1、CEN ENx48L 93 = 340Y589 0049056 930 EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 481 July 1993 UDC 628.511 : 331.1 : 620.113 Descriptors: Air, quality, air pollution, workroom, accident prevention, aerosols, sampling, suspended matter, measurements, particle density : concentration, specific
2、ations English version Workplace atmospheres - Size fraction definitions for measurement of airborne particles Atmosphres des lieux de travail - Dfinition des fractions de taille pour le mesurage des particules en suspension dans lair Arbeitsplatzatmosphre - Feslegung der Teilchengrfienverteilung zu
3、r Messung luftgetragener Partikel This European Standard was approved by CEN on 1993-07-27. CEN members are bound to comply with the CENKENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date l
4、ists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the res
5、ponsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norw
6、ay, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels O 1993 Copyright reserved to CEN members Ref. No. EN 481 : 1993 E CEN ENJ48L
7、93 = 3404589 0049057 877 Page 2 EN 481: 1993 Foreword This European Standard was drawn up by Technical Committee 137 Assessment of workplace exposure of which the secretariat is held by DIN. This standard was submitted for Formal Vote, and the result was positive. This European Standard shall be giv
8、en the status of a national standard, either by publication of an identical text or by endorsement, at the latest by January 1994, and conflicting national standards shall be withdrawn at the latest by January 1994. According to the CENKENELEC Internal Regulations, the following countries are bound
9、to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, United Kingdom. CEN ENS481 93 = 3404589 0049058 703 = O Introduction The proportion of total particulate m
10、atter which is inhaled into a human body depends on properties of the particles, on the speed and direction of air movement near the body, on breathing rate, and whether breathing is through nose or mouth. Inhaled particles can then deposit somewhere in the respiratory tract, or can be exhaled. The
11、site of deposition, or probability of exhalation, depends on properties of the particle, respiratory tract, breathing pattern, and other factors. Liquid particles or soluble components of solid particles can be absorbed by the tissues wherever they deposit. Particles can cause damage close to the de
12、position site if they are corrosive, radioactive, or capable of initiating some other type of damage. Insoluble particles can be transported to another part of the respiratory tract or body, where they can be absorbed or cause a biological effect. There is a wide variation from one person to another
13、 in the probability of particle inhalation, deposition, reaction to deposition, and clearance. Nevertheless, it is possible to define conventions for size selective sampling of airborne particles when the purpose of sampling is health-related. These conventions are relationships between aerodynamic
14、diameter and the fractions to be collected or measured, which approximate to the fractions penetrating to regions of the respiratory tract under average conditions. Measurement conducted according to these conventions will probably yield a better relationship between measured concentration and risk
15、of disease. NTE. For further information on the factors affecting inhalation and deposition, and their application in standards, see 181, 191, lo, ill, 1121 and 1131. 1 Scope This standard defines sampling conventions for particle size fractions which are to be used in assessing the possible health
16、effects resulting from inhalation of airborne particles in the workplace. They are derived from experimental data for healthy adults. Conventions are defined for the inhalable, thoracic and respirable fractions; extrathoracic and tracheobronchial conventions may be calculated from the defined conven
17、tions. (The inhalable fraction is sometimes called inspirable - the terms are equivalent. The nomenclature of the fractions is discussed in annex A.) Assumptions are given in clause 4. The convention chosen will depend on the region of effect of the component of interest in the airborne particles (s
18、ee clause 3). Conventions are stated in terms of mass fractions, but they may also be used when the intention is to evaluate the total surface area or the number of particles in the collected material. Page 3 EN 481 : 1993 In practice, the conventions will often be used to specify instruments to sam
19、ple airborne particles for the purpose of measuring concentrations corresponding to the defined fractions. It should be noted that experimental error in the testing of instruments, and possible dependence on factors other than aerodynamic diameter, mean that it is only possible to make a statement o
20、f probability that an instruments performance falls within a certain range, and that different instruments will fall within an acceptable range. NOTE. The problem of comparing instruments with the conventions is to be dealt with in another standard. One application is the comparison of mass concentr
21、ation of airborne size fractions with limit values. It should be noted with respect to relevant European Directives that the use of other methods is allowed provided that they yield the same or stricter conclusion. One important example is the respirable convention in relation to compliance with the
22、 limit value. Equipment matching the Johannesburg convention 21 will in practical circumstances give the same or a higher mass concentration (by up to about 20 %) than equipment matching the respirable convention given in 5.3, so the use of equipment matching the Johannesburg convention will be cons
23、istent with the European Directive. The conventions should not be used in association with limit values defined in completely different terms, for example for fibre limit values defined in terms of the length and diameter of fibres. 2 Definitions For the purposes of this standard, the following defi
24、nitions apply. 2.1 sampling convention A target specification for sampling instruments which approximates to, for each particle aerodynamic diameter: - in the case of inhalable convention, the ratio of the mass concentration of particles entering the respiratory tract to the corresponding mass conce
25、ntration in the air before the particles are affected by the presence of the exposed individual and inhalation; - in the case of the other conventions, the ratio of the mass concentration of particles entering the specified region of the respiratory tract to the mass concentration of particles enter
26、ing the respiratory tract. (These other conventions can also be expressed as ratios to the mass concentration of total airborne particles.) CEN EN*48L 93 3404589 0049059 64T Page 4 EN 481 : 1993 2.2 particle aerodynamic diameter The diameter of a sphere of density 1 g.cm-3 with the same terminal vel
27、ocity due to gravitational force in calm air, as the particle, under the prevailing conditions of temperature, pressure and relative humidity (see clause 4). NOTE. For particles of aerodynamic diameter less than 0,5 pm, the particle diffusion diameter should be used instead of the particle aerodynam
28、ic diameter. The particle diffusion diameter means the diameter of a sphere with the same diffusion coefficient as the particle under the prevailing conditions of temperature, pressure and relative humidity. 2.3 inhalable fraction The mass fraction of total airborne particles which is inhaled throug
29、h the nose and mouth. NCYE. The inhalable fraction depends on the speed and direction of the air movement, on breathing rate and other factors. 2.4 inhalable convention A target specification for sampling instruments when the inhalable fraction is the fraction of interest. 2.5 extrathoracic fraction
30、 The mass fraction of inhaled particles failing to penetrate beyond the larynx. 2.6 extrathoracic convention A target specification for sampling instruments when the extrathoracic fraction is of interest. 2.7 thoracic fraction The mass fraction of inhaled particles penetrating beyond the larynx. 2.8
31、 thoracic convention A target specification for sampling instruments when the thoracic fraction is of interest. 2.9 tracheobronchial fraction The mass fraction of inhaled particles penetrating beyond the larynx, but failing to penetrate to the unciliated airways. 2.10 tracheobronchial convention A t
32、arget specification for sampling instruments when the tracheobronchial fraction is of interest. 2.11 respirable fraction The mass fraction of inhaled particles penetrating to the unciliated airways. 2.12 respirable convention A target specification for sampling instruments when the respirable fracti
33、on is of interest. 2.13 total airborne particles All particles surrounded by air in a given volume of air. NOTE. Because ail measuring instruments are size-selective to some extent, it is often impossible to measure the total airborne particle concentration. 3 Principle of conventions The sampling c
34、onventions recognize that only a fraction of the airborne particles which are near to the nose and mouth is inhaled. This fraction is called the inhalable fraction (see 2.3). For some substances, the subfractions of this which penetrate beyond the larynx, or to the unciliated airways are of special
35、significance for health. This standard presents conventionalized curves approximating to the fraction inhaled and the subfractions reaching beyond the larynx or to the unciliated airways. These curves are called the inhalable convention (see 2.4), the thoracic convention (see 2.8) and the respirable
36、 convention (see 2.12). Extrathoracic (see 2.6) and tracheobronchial (see 2.10) conventions may be calculated from these. Instruments used for sampling need to conform with the sampling convention appropriate to the region of the respiratory tract where deposition of the substance being measured mig
37、ht lead to biological effect. For example, the inhalable convention would be chosen if the substance might lead to a biological effect wherever it deposited, the thoracic convention would be chosen if the region was the bronchi, and the respirable convention if the region was the alveoli. Instrument
38、s can be used to collect individual fractions according to the convent,ions, or to collect several fractions simultaneously. For example, an instrument could collect particles from the air according to the inhalable convention, and then separate this material into portions according to thoracic, tra
39、cheobronchial and respirable conventions. Alternatively, an instrument might just collect the respirable fraction from the air. In this case, the design would have to ensure that selection at the entry due to aerodynamic effects, and subsequently within the instrument, was such that the overall sele
40、ction was in accordance with the conventions. 4 Assumptions and approximations Approximations and assumptions are unavoidable in simulating by sampling conventions the very complex interaction of variables that governs respiratory tract entry and penetration. The conventions are necessarily only app
41、roximations to respiratory tract behaviour, and the foilowing assumptions are particularly important: - The inhalable fraction depends on air movement - speed and direction - on breathing rate, and on whether breathing is by nose or mouth. The values given in the inhalable convention are for represe
42、ntative values of breathing rate, and averaged for all wind CEN ENx48L 93 3404589 0049060 361 directions. This is appropriate for an individual uniformly exposed to all wind directions or predominantly to wind from the side or from behind. The convention usually underestimates the inhalable fraction
43、 of larger particles for an individual who usually faced the wind, particularly in windspeeds greater than 4 m.s-. - The respirable and thoracic fractions vary from individual to individual and with breathing pattern, and the conventions are necessarily approximatins to the average case. - Each conv
44、ention approximates to the fraction penetrating to a region, not to the fraction depositing there. In general, particles must deposit to have a biological effect. In this respect, the conventions will lead to an overestimate of the potential biological effect. The most important example is that the
45、respirable convention overestimates the fraction of very small particles which are deposited in the unciliated airways, because a fraction of these particles is exhaled without being deposited. In many workplaces, these very small particles do not contribute much to the sampled mass. - The thoracic
46、convention approximates to the thoracic fraction during mouth breathing, which is greater than the thoracic fraction during nose breathing. The extrathoracic convention can therefore underestimate the worst case extrathoracic fraction, which occurs during nose breathing. 5 Specifications for convent
47、ions 5.1 Inhalable convention Sampling of the inhalable fraction shall conform with the following convention: the percentage EI of airborne particles of aerodynamic diameter D in micrometres which are to be collected shall be given by: Some values given by this equation are given in table 1 and illu
48、strated in figure 1. NOTE. Experimental data on the inhalable fraction do not yet exist for D 100 pm, and the Convention should not be applied to larger particles. EI = 50(1 + exp-0,06D) (1) Page 5 EN 481 : 1993 5.2 Thoracic convention Sampling of the thoracic fraction shall conform with the followi
49、ng conventions: the percentage ET of the inhalable convention which is to be collected at an aerodynamic diameter D in micrometres shall be given by a cumulative log-normal distribution with a median of 11,64 pm and a geometric standard deviation of 1,5. A numerical approximation for ease of calculation is given in annex B. Note that ET is calculated from the inhalable convention. The fraction of the total airborne particles (see 2.13) at an aerodynamic diameter D is obtained by multiplying ET by 0,01E1 from equation (1). Some values obtained are given in table 1 a
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