 is configured so that the carbon dioxide sensor 102 is located in the air near a person using the system 100 (e.g., the carbon dioxide sensor 102 can be located near the person) to ensure the accuracy of carbon dioxide measurements. The heart rate sensor 104 is preferably a photoplethysmographic sensor or a pulse oximeter, so in some embodiments, the heart rate sensor 104 can be provided in a device that contacts the skin of the person, such as a wearable device. In some embodiments, the heart rate measured using the heart rate sensor 104 can be used to measure or calculate the breathing rate of the person. For example, the device may also include a carbon dioxide sensor 102 so that the carbon dioxide sensor 102 is located near the person.

[0059] exist Figure 1 In the system 100, the respiratory rate sensor 106 is also used to directly respond to and thereby measure the person's respiratory rate, and this measurement can be used to confirm or compare with the measurement of the person's respiratory rate obtained from the heart rate sensor 104 to improve accuracy. For example, the respiratory rate sensor 106 may include a carbon dioxide sensor, a temperature sensor, or an anemometer, which is preferably located near the person's mouth so that the respiratory rate can be inferred based on changes in measurements received from these sensors. In other embodiments, the respiratory rate sensor 106 can be a chest-mounted device that is configured to respond to the expansion and contraction of the person's chest and thereby derive the respiratory rate from these measurements. Optionally, the respiratory rate sensor 106 can be set in a device that is remote from the person, such as an indoor fan, and the person's respiratory rate can be inferred based on images and / or videos captured by a camera system.

[0060] The atmospheric condition sensor 108 and / or the electromagnetic radiation sensor 110 are used to determine whether a person is indoors or in an enclosed space. Outdoor environments may be well ventilated, so the air quality of such environments may be high, so air quality monitoring in these environments would be an inefficient use of the resources of the system 100. By limiting data processing to indoor environments, the resources of the system 100 (e.g., any battery used to power the system 100) can be used more efficiently. In an embodiment, the atmospheric condition sensor 108 can be any one or more of a temperature sensor, a humidity sensor, or an additional carbon dioxide sensor. Such a sensor can be used to determine when a person is indoors, for example by comparing a sensed value with a threshold, or by monitoring changes in the sensed atmospheric conditions over time, which will be explained in more detail below. The electromagnetic radiation sensor 110 can be used in a similar manner to determine whether a person is indoors or in an enclosed environment. For example, the electromagnetic radiation sensor 110 can be sensitive to the signal strength of visible light and / or a mobile telecommunications network, so that it can be determined whether a person is indoors or outdoors based on a comparison of a sensed value with a threshold or by monitoring changes in a sensed value over time. It should be appreciated that in certain embodiments, a system may be provided in which the carbon dioxide sensor 102 is used as the atmospheric condition sensor 108, thereby eliminating the need for an additional sensor.

[0061] It should be noted that the system 100 may be provided as a single device, or components of the system 100 may be provided in different devices. For example, in a preferred embodiment, the carbon dioxide sensor 102 and the heart rate sensor 104 are provided in a portable (e.g., wearable) device having a communication interface for interfacing with a communication network so that processing of the sensed values ​​and display of information to a person may be performed on another device forming part of the system 100. Figure 2Such embodiments are described in more detail. Of course, the system 100 may include more than two devices. For example, in some embodiments, the respiration rate sensor 106 may be disposed in a device that is remote from a person, such as a room fan, to monitor the respiration rate using a camera system.

[0062] Figure 2 A schematic diagram of a system 200 according to a second embodiment of the present invention is shown, which system 200 can be used to monitor air quality by quantifying the amount of re-breathed air inhaled by a person. In this embodiment, the system 200 includes a wearable device 210 and a smartphone 220, which communicate with each other via a communication network shown by arrow 230. The person can input additional data 240 to the system 200 by interacting with the smartphone 220. For example, an application can be run on the smartphone 220 for receiving information from and presenting information to the person using the system.

[0063] Wearable device 210 includes an accessory device in the form of a band 216 for attaching wearable device 210 to a person. For example, band 216 may be sized to fit around a person's arm, such as around a person's upper arm or wrist. In some embodiments, band 216 may be sized to fit around a person's chest, which may be particularly advantageous in embodiments where system 200 is configured to track a person's respiratory rate by measuring the expansion and contraction of a person's chest. Housing 218 is mounted on band 216, which houses carbon dioxide sensor 212 and heart rate sensor 214. In some embodiments, heart rate sensor 214 may be a photoelectric plethysmographic sensor or a pulse oximeter that requires contact with a person's skin. Of course, other suitable sensors, such as electronic heart rate monitors, may also be used. Housing 218 also houses one or more processing devices, one or more storage devices, and a wireless communication interface for docking with a wireless communication network shown by arrow 230, as well as a power source, such as a battery, for powering all components present in wearable device 210. Thus, the wearable device 210 can perform some processing using one or more processors located in the housing 218, but preferably, the wearable device 210 transmits data to the smartphone 220 where the majority of the data processing is performed because the smartphone 220 is likely capable of performing faster and more efficient data processing. In this way, the one or more processing devices on the wearable device 210 can be optimized for efficiency rather than performance, so the battery life of the wearable device can be extended.

[0064] Specifically, the wearable device 210 is configured to monitor and measure the carbon dioxide concentration in the air using the carbon dioxide sensor 212, and to monitor and measure the heart rate of the person using the heart rate sensor 214. The wearable device 210 can then communicate these measurements to the smartphone 220 via the communication network shown by the arrow 230, so that the smartphone 220 can quantify the amount of re-breathed air inhaled by the person as described below. By being provided in part as a wearable device 210, the system 200 is able to sense and measure the carbon dioxide concentration near the person, thereby providing accurate and personalized air quality monitoring.

[0065] In some examples, the carbon dioxide sensor 212 can also be used to determine when a person is indoors or in an enclosed space. For example, the carbon dioxide sensor 212 can periodically or repeatedly measure the carbon dioxide level, and one or more processors on the wearable device 210 (or on the smartphone 220) can compare the sensed carbon dioxide level with a threshold to determine whether the person is indoors or outdoors. For example, if it is determined that the sensed carbon dioxide concentration is greater than a stored threshold (e.g., 415ppm), it can be determined that the person is indoors. In another example, one or more processors can quantify the difference between repeated measurements of carbon dioxide levels, and if the difference is greater than a threshold level, it can be determined that the person is indoors. In some examples, in response to determining that the person is indoors, the system 200 can only continue to quantify the share of air as rebreathed air and the amount of air that the person inhales. This can ensure that system resources (particularly energy from a battery power source) are used efficiently. The repetition frequency of such measurements to determine whether the user is indoors can be adjusted by the user, such as through a smartphone application. Adjustment of the time between subsequent measurements can be used to balance the responsiveness of the system 200 to when a person enters the room while saving power from the battery on the wearable device 210.

[0066] Smartphone 220 can be any suitable smart phone, such as Apple iPhone (trademark), Samsung Galaxy (trademark), etc. Specifically, smart phone 220 can be equipped with a dedicated application, which is configured to be compatible with wearable device 210. Smartphone 220 includes one or more processors and one or more storage devices and a wireless communication interface for docking with the wireless communication network shown by arrow 230. Smartphone 220 also includes an electronic display 222, which can be a touch screen display to display a visual representation of the air quantization amount of re-breathed air to the person. The person can also enter additional data 240 by interacting with smartphone 200, such as by interacting with electronic display 222. Such additional data 240 can include physiological characteristics of the person, and / or an indication of the number of other people near the person. The application can be configured to provide visual prompts to the user on the electronic display 222, requiring them to enter certain data. For example, the application can prompt the user to confirm whether they are indoors (e.g., confirming that a determination has been made based on sensors in wearable device 210 or smart phone 220), and / or enter the number of other people near the user.

[0067] When smartphone 220 has received the measurement of carbon dioxide concentration and the person's heart rate from wearable device 210, smartphone 220 executes instructions stored in one or more storage devices to quantify the amount of air inhaled by the person based on the person's heart rate, quantify the air share of re-breathed air based on the measurement of carbon dioxide concentration, and quantify the amount of air inhaled by the person. In particular, smartphone 220 uses equation (1) given above, where the measured carbon dioxide concentration received from wearable device 210 is used as the value of the measured carbon dioxide concentration (C meas ), and the reference values ​​stored in one or more storage devices are used for the reference carbon dioxide concentration and the exhaled carbon dioxide concentration (respectively C ref and C exh ) to quantify the fraction of air that is re-breathed air. If the person has entered additional data 240 to indicate the number of other people in their vicinity, the smartphone 220 may additionally or alternatively use equation (6) to quantify the fraction of air that is re-breathed air due to other people in the vicinity.

[0068] The additional data 240 may also include the person's gender, enabling the smartphone to quantify the person's minute ventilation rate (V) using equation (2) or equation (3) given above. E), where the measured heart rate received from wearable device 210 is used as the heart rate (HR). Of course, if the person does not enter such data, then equation (4) can be used. This allows the smartphone to quantify the amount of air the person inhales based on the heart rate by quantifying the person's minute ventilation rate. In some examples, the person's vital capacity or tidal volume (i.e., the amount of air the person inhales during normal breathing), or physical information that allows their vital capacity or tidal volume to be calculated or estimated, can also be entered as additional information 240. After quantifying the amount of air the person inhales and the air share of re-breathed air, smartphone 220 is able to quantify the amount of air the person inhales as re-breathed air. When smartphone 220 has quantified this information, the information can be reported to the user via electronic display 222.

[0069] In some embodiments, a person's breathing rate can be measured directly, such as by a breathing rate sensor. To quantify a person's minute ventilation rate from the breathing rate, the measured breathing rate (in units of breaths per minute) needs to be multiplied by the tidal volume. It should be noted that tidal volume is different from vital capacity because typical breathing does not use the entire lung capacity.

[0070] The tidal volume of a person may be estimated or calculated (e.g., calculated based on data defining physiological characteristics of the person). For example, an average tidal volume of 500 mL may be assumed (see, e.g., Beardsell, I et al: MCEM Part A: MCQs, page 33, Royal Society of Medicine Press, 2009), or an estimate may be retrieved from a database based on physiological characteristics of the person (e.g., age, weight, gender). In another example, the tidal volume (V) of a person may be calculated based on the person's physiological characteristics. T , in mL) can be calculated based on their body weight (W, in Kg) according to the following equation (Impact of Height Estimation on Tidal Volume Calculation for Protective Ventilation—A Prospective Observational Study; Andre R. Alexandre et al; Critical Care Explorations; May 2021; 3(5); e0422):

[0071] V T =(6.2±0.5)W (7)

[0072] Where 6.2mL / Kg is the mean tidal volume per kilogram of body weight and 0.5mL / Kg is the standard deviation. So, for example, a person's tidal volume can be assumed to be 6.2 mL per kilogram of body weight.

[0073] Smartphone 220 may also provide additional sensing capabilities to system 200. For example, smartphone 220 may include sensors that respond to atmospheric conditions such as humidity or temperature, or sensors that respond to electromagnetic radiation such as visible light such as mobile network strength. Such sensors may be used in addition to, or in lieu of, carbon dioxide sensor 212 to determine whether a person is indoors or outdoors. For example, sensed light intensity, humidity, temperature, and / or mobile network strength may be compared to thresholds to determine whether smartphone 220, and therefore a person, is indoors or outdoors. The sensed parameters may also be repeatedly measured over time, and changes in the measurements may be used to determine whether a person is indoors or outdoors.

[0074] The communication network indicated by arrow 230 can be any suitable wired or wireless communication network. For example, wearable device 210 can communicate with smartphone 220 via a universal serial bus (USB) connection, a Bluetooth connection, a Wi-Fi connection, or any other such communication network or protocol. Of course, wearable device 210 and smartphone 220 can each be configured to communicate via multiple communication networks.

[0075] Figure 3 is a flow chart showing a method 300 for quantifying the amount of re-breathed air inhaled by a person according to an embodiment of the present invention, and the method may be performed by an air quality monitoring system, such as Figure 1 The system 100 or Figure 2 System 200 is shown.

[0076] In a first step 302, the method 300 measures the carbon dioxide concentration to which the person is exposed. The carbon dioxide concentration is detected by a carbon dioxide sensor (e.g., a photoacoustic sensor) in the wearable device, and an associated processor can use the sensor to measure the carbon dioxide concentration. Then, in step 304, the measured carbon dioxide value is used to determine whether the person is indoors. For example, the measured carbon dioxide value can be compared with a threshold value (e.g., 415ppm, which can be used as an average outdoor carbon dioxide concentration), and if the carbon dioxide concentration is greater than the threshold value, it can be considered that the person is indoors, and the method can continue to step 308 ("yes"). Alternatively, if the measured carbon dioxide level is equal to or lower than the threshold value, it can be considered that the person is outdoors, so that air quality monitoring is not required, and the method can be paused for a predetermined time period at step 306 ("no"). When the predetermined time period has passed, the method returns to step 302 and further measures the carbon dioxide concentration. As an alternative or in addition to comparing the carbon dioxide value with the threshold value, step 304 may include monitoring how the measured carbon dioxide level changes over time. For example, the difference between consecutive carbon dioxide readings can be compared with the threshold level change to determine whether the person is indoors. For example, a difference between consecutive readings that is greater than a threshold change may indicate that a person has moved indoors.

[0077] In this way, further processing is performed only when it is determined that a user may be in a room where air quality monitoring is required. Steps 302, 304, 306 thus form a processing loop. This can improve the efficiency of the system performing the method because system resources are only utilized when needed.

[0078] When step 304 determines that the person is indoors, processing continues and the person's heart rate is measured at step 308. For example, the person's heart rate can be detected by a heart rate sensor, such as a photoplethysmography sensor in a wearable device. It should be understood that in some embodiments, in step 308, the person's respiratory rate is measured in addition to or instead of heart rate. However, by measuring the heart rate at step 308, the minute ventilation rate can be estimated, for example, according to equations (2) and / or (3). Specifically, in order to allow quantification of the respiratory rate, in step 310, the physiological characteristics can be retrieved, for example, from a storage device.

[0079] In step 312, the amount of air inhaled by the person is quantified based on the heart rate measured in step 308. Specifically, the minute ventilation rate is quantified, for example, according to equation (2) or (3), so the amount of air inhaled by the person can be quantified by determining the relevant time period.

[0080] Based on the carbon dioxide concentration measured in step 302, the air share of rebreathed air is quantified in step 314. In other examples, another measurement of carbon dioxide concentration may be made, independent of the measurement used to determine whether a person is in the room. For example, step 314 may involve quantifying the rebreathed share according to equation (1) given above, where the measured carbon dioxide concentration is used as the value of the measured carbon dioxide concentration (C meas ), and the reference values ​​stored in one or more storage devices are used for the reference carbon dioxide concentration and the exhaled carbon dioxide concentration (respectively C ref and C exh ) in order to quantify the fraction of air that is re-breathed air. In some embodiments of the method, a person may indicate the number of other people in their vicinity, so that equation (6) may be used to quantify the fraction of air that is re-breathed air due to other people in the vicinity.

[0081] Based on the amount of air inhaled by the person quantified at step 312 and the air share of the re-breathed air quantified at step 316, the amount of air inhaled by the person is quantified at step 316. For example, the amount of re-breathed air inhaled by the person can be quantified as an amount of air per minute or any time period. This information can be displayed to the person, for example, in a video as described above with reference to FIG. Figure 2 on the electronic display.

[0082] Figure 4 An example computing system 1000 is depicted. The following description of computing system 1000 is provided by way of example only and is not intended to be limiting.

[0083] The example computing system 1000 includes a processor 1004 for executing software routines. Although a single processor is shown for clarity, the computing system 1000 may also include a multi-processor system. The processor 1004 is connected to a communication infrastructure 1006 for communicating with other components of the computing system 1000. The communication infrastructure 1006 may include, for example, a communication bus, a crossbar switch, or a network.

[0084] The computing system 1000 also includes a main memory 1008, such as a random access memory (RAM), and a secondary memory 1010. The secondary memory 1010 may include, for example, a hard disk drive 1012 and / or a removable storage drive 1014, which may include a floppy disk drive, a tape drive, an optical disk drive, a solid-state memory, etc. The removable storage drive 1014 reads from and / or writes to a removable storage unit 1018 in a well-known manner. The removable storage unit 1018 may include a floppy disk, a tape, an optical disk, a removable solid-state memory (e.g., an SD card), etc., which is read and written by the removable storage drive 1014. Those skilled in the relevant art will appreciate that the removable storage unit 1018 includes a computer-readable storage medium having computer-executable program code instructions and / or data stored therein.

[0085] In alternative implementations, the secondary memory 1010 may additionally or alternatively include other similar means for allowing computer programs or other instructions to be loaded into the computing system 1000. Such means may include, for example, a removable storage unit 1022 and an interface 1020. Examples of removable storage units 1022 and interfaces 1020 include program cartridges and cartridge interfaces (such as found in video game console devices), removable storage chips (such as EPROMs or PROMs) and associated sockets, and other removable storage units 1022 and interfaces 1020 that allow software and data to be transferred from the removable storage unit 1022 to the computer system 1000.

[0086] The computing system 1000 also includes at least one communication interface 1024. The communication interface 1024 allows software and data to be transmitted between the computing system 1000 and external devices via a communication path 1026. In various embodiments, the communication interface 1024 allows data to be transmitted between the computing system 1000 and a data communication network such as a public data or a dedicated data communication network. The communication interface 1024 can be used to exchange data between multiple different computing systems 1000 that form an interconnected computer network together. Examples of the communication interface 1024 can include a modem, a network interface (such as an Ethernet card), a communication port, an antenna with related circuits, etc. The communication interface 1024 can be wired or can be wireless. The software and data transmitted via the communication interface 1024 are in the form of a signal, which can be electronic, electromagnetic, optical or other signals that can be received by the communication interface 1024. These signals are provided to the communication interface via a communication path 1026.

[0087] like Figure 4As shown, the computing system 1000 further includes a display interface 1002 and an audio interface 1032 . The display interface 1002 performs operations of presenting images to an associated display 1030 , and the audio interface 1032 performs operations of playing audio content through an associated speaker 1034 .

[0088] As used herein, the term "computer program product" may refer in part to removable storage unit 1018, removable storage unit 1022, a hard disk installed in hard disk drive 1012, or a carrier wave carrying software through communication path 1026 (wireless link or cable) to communication interface 1024. Computer readable media may include magnetic media, optical media or other recordable media, or media that transmit carrier waves or other signals. These computer program products are devices for providing software to computing system 1000.

[0089] Computer programs (also referred to as computer program code) are stored in the main memory 1008 and / or the secondary memory 1010. The computer programs may also be received via the communication interface 1024. Such computer programs, when executed, enable the computing system 1000 to perform one or more features of the embodiments discussed herein. In various embodiments, the computer programs, when executed, enable the processor 1004 to perform the features of the above-described embodiments. Thus, such computer programs represent controllers of the computer system 1000.

[0090] The software may be stored in a computer program product and loaded into the computing system 1000 using the removable storage drive 1014, the hard disk drive 1012, or the interface 1020. Alternatively, the computer program product may be downloaded to the computer system 1000 via the communication path 1026. When executed by the processor 1004, the software causes the computing system 1000 to perform the functions of the embodiments described herein.

[0091] It should be understood that Figure 4 The embodiments of the present invention are given as examples only. Therefore, in some embodiments, one or more features of the computing system 1000 may be omitted. In addition, in some embodiments, one or more features of the computing system 1000 may be combined. In addition, in some embodiments, one or more features of the computing system 1000 may be separated into one or more components.

[0092] It should be understood that Figure 4 The illustrated elements are used to provide means for performing various functions and operations of the computer system described in the above embodiments.

[0093] The features disclosed in the preceding description, or in the following claims, or in the accompanying drawings, expressed in their specific form or as means for performing the disclosed functions, or as methods or processes for obtaining the disclosed results, may, where appropriate, be used alone or in any combination of these features to implement the invention in its different forms.

[0094] Although the present invention has been described in conjunction with the above exemplary embodiments, many equivalent modifications and variations will be apparent to those skilled in the art when this disclosure is given. Therefore, the above exemplary embodiments of the present invention are considered to be illustrative rather than restrictive. Various changes may be made to the described embodiments without departing from the spirit and scope of the present invention.

[0095] For the avoidance of any doubt, any theoretical explanations provided herein are intended to enhance the reader's understanding. The inventors do not wish to be bound by any of these theoretical explanations.

[0096] Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

[0097] Throughout the specification, including the following claims, unless the context requires otherwise, the words "comprise" and "comprising", and variations such as "comprises", "including" and "comprising", will be understood to imply the inclusion of stated integers or steps or integers or groups of steps but not the exclusion of any other integers or steps or integers or groups of steps.

[0098] It must be noted that, as used in the specification and the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from "about" one particular value, and / or to "about" another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when a value is expressed as an approximation by using the antecedent "about," it will be understood that the particular value forms another embodiment. The term "about" in relation to a numerical value is optional and means, for example, + / - 10%.

Claims

1. A system for quantifying the amount of re-breathed air inhaled by a person, the system comprising: a carbon dioxide sensor, which responds to carbon dioxide in the air; a heart rate sensor or a respiration rate sensor responsive to a person's heart rate or respiration rate, respectively; one or more processors, and one or more storage devices storing machine-readable instructions, wherein the machine-readable instructions are executable by the one or more processors to cause the processors to: Use the carbon dioxide sensor to measure the carbon dioxide concentration in the air. measuring the heart rate or breathing rate of a person using the heart rate sensor or the breathing rate sensor, respectively, and Instructs the execution of a computational operation to: Quantifying the amount of air a person breathes in based on measurements of their heart rate or breathing rate, Quantify the share of air that is re-breathed air based on the measurement of the CO2 concentration in the air, and Based on the quantified air quantity inhaled by the person and the quantified air portion of the rebreathed air, the air quantity of the rebreathed air inhaled by the person is quantified.

2. The system of claim 1, further comprising an accessory device for attaching one or more of the carbon dioxide sensor, the heart rate sensor, or the respiratory rate sensor to a person.

3. The system according to claim 1 or 2, wherein the system comprises a wireless communication interface, the wireless communication interface being used to interface with a wireless communication network, and the machine-readable instructions are executable by the one or more processors to cause the processor to output to the wireless communication network through the wireless communication interface: data representing measurements of a person's heart rate or breathing rate and measurements of the concentration of carbon dioxide in the air, and Instructions that perform computational operations.

4. The system of claim 1 or 2, wherein the machine-readable instructions are executable by one or more processors to cause the processors to perform computing operations.

5. The system of any one of the preceding claims, wherein the machine readable instructions are executable by the one or more processors to cause the one or more processors to output a representation of the quantified amount of air of the re-breathed air.

6. The system of any preceding claim, comprising an electronic display, wherein the machine readable instructions are executable by the one or more processors to cause the processor to display a visual representation of the quantified amount of air of the rebreathed air on the electronic display.

7. The system of any one of the preceding claims, wherein the machine-readable instructions are executable by the one or more processors to cause the processors to: using the carbon dioxide sensor and / or another sensor to measure atmospheric conditions and / or electromagnetic radiation, Determine whether the measured atmospheric conditions and / or electromagnetic radiation are greater than or less than a reference value, and In response to determining that the measured atmospheric conditions and / or electromagnetic radiation are greater than or less than one of the threshold values, continue to instruct execution of the computing operation, otherwise in response to determining that the measured atmospheric conditions and / or electromagnetic radiation are greater than or less than the other of the reference values, delay instructing execution of the computing operation.

8. A system according to any one of claims 1 to 6, wherein: The machine-readable instructions are executable by one or more processors to cause the processor to: using the carbon dioxide sensor and / or another sensor to measure atmospheric conditions and / or electromagnetic radiation, after a period of time has elapsed since the measurement of the atmospheric condition and / or the electromagnetic radiation, repeating the measurement of the atmospheric condition and / or the electromagnetic radiation using the carbon dioxide sensor and / or the further sensor, quantify the differences between measurements of atmospheric conditions and / or electromagnetic radiation and repeated measurements of atmospheric conditions and / or electromagnetic radiation, determining that a difference between a measurement of atmospheric conditions and / or electromagnetic radiation and a repeated measurement of atmospheric conditions and / or electromagnetic radiation is one of greater than or less than a threshold difference, and In response to determining that the difference is greater than or less than one of the threshold differences, continuing to instruct execution of the computing operation, otherwise in response to determining that the difference is greater than or less than the other of the threshold differences, delaying instructing execution of the computing operation.

9. A system according to any one of claims 1 to 6, wherein: the one or more storage devices storing data defining reference values, The machine-readable instructions are executable by one or more processors to cause the processor to: Determining whether the measured concentration of carbon dioxide in the air is greater than or less than a reference value; and In response to determining that the measured concentration of carbon dioxide in the air is greater than or less than one of the reference values, execution of the calculation operation is continued.

10. The system of claim 9, wherein the machine-readable instructions are executable by the one or more processors to cause the processors to: In response to determining that the measured concentration of carbon dioxide in the air is greater than or less than the other of the reference values, execution of the instruction calculation operation is delayed, and after a period of time has passed, the concentration of carbon dioxide in the air is repeatedly measured using the carbon dioxide sensor.

11. A system according to any of the preceding claims, wherein the machine-readable instructions are also executable by the one or more processors to cause the processor to instruct retrieval of data defining physiological characteristics of a person, and to quantify the amount of air inhaled by the person based on a measurement of the person's heart rate or breathing rate, including quantifying the amount of air inhaled by the person based on a measurement of the person's heart rate or breathing rate and the physiological characteristics.

12. The system of any one of the preceding claims, wherein the machine-readable instructions are executable by the one or more processors to cause the processors to: obtain an indication of the number of other people who are in the vicinity of the person; and Based on the measurement of the carbon dioxide concentration in the air by the carbon dioxide sensor and based on the indication of the number of other people in the vicinity, performance of a calculation operation is indicated to quantify the air fraction of re-breathed air.

13. A method for quantifying the amount of re-breathed air inhaled by a person, the method comprising: Use a carbon dioxide monitor to measure the concentration of carbon dioxide in the air to which a person is exposed, and Use a heart rate monitor or respiratory rate monitor to measure a person's heart rate or respiratory rate, The following quantification is indicated: Quantifying the amount of air inhaled by a person based on measurements of their heart rate or breathing rate, quantifying the air share of rebreathed air based on the measurement of the carbon dioxide concentration in the air by the carbon dioxide monitor, and The air quantity of the rebreathed air inhaled by the person is quantified based on the quantified air quantity inhaled by the person and the quantified air portion of the rebreathed air.

14. The method according to claim 13, further comprising: using the carbon dioxide monitor and / or another monitor to measure atmospheric conditions and / or electromagnetic radiation, Determine whether the measured atmospheric conditions and / or electromagnetic radiation are greater than or less than a reference value, and In response to determining that the measured atmospheric conditions and / or electromagnetic radiation are greater than or less than one of the thresholds, continuing to indicate quantization, otherwise in response to determining that the measured atmospheric conditions and / or electromagnetic radiation are greater than or less than the other of the thresholds, delaying indicating quantization.

15. The method according to claim 13, further comprising: using the carbon dioxide monitor and / or another monitor to measure atmospheric conditions and / or electromagnetic radiation, after a period of time has passed since the atmospheric conditions and / or electromagnetic radiation were measured, repeating the measurement of the atmospheric conditions and / or electromagnetic radiation using the carbon dioxide monitor and / or the additional monitor, determining whether a difference between a measurement of atmospheric conditions and / or electromagnetic radiation and a repeated measurement of atmospheric conditions and / or electromagnetic radiation is one of greater than or less than a threshold difference, and Indicating quantification is continued in response to determining that the difference is greater than or less than one of the threshold differences, and otherwise delayed in response to determining that the difference in measured atmospheric conditions and / or electromagnetic radiation is greater than or less than the other of the threshold differences.

16. The method according to claim 13, further comprising: Determine whether the measured concentration of carbon dioxide in the air is greater than or less than a reference value; and In response to determining that the measured concentration of carbon dioxide in the air is one of greater than or less than the reference value, execution of the calculation operation is continued.

17. The method according to claim 16, further comprising: In response to determining that the measured concentration of carbon dioxide in the air is greater than or less than the other of the reference values, the indication quantification is delayed, and after a period of time has elapsed, the concentration of carbon dioxide in the air is repeatedly measured using the carbon dioxide monitor.

18. The method according to any one of claims 13 to 17, further comprising: Instructing to retrieve data defining a physiological characteristic of the person, and instructing to quantify the amount of air inhaled by the person based on a measurement of the person's heart rate or breathing rate includes quantifying the amount of air inhaled by the person based on a measurement of the person's heart rate or breathing rate and the physiological characteristic.

19. The method according to any one of claims 13 to 18, further comprising: obtaining an indication of the number of other persons in the vicinity of the person; and The indication quantifies the air share that is re-breathed air based on the measurement of the carbon dioxide concentration in the air by the carbon dioxide monitor and based on an indication of the number of other people in the vicinity.

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