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1、 Reference number ISO 8996:2004(E) ISO 2004 INTERNATIONAL STANDARD ISO 8996 Second edition 2004-10-01 Ergonomics of the thermal environment Determination of metabolic rate Ergonomie de lenvironnement thermique Dtermination du mtabolisme nergtique Copyright International Organization for Standardizat
2、ion Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/16/2007 10:04:39 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 8996:2004(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing pol
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7、 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2004 All rights reserved Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/16/2007 10:04:39 MDTNo reproduction
8、 or networking permitted without license from IHS -,-,- ISO 8996:2004(E) ISO 2004 All rights reserved iii Contents Page Forewordiv 1 Scope1 2 Normative references .1 3 Principle and accuracy.1 4 Level 1, screening.3 4.1 Table for the estimation of metabolic rate by occupation3 4.2 Classification of
9、metabolic rate by categories 3 5 Level 2, observation3 5.1 Estimation of metabolic rate by task requirements 3 5.2 Metabolic rate for typical activities .4 5.3 Metabolic rate for a work cycle4 5.4 Influence of the length of rest periods and work periods.5 5.5 Obtaining values by interpolation.6 5.6
10、Requirements for the application of metabolic-rate tables6 6 Level 3, analysis6 6.1 Estimation of metabolic rate using heart rate6 6.2 Relationship between heart rate and metabolic rate.7 7 Level 4, expertise 8 7.1 Determination of metabolic rate by measurement of oxygen consumption rate.8 7.2 The d
11、oubly labelled water method for long-term measurements14 7.3 Direct calorimetry Principle.14 Annex A (informative) Evaluation of the metabolic rate at level 1, screening .15 Annex B (informative) Evaluation of the metabolic rate at level 2, observation17 Annex C (informative) Evaluation of the metab
12、olic rate at level 3, analysis 20 Annex D (informative) Evaluation of the metabolic rate at level 4, expertise Examples of the calculation of metabolic rate based on measured data21 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/998
13、0755100 Not for Resale, 04/16/2007 10:04:39 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 8996:2004(E) iv ISO 2004 All rights reserved Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member
14、bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental
15、and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directive
16、s, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies c
17、asting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 8996 was prepared by Technical Committee ISO/TC 159, Ergonomics, Subcommittee SC 5
18、, Ergonomics of the physical environment. This second edition cancels and replaces the first edition (ISO 8996:1990), which has been technically revised. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/1
19、6/2007 10:04:39 MDTNo reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARD ISO 8996:2004(E) ISO 2004 All rights reserved 1 Ergonomics of the thermal environment Determination of metabolic rate 1 Scope The metabolic rate, as a conversion of chemical into mechanic
20、al and thermal energy, measures the energetic cost of muscular load and gives a numerical index of activity. Metabolic rate is an important determinant of the comfort or the strain resulting from exposure to a thermal environment. In particular, in hot climates, the high levels of metabolic heat pro
21、duction associated with muscular work aggravate heat stress, as large amounts of heat need to be dissipated, mostly by sweat evaporation. This International Standard specifies different methods for the determination of metabolic rate in the context of ergonomics of the climatic working environment.
22、It can also be used for other applications for example, the assessment of working practices, the energetic cost of specific jobs or sport activities, the total cost of an activity, etc. The estimations, tables and other data included in this International Standard concern an “average” individual: a
23、man 30 years old weighing 70 kg and 1,75 m tall (body surface area 1,8 m2); a woman 30 years old weighing 60 kg and 1,70 m tall (body surface area 1,6 m2). Users should make appropriate corrections when they are dealing with special populations including children, aged persons, people with physical
24、disabilities, etc. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 988
25、6, Ergonomics Evaluation of thermal strain by physiological measurements ISO 15265, Ergonomics of the thermal environment Risk assessment strategy for the prevention of stress or discomfort in thermal working conditions 3 Principle and accuracy The mechanical efficiency of muscular work called the “
26、useful work”, W is low. In most types of industrial work, it is so small (a few percent) that it is assumed to be nil. This means that the total energy consumption while working is assumed equal to the heat production. For the purposes of this International Standard, the metabolic rate is assumed to
27、 be equal to the rate of heat production. Table 1 lists the different approaches presented in this International Standard for determining the metabolic rate. These approaches are structured following the philosophy exposed in ISO 15265 regarding the assessment of exposure. Four levels are considered
28、 here: Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/16/2007 10:04:39 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 8996:2004(E) 2 ISO 2004 All rights reserved Level 1,
29、screening: Two methods simple and easy to use are presented to quickly characterize the mean workload for a given occupation or for a given activity: method 1A is a classification according to occupation; method 1B is a classification according to the kind of activity. Both methods provide only a ro
30、ugh estimate and there is considerable scope for error. This limits their accuracy considerably. At this level, an inspection of the work place is not necessary. Level 2, observation: Two methods are presented for people with full knowledge of the working conditions but without necessarily a trainin
31、g in ergonomics, to characterize, on average, a working situation at a specific time: in method 2A, the metabolic rate is determined by adding to the baseline metabolic rate the metabolic rate for body posture, the metabolic rate for the type of work and the metabolic rate for body motion related to
32、 work speed (using group assessment tables); in method 2B, the metabolic rate is determined by means of the tabulated values for various activities. A procedure is described to record the activities with time and compute the time-weighted average metabolic rate, using the data from the two methods a
33、bove. The possibility for errors is high. A time and motion study is necessary to determine the metabolic rate in work situations that involve a cycle of different activities. Level 3, analysis: One method is addressed to people trained in occupational health and ergonomics of the thermal environmen
34、t. The metabolic rate is determined from heart rate recordings over a representative period. This method for the indirect determination of metabolic rate is based on the relationship between oxygen uptake and heart rate under defined conditions. Level 4, expertise: Three methods are presented. They
35、require very specific measurements made by experts: in Method 4A, the oxygen consumption is measured over short periods (10 min to 20 min) (a detailed time and motion study is necessary to show the representativity of the measurement period); method 4B is the so-called doubly labelled water method a
36、iming at characterizing the average metabolic rate over much longer periods (1 to 2 weeks); method 4C is a direct calorimetry method. The main factors affecting the accuracy of the estimations are the following: individual variability; differences in the work equipment; differences in work speed; di
37、fferences in work technique and skill; gender differences and anthropometric characteristics; cultural differences; when using the tables, differences between observers and their level of training; Copyright International Organization for Standardization Provided by IHS under license with ISO Licens
38、ee=Aramco HQ/9980755100 Not for Resale, 04/16/2007 10:04:39 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 8996:2004(E) ISO 2004 All rights reserved 3 when using level 3, the accuracy of the relationship between heart rate and oxygen uptake, as other stress factors als
39、o influence the heart rate; at level 4, the measurement accuracy (determination of gas volume and oxygen fraction). The accuracy of the results, but also the costs of the study, increase from level 1 to level 4. Measurement at level 4 gives the most accurate values. As far as possible, the most accu
40、rate method should be used. Table 1 Levels for the determination of the metabolic rate Level Method Accuracy Inspection of the work place 1A: Classification according to occupation Not necessary, but information needed on technical equipment, work organization 1 Screening 1B: Classification accordin
41、g to activity Rough information Very great risk of error 2A: Group assessment tables Time and motion study necessary 2 Observation 2B: Tables for specific activities High error risk Accuracy: 20 % 3 Analysis Heart rate measurement under defined conditions Medium error risk Accuracy: 10 % Study requi
42、red to determine a representative period 4A: Measurement of oxygen consumption Time and motion study necessary 4B: Doubly labelled water method Inspection of work place not necessary, but leisure activities must be evaluated. 4 Expertise 4C: Direct calorimetry Errors within the limits of the accurac
43、y of the measurement or of the time and motion study Accuracy: 5 % Inspection of work place not necessary 4 Level 1, screening 4.1 Table for the estimation of metabolic rate by occupation Table A.1 in Annex A shows the metabolic rate for different occupations. The values are mean values for the whol
44、e working time, but without considering longer rest pauses, for example lunchtime. Significant variation may arise due to differences in technology, work elements, work organization, etc. 4.2 Classification of metabolic rate by categories The metabolic rate can be estimated approximately using the c
45、lassification given in Annex A. Table A.2 defines five classes of metabolic rate: resting, low, moderate, high, very high. For each class, an average and a range of metabolic rate values are given as well as a number of examples. These activities are supposed to include short rest pauses. The exampl
46、es given in Table A.2 illustrate the classification. 5 Level 2, observation 5.1 Estimation of metabolic rate by task requirements Here, the metabolic rate is estimated from the following observations: the body segment involved in the work: both hands, one arm, two arms, the entire body; Copyright In
47、ternational Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/16/2007 10:04:39 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 8996:2004(E) 4 ISO 2004 All rights reserved the workload for that body s
48、egment: light, medium, heavy, as judged subjectively by the observer; the body posture: sitting, kneeling, crouching, standing, standing stooped; the work speed. Table B.1 in Annex B gives the mean value and the range of metabolic rates for a standard person, seated, as a function of the body segment involved and the workload. Table B.2 gives the corrections to be added when the posture is different from seated. 5.2 Metabolic rate for typical activities Table B.3