POLLUTION DETECTION STAMP

Abstract

POLLUTION DETECTION STAMP The invention relates to articles, apparatus, and methods for determining and measuring exposure to environmental particulate matter. A pollution detection stamp implements a polymer that becomes dark or discolored due to the adhesion of airborne particulate matter to the polymer, and a discoloration reference for an optical or visual correlation of the degree of discoloration of the polymer with a known level of exposure to environmental particulate matter associated with the discoloration reference. The pollution detection stamp can be used as a standalone article to monitor exposure or can be incorporated into other articles, products, devices, or environments for low-maintenance monitoring of exposure to environmental particulate matter. Figure for abstract: none

Description

Title of the invention: POLLUTION DETECTION STAMP SUMMARY

[0001] In one aspect, the disclosure provides an article for determining exposure to airborne particulate matter, the article comprising: a polymer configured to adsorb airborne particles thereon, wherein adsorption of airborne particles to the polymer causes the polymer to transform into a decolorized polymer; and a decolorization reference configured for optical comparison with the decolorized polymer, wherein the optical comparison allows determination of whether the article has been exposed to airborne particulate matter.

[0002] In embodiments, the discoloration reference optically matches the discolored polymer, such that a visual appearance of the discoloration reference at least partially matches a visual appearance of the discolored polymer for determining whether the article is exposed to airborne particulate matter.

[0003] In some embodiments, the polymer is hydrophobic.

[0004] In embodiments, the discoloration reference is movably attached to a portion of the article that includes the polymer on at least a portion thereof, such that movement of the discoloration reference toward or relative to the polymer facilitates optical comparison.

[0005] In embodiments, the discoloration reference is rotatably attached to a portion of the article that includes the polymer on at least a portion thereof, such that rotational movement of the discoloration reference toward or relative to the polymer facilitates optical comparison.

[0006] In embodiments, the discoloration reference includes an aperture therein, such that a portion of a surface positioned below the aperture appears adjacent to the discoloration reference for optical comparison between the discoloration reference and the discolored polymer.

[0007] In embodiments, the article comprises a plurality of discoloration references along a gradient and each discoloration reference corresponds to a degree of discoloration of the discolored polymer.

[0008] In embodiments, the article further comprises an attachment portion configured to attach the article to a surface.

[0009] In embodiments, the attachment portion is a lower layer of the article, the polymer is at least part of an intermediate layer of the article, and the discoloration reference is an upper layer of the article.

[0010] In one aspect, the disclosure provides an article for measuring exposure to airborne particulate matter, the article comprising: a polymer configured to adsorb airborne particles thereon, wherein adsorption of airborne particles to the polymer causes the polymer to transform into a decolorized polymer that is decolorized with a degree of decolorization; and a plurality of decolorization references along a gradient configured for optical comparison with the decolorized polymer, wherein the optical comparison correlates a particular decolorization reference of the gradient with the degree of decolorization of the decolorized polymer for measuring exposure of the article to airborne particulate matter.

[0011] In embodiments, each discoloration reference corresponds to a level of exposure to airborne particulate matter that is based at least in part on a concentration of airborne particulate matter in an environment.

[0012] In embodiments, the plurality of fading references are arranged adjacent to each other in an arrangement where the gradient increases along the arrangement.

[0013] In embodiments, the article is circular, the arrangement of the plurality of discoloration references is a semicircle, and each discoloration reference is a sector of the semicircle.

[0014] In embodiments, each discoloration reference includes an aperture thereon, such that a portion of a surface positioned below the aperture appears adjacent to the particular discoloration reference for optical comparison between the particular discoloration reference and the degree of discoloration of the discolored polymer.

[0015] In embodiments, the semicircular arrangement of the plurality of discoloration references is rotatably attached to a portion of the article that includes the polymer on at least a portion thereof, such that rotational movement of the semicircular arrangement of the plurality of discoloration references toward or relative to the polymer facilitates optical comparison.

[0016] This summary is provided to present a selection of concepts in simplified form which are described more fully below in the detailed description. This summary is not intended to identify key features of the claimed subject matter nor to be used as an aid in determining the scope of the claimed subject matter. Description of the Drawings

[0017] [Fig.l] [Fig.l] shows an exploded perspective view of an exemplary pollution detection patch, according to the disclosure.

[0018] [Fig.2] [Fig.2] shows a top view of the exemplary pollution detection patch, not exposed to particulate pollution.

[0019] [Fig.3] [Fig.3] shows a top view of the exemplary pollution detection patch, after exposure to a degree of particulate pollution such that a polymer of the patch is discolored.

[0020] [Fig.4] [Fig.4] shows a top view of the exemplary pollution detection patch, after exposure to particulate pollution, with a discoloration reference configured for optical comparison rotated for comparison with the discolored polymer.

[0021] [Fig.5] [Fig.5] shows a flowchart of steps of an exemplary method of mitigating risk due to exposure to particulate matter using an exemplary pollution detection patch according to the disclosure.

[0022] The foregoing aspects and numerous associated advantages of the present invention will be more readily appreciated as they are better understood with reference to the following detailed description, when taken in conjunction with the accompanying drawings. Detailed description

[0023] Particulate pollution or particulate matter (PM) is composed of particles of solids and / or liquids that are in the air. Examples include dust, dirt, soot, smoke, and liquid droplets. This type of pollution can come from primary sources that form particles on their own, such as wood stoves and forest fires, as well as from secondary sources that emit gases that, in turn, form particles, such as power plants, coal fires, factories, vehicles, and the like. Often, these emissions contain PM in the form of fine particles (e.g., PM2.5) and / or coarse particles (e.g., PM10). Fine particles (e.g., PM2.5) can be considered particularly hazardous to health because they can penetrate the skin, lungs, blood, and / or other organs and cause health problems.In particular, exposure to PM2.5 has been associated with ischemic heart disease, stroke, COPD, diabetes mellitus, and lung cancer (Sang, S. et al. The global burden of disease attributable to ambient fine particulate matter in 204 countries and territories, 1990-2019: A systematic analysis of the Global Burden of Disease Study 2019. Ecotoxicol Environ Saf. 15 Jun 2022;238:113588.).

[0024] Typical MP monitoring devices are complex and employ a wide range of dedicated electronic features for analysis. There is a need for devices that require little or no power to operate, that can be reliably implemented in a consumer or industrial setting for monitoring PM exposure over longer periods. The present disclosure addresses these and other long-unmet needs in the art. POLLUTION DETECTION STAMPS

[0025] In one aspect, the disclosure provides an article, e.g., a pollution detection patch, for determining exposure to airborne particulate matter. The article may be operable to monitor exposure to airborne particulate matter without having a wide range of dedicated electronic functionality. The article may include a polymer, e.g., a hydrophobic polymer, that adsorbs airborne particles onto it, causing discoloration of the polymer due to adsorption of the particulate matter onto the polymer. The article may further include a discoloration reference that contains one or more reference values ​​for optically comparing the degree of discoloration of the polymer with the reference.This optical comparison allows the determination of whether or not the article is exposed to particulate matter suspended in the air and, if so, to what degree.

[0026] In embodiments, the article is for a binary determination of whether the article is exposed to PM in an environment (i.e., PM exposure TRUE or FALSE). However, in some embodiments, the article may be discolored according to a degree of discoloration, and a plurality of discoloration references, e.g., along a gradient, are configured for optical comparison with the discolored polymer. In such embodiments, the optical comparison correlates a particular discoloration reference of the gradient with the degree of discoloration of the discolored polymer for measurement of an exposure of the article to airborne particulate matter.

[0027] By way of example, [Fig. 1] shows an exemplary pollution detection patch, according to the disclosure, in an exploded perspective view. In the embodiment shown, a pollution detection patch 1 includes a plurality of discoloration references 2 (i.e., is composed of individual discoloration references 5, 6, 7, 8) along a gradient, such that each discoloration reference corresponds to a degree of discoloration of the discolored polymer. For example, reference 5 corresponds to no or negligible exposure to PM; reference 6 corresponds to light exposure; reference 7 corresponds to intermediate exposure; and reference 8 corresponds to heavy exposure. The shade of the reference increases in opacity or darkness as the exposure levels increase. corresponding are higher. In the embodiment shown, the article 1 is circular, and the arrangement of the plurality of discoloration references 2 is a semicircle, and each discoloration reference (5, 6, 7, 8) is a sector of the semicircle. However, other article shapes and other arrangements of the plurality of discoloration references 2 may be implemented, according to embodiments. In embodiments, the plurality of discoloration references 2 may be laminated with a transparent polymer film or glass, for example.

[0028] In the embodiment shown, the plurality of discoloration references 2 are arranged on a semicircular piece of suitable material, such as fabric, paper, polymer, plastic, wood, metal or any combination thereof, or other suitable material; however, other shapes and / or materials may be implemented, in embodiments. In the embodiment shown, the plurality of discoloration references 2 are arranged so that the references are adjacent to each other in an arrangement where the gradient increases along the arrangement, however, the references (5, 6, 7, 8) may be arranged in any arrangement.In the embodiment shown, each reference (5, 6, 7, 8) contains an aperture (5a, 6a, 7a, 8a) therethrough, such that surfaces positioned below the aperture are visible when viewed from above the article, as explained elsewhere herein. In this manner, the references (5, 6, 7, 8) are more easily compared visually or optically with the polymer for determination of an exposure level.

[0029] In the embodiment shown, the patch 1 comprises a polymer layer 3, composed of an inert support 10 and a polymer 11; in embodiments, the inert support 10 is coated with a dispersion of a pollutant-attracting polymer, as described elsewhere herein. The inert support 10 may be non-reactive with MP, however, the polymer 11 is reactive with MP in the sense that it adsorbs MP thereon, resulting in discoloration of the polymer 11 and functionality of the patch in detecting and / or quantifying airborne MP exposure levels in the environment. In some embodiments, the polymer 11 is deposited on one half of a circular disc-shaped inert support 10, such that half of the inert support 10 does not have the polymer thereon, and the other half of the inert support 11 does have the polymer thereon.However, in some embodiments, a larger portion of the inert support 10, e.g., all of the inert support 10, may receive the polymer 11 deposited thereon to completely cover the upper surface of the polymer layer 3 with the polymer 11.

[0030] In the embodiment shown, the article 1 further comprises an attachment portion 4 configured for attachment of the article 1 to a surface. The attachment portion 4 may include, for example, an adhesive tape, a magnetic layer for attaching the stamp to metal surfaces such as cars or the like, a hook-and-loop fastener, or other structure on a bottom of the attachment portion 4. The attachment portion 4 may include an adhesive 12 on a top of the attachment portion 4 for attaching the polymer layer 3 thereto.

[0031] In some embodiments, the attachment portion 4 may be configured to suspend the article 1 from a surface or other article, or from a body of an individual who is wearing the article 1. In cases where a person is wearing the article 1, the article 1 may function as a type of “dosimeter” to monitor the person’s exposure to PM. This wearable “exposome monitor” may monitor individual exposure and serve as an early warning system for potentially harmful exposure levels, allowing the individual to mitigate their exposure to potentially harmful pollution (e.g., “exposome”) by adjusting their location, behavior, or routine, or by implementing other protective actions such as applying protective materials, substances, or personal protective equipment (PPE) to protect the individual from potential health problems due to PM exposure.In exemplary embodiments, the patch may be used as an indicator of when and / or where respirators and / or eye or other protection should be worn, for example. In some embodiments, the patch itself may be used as an indicator of when and / or where a filter, such as a respirator or other PM filter, is worn or clogged and needs to be serviced, cleaned, or replaced; for example, the patch 1 may be attached to or integrated with a respirator, such as an N95 respirator, or the like. Additionally, in industrial environments, for example, the accumulation of airborne PM may be an indicator of actual or potential equipment failure; in such cases, the patch 1 may be used to warn operators of impending equipment failure or a need for maintenance.

[0032] In the embodiment shown, a central hinge is comprised of an upper pin 9a, which extends through the polymer pinhole 9b and the attachment portion pinhole 9c to secure the plurality of discoloration references 2 to the polymer layer 3 and the attachment portion 4 to form an assembled state of the article 1 for use. The central hinge (91, 9b, 9c) allows rotation of the plurality of discoloration references 2 relative to the polymer layer 3, as described elsewhere herein, for easier visual comparison of the references (5, 6, 7, 8) with the polymer discoloration 11.

[0033] In embodiments, the references of the plurality of discoloration references (5, 6, 7, 8) correspond to qualitative levels of exposure to MP. For example, in at least some situations, it may be sufficient for the level of exposure to MP to be indicated as "mild," "intermediate," or "significant," as appropriate. However, in other situations, the plurality of discoloration references 2 (i.e., 5, 6, 7, 8) correspond to defined quantitative exposure levels to MP. An example of a defined exposure level may include exposure to a particular concentration of airborne MP, optionally for a particular period of time. In embodiments, the plurality of discoloration references may be selected or calibrated based on the performance of a particular polymer over a range of defined quantitative exposure levels to MP.In this manner, the coloration or hue of a given discolored polymer state can be matched to a particular reference for the determination of at least an approximate exposure level as indicated by that reference. For example, suppose that reference 6 corresponds to a particulate matter exposure quantification of X. If the polymer of the article discolors such that it at least approximately resembles reference 6, then it can be said that a particulate matter exposure quantification in one or more environments in which the article is placed is at least approximately X. In this manner, the article can be configured for qualitative use and / or quantitative use, and can be used in any of a variety of scenarios, including personal use, industrial use, and others.

[0034] Referring now to [Fig. 2] which shows a top view of the exemplary pollution detection patch 1 in the assembled state and not exposed to particulate pollution. The polymer is in an undiscolored state 11a, and optically corresponds to reference 5, i.e., negative control reference. In the embodiment shown, the undiscolored state 11a of the polymer is bright white. As shown in [Fig. 3], after exposure to a degree of particulate pollution such that a polymer of the patch is discolored, the polymer is in a discolored state 11b. In the embodiment shown, the discolored state 11b optically corresponds to the reference 6, such that a visual appearance of the discoloration reference 6 at least partially matches a visual appearance of the discolored polymer 11b for determining whether the article is exposed to airborne particulate matter, and if so, to what degree.

[0035] Referring now to [Fig. 4] which shows a top view of the exemplary pollution detection patch 1 after exposure to particulate pollution, with a discoloration reference 6 configured for optical comparison moved or rotated for comparison with the discolored polymer 11b. In the embodiment shown, the plurality of discoloration references (5, 6, 7, 8) are rotated by 90 degrees such that the bleaching reference 6 overlaps the polymer when the polymer is in the bleached state 11b. In this configuration, the bleached state 11b is visible through the aperture of the reference 6, for easier visual comparison of the reference 6 with the bleached state 11b. In the example shown, the bleached state 11b at least approximately corresponds to the reference 6, e.g., based on coloration and / or grayscale tone, brightness, chromaticity and / or saturation, e.g., The bleached state 11b, and other bleached states of the polymer, may appear as decreases in brightness from the default coloration to bright white, e.g. The determined exposure may be graded, for example, as a score of 1 to 10, where 1 is less than and 10 is greater than exposure to PM, according to embodiments.

[0036] In some embodiments, the pollution detection patch may be implemented as, or incorporated into, any form factor as desired. Exemplary form factors include a disposable patch, a reusable patch, a washable patch, a bracelet, a ring, a necklace, or another wearable form factor. In some embodiments, the patch may be attached to a vehicle, a home, or other structure, equipment monitoring systems, manufacturing or machining systems, and the like.

[0037] In some embodiments, the polymer used to make the patch is hydrophobic and can attract airborne pollution such as dust, carbon soot, PM2.5, and the like. In exemplary embodiments, a polymer produced by MYCELX® may be used as the polymer of a patch or article of the disclosure, however, any suitable polymer or other material may be used depending on its effectiveness. Exemplary MYCELX® polymer compositions for making a polymer of a patch or article of the disclosure may include, by way of non-limiting examples, one or more compositions or polymers disclosed in U.S. Patent No. 5,746,925, one or more compositions or polymers disclosed in U.S. Patent No. 5,437,793, and / or one or more compositions or polymers disclosed in U.S. Patent No. 5,698,139.

[0038] In some embodiments, a polymer composition of the disclosure may be produced by chemically reacting (e.g., crosslinking) linseed oil with isobutyl methacrylate, and diluting the product with a suitable solvent, such as 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate. The composition formed by the thermal reaction of linseed oil with the isobutyl methacrylate polymer is a flexible resinous product that, when diluted with the solvent, results in a mixture that can be sprayed onto a surface, such as the inert support 10 of the stamp of the disclosure. In some embodiments, a polymer of the article of the disclosure may be produced from methacrylate polymers and any of a variety of naturally occurring animal and vegetable oils. The oil and polymer may be reacted in a thermal reaction that appears to be insensitive to the atmosphere under which the reaction is carried out, i.e., whether it is an inert, oxidizing, or reducing atmosphere. Compositions having an oil to polymer ratio ranging from about 3:1 to 1:1 may be used, resulting in polymers having physical properties ranging from soft to hard, and from elastomeric to brittle in nature depending on the oil to polymer ratio and the choice of polymer and / or oil used.

[0039] In embodiments, a polymer composition may be applied to the inert support 10 by reducing the viscosity of the polymer composition and depositing it on the inert support 10, which may be porous, in embodiments. Since the viscosity of MYCELX® polymer compositions at room temperature is very high (e.g., about 700 to 800 pa*s), in embodiments, a method of depositing a polymer composition on an inert support 10 includes reducing the viscosity of a polymer composition by heating, or dissolving in a solution, and then depositing the reduced-viscosity polymer composition on an inert support 10.

[0040] As a first example of depositing a polymer composition onto an inert support 10, a first step includes mixing the polymer composition into a caprylic / capric triglyceride at any concentration, from 0 to 100% to produce a polymer composition mixture; a second step includes immersing the stamp (e.g., the inert support 10, which may include cellulose, for example) into the polymer composition mixture for 30 minutes; and a third step includes removing the inert support 10 from the polymer composition mixture and drying the inert support 10, optionally at an elevated temperature, for a period of time (e.g., overnight).

[0041] As a second example of depositing a polymer composition onto an inert support 10, a first step includes mixing the polymer composition into isododecane at any concentration, from 0 to 100%, preferably from 20 to 100%, to produce a polymer composition mixture; a second step includes immersing the stamp (e.g., the inert support 10, which may include cellulose, for example) into the polymer composition mixture for 30 minutes; and a third step includes removing the inert support 10 from the polymer composition mixture and drying the inert support 10, optionally at an elevated temperature, for a period of time (e.g., overnight). NECESSARIES AND PROCESSES

[0042] In other aspects, the disclosure provides kits that include one or more patches of the disclosure. Exemplary embodiments of kits include a pollution detection patch, optionally in combination with instructional materials, for example. The kits may be provided and / or used as stand-alone units, or may be combined with other products or kits for combination offerings. An exemplary combination kit includes one or more pollution detection patches and one or more skin care products, for example, to alleviate adverse skin health issues that might result from exposure to pollution or PM, for example.

[0043] In other aspects, the disclosure provides methods of managing or mitigating risk due to exposure to PM, optionally in combination with one or more other pollutants or environmental stressors. As shown in [Fig. 5], an exemplary method 13 of mitigating risk due to exposure to particulate matter may utilize an exemplary pollution detection patch according to the disclosure. In the embodiment shown, the method 13 of mitigating risk comprises step 14: providing a pollution detection patch, wherein a patch is provided to a person, group of persons, or organization. In step 15, which may be optional, the pollution detection patch may be docked to a surface. In step 16, the pollution detection patch is exposed to particulate pollution, resulting in discoloration of the polymer of the patch, as described elsewhere herein.In step 17, a reference is compared to the discoloration of the polymer, i.e., the particle-reactive portion of the patch, for comparison. In step 18, the level of exposure to PM is determined based on the comparison. In step 19, the exposome—the range of potentially harmful environmental exposures to which a person or group of individuals is exposed (including exposure to PM)—is adjusted so that the person or group of individuals has a lower risk of adverse health outcomes due to their exposome. Examples of adjustments may include changing a travel or transportation route, staying indoors for a specified amount of time, wearing a respirator, applying a cosmetic composition to the skin or other part of the body, taking medication, or taking some other action. NON-LIMITING EMBODIMENTS

[0044] Although general features of the disclosure are described and shown and particular features of the disclosure are set forth in the claims, the following non-limiting embodiments relate to features, and combinations of features, which are explicitly contemplated as part of the disclosure. The non-limiting embodiments The following limiting embodiments contain elements that are modular and may be combined with each other in any number, order, or combination to form a new non-limiting embodiment, which may itself be combined with other non-limiting embodiments.

[0045] Embodiment 1. An article for determining exposure to airborne particulate matter, the article comprising: a polymer configured to adsorb airborne particles thereon, wherein adsorption of airborne particles to the polymer causes the polymer to transform into a decolorized polymer; and a decolorization reference configured for optical comparison with the decolorized polymer, wherein the optical comparison enables determination of whether the article has been exposed to airborne particulate matter.

[0046] Embodiment 2. An article of any other embodiment, wherein the discoloration reference optically matches the discolored polymer, such that a visual appearance of the discoloration reference at least partially matches a visual appearance of the discolored polymer for determining whether the article is exposed to airborne particulate matter.

[0047] Embodiment 3. Article of any other embodiment, wherein the polymer is hydrophobic.

[0048] Embodiment 4. An article of any other embodiment, wherein the discoloration reference is movably attached to a portion of the article that includes the polymer over at least a portion thereof, such that movement of the discoloration reference toward or relative to the polymer facilitates optical comparison.

[0049] Embodiment 5. An article of any other embodiment, wherein the discoloration reference is rotatably attached to a portion of the article that includes the polymer on at least a portion thereof, such that rotational movement of the discoloration reference toward or relative to the polymer facilitates optical comparison.

[0050] Embodiment 6. An article of any other embodiment, wherein the discoloration reference includes an aperture thereon, such that a portion of a surface positioned below the aperture appears adjacent to the discoloration reference for optical comparison between the discoloration reference and the discolored polymer.

[0051] Embodiment 7. An article of any other embodiment, wherein the article comprises a plurality of discoloration references along a gradient and each discoloration reference corresponds to a degree of discoloration of the discolored polymer.

[0052] Embodiment 8. An article of any other embodiment, wherein the article further comprises an attachment portion configured for attachment of the article to a surface.

[0053] Embodiment 9. An article of any other embodiment, wherein the attachment portion is a lower layer of the article, the polymer is at least part of an intermediate layer of the article, and the discoloration reference is an upper layer of the article.

[0054] Embodiment 10. An article for measuring exposure to airborne particulate matter, the article comprising: a polymer configured to adsorb airborne particles thereon, wherein adsorption of airborne particles to the polymer causes the polymer to transform into a decolorized polymer that is decolorized with a degree of decolorization; and a plurality of decolorization references along a gradient configured for optical comparison with the decolorized polymer, wherein the optical comparison correlates a particular decolorization reference of the gradient with the degree of decolorization of the decolorized polymer for measuring exposure of the article to airborne particulate matter.

[0055] Embodiment 11. An article of any other embodiment, wherein each discoloration reference corresponds to a level of exposure to airborne particulate matter that is based at least in part on a concentration of airborne particulate matter in an environment.

[0056] Embodiment 12. Article of any other embodiment, wherein the plurality of discoloration references are arranged adjacent to each other in an arrangement where the gradient increases along the arrangement.

[0057] Embodiment 13. An article of any other embodiment, wherein the article is circular, the arrangement of the plurality of discoloration references is a semicircle, and each discoloration reference is a sector of the semicircle.

[0058] Embodiment 14. An article of any other embodiment, wherein each discoloration reference includes an aperture thereon, such that a portion of a surface positioned below the aperture appears adjacent to the particular discoloration reference for optical comparison between the particular discoloration reference and the degree of discoloration of the discolored polymer.

[0059] Embodiment 15. An article of any other embodiment, wherein the semicircular arrangement of the plurality of discoloration references is rotatably attached to a portion of the article that includes the polymer on at least a portion thereof, such that rotational movement of the semicircular arrangement of the plurality of discoloration references toward or relative to the polymer facilitates optical comparison.

[0060] Although illustrative embodiments have been illustrated and described, it will be appreciated that various changes may be made therein without departing from the spirit and scope of the disclosure.

Claims

Claims

1. Article (1) for determining exposure to airborne particulate matter, the article comprising: - a polymer (11) configured to adsorb airborne particles thereon, wherein adsorption of airborne particles onto the polymer causes the polymer to transform into a discolored polymer; and - a discoloration reference (2, 5, 6, 7, 8) configured for optical comparison with the discolored polymer, wherein the optical comparison allows determination of whether the article is exposed to airborne particulate matter.

2. An article according to claim 1, wherein the polymer (11) is hydrophobic.

3. The article of claim 1, wherein the discoloration reference (2) is movably attached to a portion of the article that comprises the polymer on at least a portion thereof, such that movement of the discoloration reference toward or relative to the polymer facilitates optical comparison.

4. The article of claim 1, wherein the discoloration reference (2) is rotatably attached to a portion of the article that comprises the polymer on at least a portion thereof, such that rotational movement of the discoloration reference toward or relative to the polymer facilitates optical comparison.

5. The article of claim 1, wherein the discoloration reference (2) comprises an opening thereon, such that a portion of a surface positioned below the opening appears adjacent to the discoloration reference for optical comparison between the discoloration reference and the discolored polymer.

6. The article of claim 1, wherein the article comprises a plurality of discoloration references (2, 5, 6, 7, 8) along a gradient and each discoloration reference corresponds to a degree of discoloration of the discolored polymer.

7. The article of claim 1, wherein the article further comprises an attachment portion (4) configured for attachment of the article to a surface.

8. An article according to claim 7, wherein the fixing portion (4) is a lower layer of the article, the polymer is at least part of an intermediate layer of the article, and the discoloration reference is an upper layer of the article.