Method and device for evaluating exposure risk of indoor air microplastics

Abstract

The invention discloses a method for evaluating the exposure risk of indoor air micro-plastics. The method comprises the following steps: (1) acquiring indoor environment parameters and indoor micro-plastic parameters; (2) establishing an indoor air micro-plastic concentration evaluation model and a human body indoor air micro-plastic exposure risk evaluation model; and (3) coupling the indoor air micro-plastic concentration evaluation model and the human body indoor air micro-plastic exposure risk evaluation model, calculating an indoor air micro-plastic exposure risk grade index, and realizing indoor air micro-plastic exposure risk quantification. Through field identification and analysis of the device, the indoor air micro-plastic exposure risk grade index is directly calculated, and the indoor air micro-plastic exposure risk is rapidly evaluated.

Description

Technical Field

[0001] The present invention relates to the field of environmental governance, and in particular to a method and device for assessing the risk of exposure to microplastics in indoor air. Background Art

[0002] Currently, there are no dedicated equipment and standard methods for indoor air microplastic exposure risk assessment. Microplastic research is a relatively emerging field, especially in indoor air environments, where research is still in its early stages. Existing research mainly focuses on the detection, sources, and potential health impacts of microplastics, but a unified, standardized risk assessment method or framework has not yet been formed. Despite this, there are still some classic methods that can be used to assess the exposure risk of microplastics in indoor air, such as direct measurement. The direct measurement method uses professional instruments and equipment to monitor pollutant concentrations in real time or near real time or analyze them after sampling to obtain concentration-time distribution data of air pollutants ingested by personnel during their stay, which can be used to further calculate and evaluate exposure risks.

[0003] Traditional direct measurement methods rely on specialized sampling and analytical instruments and equipment, requiring laboratory analysis. While these methods offer advantages such as high accuracy, they also come with drawbacks such as complex instrumentation and high costs. Furthermore, for emerging pollutants such as airborne microplastics, online, real-time monitoring is currently not possible, requiring on-site sampling followed by laboratory analysis, which is time-consuming and inefficient. Summary of the Invention

[0004] Purpose of the invention: In order to solve the above problems, this application proposes a method and device for evaluating the risk of exposure to microplastics in indoor air. Through on-site identification and analysis by the device, the indoor air microplastic exposure risk level index is directly calculated, and the indoor air microplastic exposure risk is quickly assessed.

[0005] Technical solution: A method for assessing the risk of exposure to microplastics in indoor air, comprising the following steps:

[0006] (1) Collect indoor environmental parameters and indoor microplastic parameters;

[0007] (2) Establish a model for evaluating indoor air microplastic concentrations and a model for evaluating the risk of human exposure to indoor air microplastics;

[0008] (3) Couple the indoor air microplastic concentration assessment model and the human indoor air microplastic exposure risk assessment model to calculate the indoor air microplastic exposure risk level index and quantify the indoor air microplastic exposure risk.

[0009] Furthermore, the indoor environmental parameters include geometric characteristics and ventilation rate of the indoor space.

[0010] Furthermore, the indoor microplastic parameters include microplastic source intensity and air microplastic sedimentation rate.

[0011] Furthermore, the indoor air microplastic concentration evaluation model comprehensively considers indoor environmental parameters and indoor microplastic parameters and is constructed as follows:

[0012]

[0013] Wherein, C: indoor air microplastic concentration, t: time, S: air microplastic source intensity, V: indoor space volume, λ: ventilation rate, indicating the number of indoor air changes per hour, k: air microplastic deposition rate;

[0014] When the system reaches a steady state, When , formula (1) is simplified to:

[0015]

[0016] Formula (2) is the formula description of the indoor air microplastic concentration assessment model described in this scheme, indicating that the concentration of air microplastics is determined by the intensity of the microplastic source and the comprehensive removal rate of ventilation and sedimentation.

[0017] Furthermore, the air microplastic sedimentation rate k is calculated by combining the sedimentation rates of spherical microplastics and non-spherical microplastics, and the sedimentation rate of spherical microplastics is calculated using Stokes' law:

[0018]

[0019] Where, v: sedimentation velocity, ρ p : microplastic density, ρ a : air density, g: acceleration due to gravity, D: diameter of microplastics, μ: dynamic viscosity of air;

[0020] The sedimentation rate can be calculated based on the sedimentation velocity v:

[0021]

[0022] Where H is the microplastic suspension height;

[0023] For non-spherical microplastics, first calculate the equivalent aerodynamic diameter D eq , then substitute into formula (3) and formula (4) to calculate the equivalent aerodynamic diameter D eq The calculation is as follows:

[0024]

[0025] Among them, D eq: equivalent aerodynamic diameter of non-spherical microplastics; L: diameter of non-spherical microplastics; R: aspect ratio of non-spherical microplastics based on projected size;

[0026] The airborne microplastic sedimentation rate k is then calculated:

[0027] k=α k1+β k2 (6)

[0028] Among them, α: the proportion of spherical microplastics; β: the proportion of non-spherical microplastics; k1: the sedimentation rate of spherical microplastics; k2: the sedimentation rate of non-spherical microplastics.

[0029] Furthermore, the human indoor air microplastic exposure risk assessment model includes five risk factors: indoor air microplastic concentration C, human exposure time T, inhalation rate R, toxicity factor TF and particle size distribution D, which are described by the following formula:

[0030]

[0031] Among them, w i : The weight assignment of the i-th risk factor, γ i : the normalized score of the i-th risk factor;

[0032] γ i It is described by the following formula:

[0033]

[0034] Among them, X i : The actual measured value of the i-th indicator, X max : The reference maximum value of the i-th indicator, X min : The reference minimum value of the i-th indicator.

[0035] Furthermore, the indoor air microplastic exposure risk index RI is:

[0036]

[0037] When RI is [0-0.3), it is low risk; when RI is [0.3-0.6), it is medium risk; when RI is [0.6-1.0], it is medium risk.

[0038] A device for evaluating the risk of exposure to microplastics in indoor air, comprising a camera (1), a laser ranging sensor (2), a data storage and computing system (3), and a power supply system (4);

[0039] Indoor environmental parameters and indoor microplastic parameters are collected through a camera (1) and a laser ranging sensor (2);

[0040] The data storage and computing system (3) is used to establish an indoor air microplastic concentration assessment model and a human indoor air microplastic exposure risk assessment model; the indoor air microplastic concentration assessment model and the human indoor air microplastic exposure risk assessment model are coupled to calculate the indoor air microplastic exposure risk level index, thereby realizing the quantification of indoor air microplastic exposure risk.

[0041] Beneficial effects: This application can be used to quickly predict and evaluate the risk of indoor air microplastic exposure without relying on professional sampling, analysis and identification instruments and equipment, avoiding the problems of complex operation, high cost and low timeliness of the traditional "direct measurement method", while having high prediction and evaluation accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 Schematic diagram of the structure of a device for assessing the risk of exposure to microplastics in indoor air. DETAILED DESCRIPTION

[0043] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0044] Example 1:

[0045] A method for assessing the risk of exposure to microplastics in indoor air, comprising the following steps:

[0046] (1) Collect indoor environmental parameters and indoor microplastic parameters;

[0047] (2) Establish a model for evaluating indoor air microplastic concentrations and a model for evaluating the risk of human exposure to indoor air microplastics;

[0048] (3) Couple the indoor air microplastic concentration assessment model and the human indoor air microplastic exposure risk assessment model to calculate the indoor air microplastic exposure risk level index and quantify the indoor air microplastic exposure risk.

[0049] Furthermore, the indoor environmental parameters include the geometric characteristics of the indoor space and the ventilation rate. The geometric characteristics of the indoor space: the volume, height, and surface area of ​​the room will affect the distribution and concentration of microplastics. The ventilation rate (natural ventilation or mechanical ventilation) determines the degree of dilution and diffusion of microplastics.

[0050] Furthermore, the indoor microplastic parameters include microplastic source intensity and airborne microplastic settling rate. Indoor microplastics primarily originate from tiny particles released during use or aging from furniture, clothing, and plastic products. Microplastic source intensity is typically expressed as the number of microplastic particles released per hour. Microplastic particles gradually settle to the ground due to gravity, and the airborne microplastic settling rate is related to particle size, density, and other factors.

[0051] The main sources of microplastics in indoor environments include wearing synthetic fiber clothing, wear and tear of indoor furniture (such as carpets and sofas), and the use of plastic products. The release intensity varies depending on the source. It is also affected by transmission from outdoor sources. Measured data shows that wearing synthetic fiber clothing for 20 minutes of normal activity can release up to 400 fibrous microplastics per gram of clothing. Taking into account the frequency and intensity of human activities in real indoor scenes, the recommended range for the average release intensity can be set at 2000-3000 pieces / hour.

[0052] The settling rate of airborne microplastics is affected by their shape and size. Generally speaking, fibrous microplastics have greater air resistance than spherical microplastics and settle more slowly, while the settling behavior of flake-shaped microplastics is somewhere in between. Furthermore, larger microplastics settle faster, while smaller ones can remain suspended for extended periods.

[0053] Furthermore, the indoor air microplastic concentration evaluation model comprehensively considers indoor environmental parameters and indoor microplastic parameters and is constructed as follows:

[0054]

[0055] Wherein, C: indoor air microplastic concentration, t: time, S: air microplastic source intensity, V: indoor space volume, λ: ventilation rate, indicating the number of indoor air changes per hour, k: air microplastic deposition rate;

[0056] When the system reaches a steady state, When , formula (1) is simplified to:

[0057]

[0058] Formula (2) is the formula description of the indoor air microplastic concentration assessment model described in this scheme, indicating that the concentration of air microplastics is determined by the intensity of the microplastic source and the comprehensive removal rate of ventilation and sedimentation.

[0059] Ventilation rates are affected by many factors, including the type of ventilation system (e.g., natural ventilation versus mechanical ventilation), building design, space utilization, and indoor activities. They are also influenced by factors such as climatic conditions. Typical indoor space ventilation rates obtained from field measurements are shown in Table 1. In practice, appropriate values ​​can be selected based on specific circumstances and substituted into Formula (2) for calculation.

[0060] Table 1. Typical indoor environment ventilation rates

[0061]

[0062] Furthermore, the air microplastic sedimentation rate k is calculated by combining the sedimentation rates of spherical microplastics and non-spherical microplastics, and the sedimentation rate of spherical microplastics is calculated using Stokes' law:

[0063]

[0064] Where, v: sedimentation velocity, ρ p : microplastic density, ρ a : air density, g: acceleration due to gravity, D: diameter of microplastics, μ: dynamic viscosity of air;

[0065] The sedimentation rate can be calculated based on the sedimentation velocity v:

[0066]

[0067] Where H is the microplastic suspension height;

[0068] For non-spherical microplastics, first calculate the equivalent aerodynamic diameter D eq , then substitute into formula (3) and formula (4) to calculate the equivalent aerodynamic diameter D eq The calculation is as follows:

[0069]

[0070] Among them, D eq : equivalent aerodynamic diameter of non-spherical microplastics; L: diameter of non-spherical microplastics; R: aspect ratio of non-spherical microplastics based on projected size;

[0071] The airborne microplastic sedimentation rate k is then calculated:

[0072] k=α k1+β k2 (6)

[0073] Among them, α: the proportion of spherical microplastics; β: the proportion of non-spherical microplastics; k1: the sedimentation rate of spherical microplastics; k2: the sedimentation rate of non-spherical microplastics.

[0074] In practice, the revised microplastic sedimentation rate is first calculated using formulas (3) to (6), and then substituted into formula (2) to calculate the indoor air microplastic concentration. Each parameter can be calculated using measured data or by looking up Table 2 for quick calculation.

[0075] Table 2. Indoor air microplastic concentration model quick calculation query table

[0076]

[0077] Furthermore, the human indoor air microplastic exposure risk assessment model includes five risk factors: indoor air microplastic concentration C, human exposure time T, inhalation rate R, toxicity factor TF and particle size distribution D, which are described by the following formula:

[0078]

[0079] Among them, w i : The weight assignment of the i-th risk factor,

[0080] Currently, there is no reference for assigning weights to various indicators for respiratory exposure risk assessment of airborne microplastics, an emerging pollutant. This approach, based on the physicochemical properties of microplastics and their similarities to general airborne particulate matter in posing health risks, recommends the following weightings (Table 3). These weightings can be optimized and adjusted in practice as scientific research deepens.

[0081] Table 3. Weight distribution of each indicator

[0082] index Weight <![CDATA[Microplastic concentration w C > 0.25 <![CDATA[Exposure duration w T > 0.2 <![CDATA[Inhalation rate w R > 0.2 <![CDATA[Toxic factor w TF > 0.25 <![CDATA[Particle size distribution w D > 0.1

[0083] The weight distribution of each indicator satisfies the following formula:

[0084]

[0085] γ i : the normalized score of the i-th risk factor; γ i It is described by the following formula:

[0086]

[0087] Among them, X i : The actual measured value of the i-th indicator, X max : The reference maximum value of the i-th indicator, X min : The reference minimum value of the i-th indicator.

[0088] Based on the results of the literature review, the following reference values ​​are recommended as appropriate (Table 4). As scientific research deepens, the reference values ​​can be continuously optimized and adjusted in practice.

[0089] Table 4. Recommended reference values ​​for calculating normalized scores for each risk factor

[0090] Risk Factors symbol unit Reference minimum value Reference maximum value Air microplastic concentration C <![CDATA[per / m 3 > 0 10 Exposure duration T h / d 0 24 Inhalation rate R <![CDATA[m 3 / d]]> 4 29 Toxicity factors TF dimensionless 0.05 0.15 Particle size distribution D μm 0.1 500

[0091] Furthermore, the indoor air microplastic exposure risk index RI (Risk Index, RI) is:

[0092]

[0093] When RI is [0-0.3), it is low risk; when RI is [0.3-0.6), it is medium risk; when RI is [0.6-1.0], it is medium risk.

[0094] Example 2:

[0095] like Figure 1 As shown, the present invention provides a device for evaluating the risk of exposure to microplastics in indoor air, comprising a camera (1), a laser ranging sensor (2), a data storage and computing system (3), and a power supply system (4);

[0096] Indoor environmental parameters and indoor microplastic parameters are collected through a camera (1) and a laser ranging sensor (2);

[0097] The data storage and computing system (3) is used to establish an indoor air microplastic concentration assessment model and a human indoor air microplastic exposure risk assessment model; the indoor air microplastic concentration assessment model and the human indoor air microplastic exposure risk assessment model are coupled to calculate the indoor air microplastic exposure risk level index, thereby realizing the quantification of indoor air microplastic exposure risk.

[0098] The main working steps of this device are as follows:

[0099] ① Turn on and start the equipment;

[0100] ② Collect indoor environment pictures through the camera and its image sensor and perform picture recognition to analyze the types and abundance of microplastics in the indoor environment, providing measured values ​​for calculating the microplastic release intensity S;

[0101] ③ Use laser ranging sensors to measure room dimensions and provide measured values ​​for calculating the indoor space volume V;

[0102] ④ Combining the measured values ​​and the method described in this plan, calculate the indoor air microplastic concentration and the human exposure risk of indoor air microplastics in turn, and further analyze and define the indoor air microplastic exposure risk level.

[0103] ⑤ Complete on-site measurement, analysis and evaluation; output results and end work.

Claims

1. A method for assessing the risk of exposure to microplastics in indoor air, characterized in that: The following steps are involved: (1) Collect indoor environmental parameters and indoor microplastic parameters; (2) Establish a model for evaluating indoor air microplastic concentrations and a model for evaluating the risk of human exposure to indoor air microplastics; (3) Couple the indoor air microplastic concentration assessment model and the human indoor air microplastic exposure risk assessment model to calculate the indoor air microplastic exposure risk level index and quantify the indoor air microplastic exposure risk.

2. A method for assessing the risk of indoor air microplastic exposure according to claim 1, characterized in that: The indoor environmental parameters include geometric characteristics and ventilation rate of the indoor space.

3. The method for assessing the risk of indoor air microplastic exposure according to claim 1, characterized in that: The indoor microplastic parameters include microplastic source intensity and air microplastic sedimentation rate.

4. A method for assessing the risk of indoor air microplastic exposure according to claim 1, characterized in that: The indoor air microplastic concentration evaluation model comprehensively considers indoor environmental parameters and indoor microplastic parameters and is constructed as follows: Wherein, C: indoor air microplastic concentration, t: time, S: air microplastic source intensity, V: indoor space volume, λ: ventilation rate, indicating the number of indoor air changes per hour, k: air microplastic deposition rate; When the system reaches a steady state, When , formula (1) is simplified to: Formula (2) is the formula description of the indoor air microplastic concentration assessment model described in this scheme, indicating that the concentration of air microplastics is determined by the intensity of the microplastic source and the comprehensive removal rate of ventilation and sedimentation.

5. A method for assessing the risk of indoor air microplastic exposure according to claim 4, characterized in that: The air microplastic sedimentation rate k is a combination of the sedimentation rates of spherical microplastics and non-spherical microplastics. The sedimentation rate of spherical microplastics is calculated using Stokes' law: Where, v: sedimentation velocity, ρ p : microplastic density, ρ a : air density, g: acceleration due to gravity, D: diameter of microplastics, μ: dynamic viscosity of air; The sedimentation rate can be calculated based on the sedimentation velocity v: Where H is the microplastic suspension height; For non-spherical microplastics, first calculate the equivalent aerodynamic diameter D eq , then substitute into formula (3) and formula (4) to calculate the equivalent aerodynamic diameter D eq The calculation is as follows: Among them, D eq : equivalent aerodynamic diameter of non-spherical microplastics; L: diameter of non-spherical microplastics; R: aspect ratio of non-spherical microplastics based on projected size; The airborne microplastic sedimentation rate k is then calculated: k=α k1+β k2 (6) Among them, α: the proportion of spherical microplastics; β: the proportion of non-spherical microplastics; k1: the sedimentation rate of spherical microplastics; k2: the sedimentation rate of non-spherical microplastics.

6. The method for assessing the risk of indoor air microplastic exposure according to claim 1, characterized in that: The human indoor air microplastic exposure risk assessment model includes five risk factors: indoor air microplastic concentration C, human exposure time T, inhalation rate R, toxicity factor TF and particle size distribution D, which are described by the following formula: Among them, w i : The weight assignment of the i-th risk factor, γ i : the normalized score of the i-th risk factor; γ i It is described by the following formula: Among them, X i : The actual measured value of the i-th indicator, X max : The reference maximum value of the i-th indicator, X min : The reference minimum value of the i-th indicator.

7. The method for assessing the risk of indoor air microplastic exposure according to claim 1, characterized in that: The indoor air microplastic exposure risk index RI is: When RI is [0-0.3), it is low risk; when RI is [0.3-0.6), it is medium risk; when RI is [0.6-1.0], it is medium risk.

8. A device for assessing the risk of exposure to microplastics in indoor air, characterized in that: It includes a camera (1), a laser ranging sensor (2), a data storage and computing system (3) and a power supply system (4); Indoor environmental parameters and indoor microplastic parameters are collected through a camera (1) and a laser ranging sensor (2); Using the data storage and computing system (3), establish an indoor air microplastic concentration assessment model and a human indoor air microplastic exposure risk assessment model; By coupling the indoor air microplastic concentration assessment model and the human indoor air microplastic exposure risk assessment model, the indoor air microplastic exposure risk level index is calculated to quantify the indoor air microplastic exposure risk.

9. The device for assessing the risk of exposure to microplastics in indoor air according to claim 8, characterized in that: The indoor air microplastic concentration evaluation model comprehensively considers indoor environmental parameters and indoor microplastic parameters and is constructed as follows: Wherein, C: indoor air microplastic concentration, t: time, S: air microplastic source intensity, V: indoor space volume, λ: ventilation rate, indicating the number of indoor air changes per hour, k: air microplastic deposition rate; When the system reaches a steady state, When , formula (1) is simplified to: Formula (2) is the formula description of the indoor air microplastic concentration assessment model described in this scheme, indicating that the concentration of air microplastics is determined by the intensity of the microplastic source and the comprehensive removal rate of ventilation and sedimentation.

10. The device for assessing the risk of exposure to microplastics in indoor air according to claim 8, characterized in that: The human indoor air microplastic exposure risk assessment model includes five risk factors: indoor air microplastic concentration C, human exposure time T, inhalation rate R, toxicity factor TF and particle size distribution D, which are described by the following formula: Among them, w i : The weight assignment of the i-th risk factor, γ i : the normalized score of the i-th risk factor; γ i It is described by the following formula: Among them, X i : The actual measured value of the i-th indicator, X max : The reference maximum value of the i-th indicator, X min : The reference minimum value of the i-th indicator.

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