EN ISO 7933:2004

Ergonomics of the thermal environment - Analytical determination and interpretation of heat stress using calculation of the predicted heat strain (ISO 7933:2004)

ISO 7933:2004 specifies a method for the analytical evaluation and interpretation of the thermal stress experienced by a subject in a hot environment. It describes a method for predicting the sweat rate and the internal core temperature that the human body will develop in response to the working conditions.
The various terms used in this prediction model, and in particular in the heat balance, show the influence of the different physical parameters of the environment on the thermal stress experienced by the subject. In this way, this International Standard makes it possible to determine which parameter or group of parameters should be modified, and to what extent, in order to reduce the risk of physiological strains.
The main objectives of ISO 7933:2004 are the following:
the evaluation of the thermal stress in conditions likely to lead to excessive core temperature increase or water loss for the standard subject;the determination of exposure times with which the physiological strain is acceptable (no physical damage is to be expected). In the context of this prediction mode, these exposure times are called "maximum allowable exposure times".
ISO 7933:2004 does not predict the physiological response of individual subjects, but only considers standard subjects in good health and fit for the work they perform. It is therefore intended to be used by ergonomists, industrial hygienists, etc., to evaluate working conditions.

Ergonomie der thermischen Umgebung - Analytische Bestimmung und Interpretation der Wärmebelastung durch Berechnung der vorhergesagten Wärmebeanspruchung (ISO 7933:2004)

Diese Internationale Norm legt ein Verfahren zur analytischen Bestimmung und Interpretation der Wärmebelastung fest, der eine Person in einer warmen Umgebung ausgesetzt ist. Beschrieben wird ein Verfahren zur Bestimmung der Schweißrate und der inneren Körperkerntemperatur, die der menschliche Körper als Reaktion auf die Arbeitsbedingungen entwickelt.
Die verschiedenen Bedingungen, die in diesem Vorhersagemodell und besonders bei der Wärmebilanz verwendet werden, zeigen den Einfluss der unterschiedlichen physikalischen Parameter der Umgebung auf die Wärme-belastung der Person. Auf diese Weise ermöglicht es diese Internationale Norm zu bestimmen, welche Parameter oder welche Gruppen von Parametern zu verändern sind und in welchem Ausmaß das erfolgen sollte, um das Risiko einer physiologischen Überbeanspruchung zu reduzieren.
Die Hauptziele dieser Internationalen Norm sind:
a)   die Bewertung der Wärmebelastung in Situationen, die zu einer übermäßigen Erhöhung der Körperkern-temperatur oder zu übermäßigem Wasserverlust einer "Normalperson" führen können;
b)   die Bestimmung der Expositionszeiten, bei denen die physiologische Beanspruchung annehmbar ist (d. h. keine körperlichen Schäden zu erwarten sind). Im Rahmen dieses Vorhersagemodells werden diese Expositionszeiten als "maximal zulässige Expositionszeiten" bezeichnet.
Diese Internationale Norm ist nicht in der Lage, die physiologische Reaktion einzelner Personen vorherzusagen, sondern berücksichtigt nur "Normalpersonen", die sich in einem guten gesundheitlichen Zustand befinden und in der Lage sind, ihre Arbeit durchzuführen. Diese Internationale Norm ist daher für die Anwendung durch Personen bestimmt, die im Bereich der Ergonomie, der Arbeitshygiene usw. ausgebildet sind, damit diese die Arbeitsbe-dingungen bewerten können

Ergonomie des ambiances thermiques - Détermination analytique et interprétation de la contrainte thermique fondées sur le calcul de l'astreinte thermique prévisible (ISO 7933:2004)

L'ISO 7933:2004 spécifie une méthode d'évaluation analytique et d'interprétation de la contrainte thermique subie par un sujet dans un environnement thermique chaud. Elle décrit une méthode permettant de prédire le débit sudoral et la température corporelle centrale que l'organisme humain met en oeuvre en réaction aux conditions de travail.
Les divers termes intervenant dans ce modèle prédictif, et notamment dans le bilan thermique, permettent de déterminer les parts respectives prises par les divers paramètres physiques de l'environnement dans la contrainte thermique subie par le sujet. L'ISO 7933:2004 permet ainsi de déterminer sur quel paramètre ou ensemble de paramètres il convient d'agir, et dans quelle mesure, afin de réduire le risque d'astreintes physiologiques.
Les principaux objectifs de l'ISO 7933:2004 sont les suivants:
l'évaluation de la contrainte thermique dans des environnements susceptibles d'entraîner une élévation de la température corporelle centrale ou des pertes hydriques importantes chez un sujet standard;
la détermination des durées d'exposition compatibles avec une astreinte physiologique tolérable (pas de dommage physique prévisible). Dans le cadre de ce modèle prédictif, ces durées sont dites «durées limites d'exposition admissibles».
L'ISO 7933:2004 ne vise pas à prédire la réponse physiologique d'un sujet donné, mais concerne uniquement un sujet standard en bonne santé et apte à faire son travail. Elle est par conséquent destinée à être utilisée par des ergonomes, des hygiénistes du travail, etc. pour évaluer les conditions de travail.

Ergonomija toplotnega okolja - Analitično ugotavljanje in razlaga toplotnega stresa z izračunom predvidene toplotne obremenitve (ISO 7933:2004)

General Information

• Status: Withdrawn
• Publication Date: 14-Aug-2004
• Withdrawal Date: 01-Aug-2023
• ICS: 13.180 - Ergonomics
• Technical Committee: CEN/TC 122 - Ergonomics
• Drafting Committee: CEN/TC 122/WG 11 - Ergonomics of the Physical Environment
• Ref Project: SIST EN ISO 7933:2004 - Ergonomics of the thermal environment - Analytical determination and interpretation of heat stress using calculation of the predicted heat strain (ISO 7933:2004)

Relations

• Replaces: EN 12515:1997 - Hot environments - Analytical determination and interpretation of thermal stress using calculation of required sweat rate (ISO 7933:1989 modified)
• Effective Date: 22-Dec-2008
• Replaced By: EN ISO 7933:2023 - Ergonomics of the thermal environment - Analytical determination and interpretation of heat stress using calculation of the predicted heat strain (ISO 7933:2023)
• Effective Date: 28-Jan-2023
• Revised: prEN ISO 7933 - Ergonomics of the thermal environment - Analytical determination and interpretation of heat stress using the predicted heat strain model (ISO/DIS 7933:2018)
• Effective Date: 18-Jan-2023

Standards Content (Sample)

SLOVENSKI STANDARD
01-november-2004
1DGRPHãþD
SIST EN 12515:2001
SIST ENV 26385:2001
(UJRQRPLMDWRSORWQHJDRNROMD$QDOLWLþQRXJRWDYOMDQMHLQUD]ODJDWRSORWQHJDVWUHVD
]L]UDþXQRPSUHGYLGHQHWRSORWQHREUHPHQLWYH,62
Ergonomics of the thermal environment - Analytical determination and interpretation of
heat stress using calculation of the predicted heat strain (ISO 7933:2004)
Ergonomie der thermischen Umgebung - Analytische Bestimmung und Interpretation der
Wärmebelastung durch Berechnung der vorhergesagten Wärmebeanspruchung (ISO
7933:2004)
Ergonomie des ambiances thermiques - Détermination analytique et interprétation de la
contrainte thermique fondées sur le calcul de l'astreinte thermique prévisible (ISO
7933:2004)
Ta slovenski standard je istoveten z: EN ISO 7933:2004
ICS:
13.180 Ergonomija Ergonomics
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 7933
NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2004
ICS 13.180 Supersedes EN 12515:1997
English version
Ergonomics of the thermal environment - Analytical
determination and interpretation of heat stress using calculation
of the predicted heat strain (ISO 7933:2004)
Ergonomie des ambiances thermiques - Détermination Ergonomie der thermischen Umgebung - Analytische
analytique et interprétation de la contrainte thermique Bestimmung und Interpretation der Wärmebelastung durch
fondées sur le calcul de l'astreinte thermique prévisible Berechnung der vorhergesagten Wärmebeanspruchung
(ISO 7933:2004) (ISO 7933:2004)
This European Standard was approved by CEN on 8 August 2004.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists 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 responsibility 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, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
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EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2004 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 7933:2004: E
worldwide for CEN national Members.

Foreword
This document (EN ISO 7933:2004) has been prepared by Technical Committee ISO/TC 159
"Ergonomics" in collaboration with Technical Committee CEN/TC 122 "Ergonomics", the
secretariat of which is held by DIN.

This European Standard shall be given the status of a national standard, either by publication of
an identical text or by endorsement, at the latest by February 2005, and conflicting national
standards shall be withdrawn at the latest by February 2005.

This document supersedes EN 12515:1997.

According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to implement this European Standard: Austria, Belgium,
Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary,
Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

Endorsement notice
The text of ISO 7933:2004 has been approved by CEN as EN ISO 7933:2004 without any
modifications.
INTERNATIONAL ISO
STANDARD 7933
Second edition
2004-08-15
Ergonomics of the thermal
environment — Analytical determination
and interpretation of heat stress using
calculation of the predicted heat strain
Ergonomie des ambiances thermiques — Détermination analytique et
interprétation de la contrainte thermique fondées sur le calcul de
l'astreinte thermique prévisible

Reference number
ISO 7933:2004(E)
©
ISO 2004
ISO 7933:2004(E)
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ii © ISO 2004 – All rights reserved

ISO 7933:2004(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope. 1
2 Normative references . 1
3 Symbols . 2
4 Principles of the method of evaluation. 5
5 Main steps of the calculation. 5
5.1 General heat balance equation. 5
5.2 Calculation of the required evaporative heat flow, the required skin wettedness and the
required sweat rate . 7
6 Interpretation of required sweat rate . 8
6.1 Basis of the method of interpretation . 8
6.2 Analysis of the work situation . 8
6.3 Determination of maximum allowable exposure time (D ) . 9
lim
6.4 Organization of work in the heat . 9
Annex A (normative) Data necessary for the computation of thermal balance. 10
Annex B (informative) Criteria for estimating acceptable exposure time in a hot work environment. 18
Annex C (informative) Metabolic rate . 20
Annex D (informative) Clothing thermal characteristics . 22
Annex E (informative) Computer programme for the computation of the Predicted Heat Strain
Model. 24
Annex F (normative) Examples of the Predicted Heat Strain Model computations . 33
Bibliography . 34

ISO 7933:2004(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member 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 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 Directives, 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 casting 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 7933 was prepared by Technical Committee ISO/TC 159, Ergonomics, Subcommittee SC 5, Ergonomics
of the physical environment.
This second edition cancels and replaces the first edition (ISO 7933:1989), which was based on the Required
Sweat Rate index. In order to avoid any confusion and, as extensive modifications are brought to the
prediction model, the name of the index has been changed to Predicted Heat Strain (PHS).
iv © ISO 2004 – All rights reserved

ISO 7933:2004(E)
Introduction
Other International Standards of this series describe how the parameters influencing the human
thermoregulation in a given environment must be estimated or quantified. Others specify how these
parameters must be integrated in order to predict the degree of discomfort or the health risk in these
environments. The present document was prepared to standardize the methods that occupational health
specialists should use to approach a given problem and progressively collect the information needed to
control or prevent the problem.
The method of computation and interpretation of thermal balance is based on the latest scientific information.
Future improvements concerning the calculation of the different terms of the heat balance equation, or its
interpretation, will be taken into account when they become available. In its present form, this method of
assessment is not applicable to cases where special protective clothing (reflective clothing, active cooling and
ventilation, impermeable, with personal protective equipment) is worn.
In addition, occupational health specialists are responsible for evaluating the risk encountered by a given
individual, taking into consideration his specific characteristics that might differ from those of a standard
subject. ISO 9886 describes how physiological parameters must be used to monitor the physiological
behaviour of a particular subject and ISO 12894 describes how medical supervision must be organized.

INTERNATIONAL STANDARD ISO 7933:2004(E)

Ergonomics of the thermal environment — Analytical
determination and interpretation of heat stress using
calculation of the predicted heat strain
1 Scope
This International Standard specifies a method for the analytical evaluation and interpretation of the thermal
stress experienced by a subject in a hot environment. It describes a method for predicting the sweat rate and
the internal core temperature that the human body will develop in response to the working conditions.
The various terms used in this prediction model, and in particular in the heat balance, show the influence of
the different physical parameters of the environment on the thermal stress experienced by the subject. In this
way, this International Standard makes it possible to determine which parameter or group of parameters
should be modified, and to what extent, in order to reduce the risk of physiological strains.
The main objectives of this International Standard are the following:
a) the evaluation of the thermal stress in conditions likely to lead to excessive core temperature increase or
water loss for the standard subject;
b) the determination of exposure times with which the physiological strain is acceptable (no physical
damage is to be expected). In the context of this prediction mode, these exposure times are called
“maximum allowable exposure times”.
This International Standard does not predict the physiological response of individual subjects, but only
considers standard subjects in good health and fit
...