ISO/TR 22100-3:2016
(Main)Safety of machinery — Relationship with ISO 12100 — Part 3: Implementation of ergonomic principles in safety standards
Safety of machinery — Relationship with ISO 12100 — Part 3: Implementation of ergonomic principles in safety standards
ISO/TR 22100-3:2016 describes the main ergonomic risk factors influencing the safety of machinery and gives a framework for incorporating them into the design of machines by the integration of important ergonomic principles relating to: - avoiding stressful postures and movements during use of the machine; - designing machines, and more especially hand-held and mobile machines, which can be operated easily; - avoiding as far as possible noise, vibration, thermal effects; NOTE 1: The health effects of noise, vibration and adverse thermal conditions are well-known and are not addressed here. However environmental factors can interact with machine design and risks arising from such influences are addressed in this document. ? avoiding linking the operator's working rhythm to an automatic succession of cycles; ? providing local lighting on or in the machine; NOTE 2: Lighting of the machine or of the surrounding workplace by the machine can have a significant impact on the safety of machine operation and this risk is addressed by this document. - selecting, locating and identifying manual controls (actuators) so that they are clearly visible and identifiable and appropriately marked where necessary; - selecting, designing and locating indicators, dials and visual display units. The approach is based on ISO 12100 with its iterative process to identify significant hazards and reduce risks. Relevant steps of this iterative process have been adapted to include ergonomic principles, and practical guidance is given to apply standards dealing with ergonomics which are relevant for machinery design. ISO/TR 22100-3:2016 is intended for use by standards writers and designers of machinery. It can be used when no relevant C-type standards are available.
Sécurité des machines — Relation avec l'ISO 12100 — Partie 3: Mise en oeuvre des principes ergonomiques dans les normes de sécurité
General Information
Standards Content (Sample)
TECHNICAL ISO/TR
REPORT 22100-3
First edition
Safety of machinery — Relationship
with ISO 12100 —
Part 3:
Implementation of ergonomic
principles in safety standards
Sécurité des machines — Relation avec l’ISO 12100 —
Partie 3: Mise en oeuvre des principes ergonomiques dans les normes
de sécurité
PROOF/ÉPREUVE
Reference number
©
ISO 2016
© ISO 2016, Published in Switzerland
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ii © ISO 2016 – All rights reserved
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Strategy for risk assessment and risk reduction in relation to ergonomics hazards .2
4.1 General . 2
4.2 Significant ergonomic hazards in relation to ISO 12100 . 4
4.3 Potential consequences . 4
4.3.1 General. 4
4.3.2 Discomfort . 4
4.3.3 Fatigue . 5
4.3.4 Musculoskeletal disorders . 5
4.3.5 Stress . 6
4.3.6 Human error . 7
5 Incorporating ergonomics into the risk assessment process . 8
5.1 Information for risk assessment . 8
5.1.1 General. 8
5.1.2 Information for establishing assessment criteria . 8
5.2 Determination of limits of machinery (user aspects) . 9
5.3 Hazard identification . 9
5.3.1 General concept for identifying ergonomic hazards . 9
5.3.2 Determination of hazards based on essential characteristics and
capabilities of intended operator population . 9
5.4 Risk estimation .13
5.4.1 General.13
5.4.2 Risk estimation tools .13
5.5 Risk evaluation .13
5.5.1 General.13
5.5.2 Evaluating the risk reduction achieved by the application of
ergonomics principles .13
5.5.3 Comparison of ergonomics risks .14
6 Risk reduction — Design guidance .14
6.1 General .14
6.2 Risk reduction — Human variability .14
6.3 Risk reduction — Posture and movement space .15
6.4 Risk reduction — Work rate and pattern .16
6.5 Risk reduction - Human error .16
6.6 Risk reduction — Operator/machine interface .17
6.7 Risk reduction — Workplace environment .18
6.7.1 General.18
6.7.2 Visual factors .18
6.7.3 Auditory factors .19
6.7.4 Vibration factors.19
6.7.5 Thermal factors .19
7 Verification of safety requirements .19
Annex A (informative) Standards dealing with ergonomics relevant to machinery design .20
Annex B (informative) Work system and machinery design .24
Annex C (informative) Ergonomics standards for specific applications .29
Annex D (informative) Example of part of the implementation of the ergonomics factors .30
Bibliography .34
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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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment,
as well as information about ISO’s adherence to the World Trade Organization (WTO) principles in the
Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html
The committee responsible for this document is ISO/TC 199, Safety of machinery.
ISO/TR 22100 consists of the following parts, under the general title Safety of machinery — Relationship
with ISO 12100:
— Part 1: How ISO 12100 relates to type-B and type-C standards
— Part 2: How ISO 12100 relates to ISO 13849-1
— Part 3: Implementation of ergonomic principles in safety standards
Introduction
The primary purpose of this document is to provide designers with an overall framework and guidance
for decisions about ergonomic aspects during the development of machinery, to help them design
machines that are safe for their intended use. As mentioned in ISO 12100:2010, 6.2.8, failure to follow
ergonomic principles in design can result in the inadequate adaptation of machines to the capacities
and skills of the intended user population and hence place their health or safety at risk.
ISO 12100 describes an iterative process to reduce risks. This document describes the main ergonomic
factors influencing the safety of machinery and gives a framework for incorporating them into this
design process.
Mental (cognitive) aspects are also to be considered. For example, machines which are operated in an
inappropriate manner or whose control devices are not clearly identifiable can lead to human error.
This document is intended to guide users to make effective use of ergonomics standards within the
context of machinery design.
This document will help both ergonomics and machinery standards writers to incorporate the structure
specified in ISO Guide 78.
vi PROOF/ÉPREUVE © ISO 2016 – All rights reserved
TECHNICAL REPORT ISO/TR 22100-3:2016(E)
Safety of machinery — Relationship with ISO 12100 —
Part 3:
Implementation of ergonomic principles in safety
standards
1 Scope
This document describes the main ergonomic risk factors influencing the safety of machinery and
gives a framework for incorporating them into the design of machines by the integration of important
ergonomic principles relating to:
— avoiding stressful postures and movements during use of the machine;
— designing machines, and more especially hand-held and mobile machines, which can be operated
easily;
— avoiding as far as possible noise, vibration, thermal effects;
NOTE 1 The health effects of noise, vibration and adverse thermal conditions are well-known and are not
addressed here. However environmental factors can interact with machine design and risks arising from such
influences are addressed in this document.
— avoiding linking the operator’s working rhythm to an automatic succession of cycles;
— providing local lighting on or in the machine;
NOTE 2 Lighting of the machine or of the surrounding workplace by the machine can have a significant impact
on the safety of machine operation and this risk is addressed by this document.
— selecting, locating and identifying manual controls (actuators) so that they are clearly visible and
identifiable and appropriately marked where necessary;
— selecting, designing and locating indicators, dials and visual display units.
The approach is based on ISO 12100 with its iterative process to identify significant hazards and
reduce risks.
Relevant steps of this iterative process have been adapted to include ergonomics principles, and practical
guidance is given to apply standards dealing with ergonomics which are relevant for machinery design.
This document is intended for use by standards writers and designers of machinery. It can be used
when no relevant C-type standards are available.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 12100:2010, Safety of machinery — General principles for design — Risk assessment and risk reduction
3 Terms and definitions
For the purposes of this document, the the terms and definitions given in ISO 12100 and the following.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at http://www.iso.org/obp
3.1
ergonomics
study of human factors
scientific discipline concerned with the understanding of interactions among human and other elements
of a system, and the profession that applies theory, principles, data and methods to design in order to
optimize human well-being and overall system performance
[SOURCE: ISO 6385:2004, 2.3]
3.2
ergonomic hazard
hazard arising from the failure to adequately consider ergonomics principles in machine design
Note 1 to entry: For ergonomic hazards see also ISO 12100:2010, Table B.1, No. 8.
4 Strategy for risk assessment and risk reduction in relation to ergonomics
hazards
4.1 General
The risk assessment process carried out by designers in accordance with ISO 12100:2010, Clause 5,
provides information that is required for the risk evaluation through which decisions can be taken
whether risk reduction is necessary. These decisions have to be supported by a qualitative or, where
appropriate, a quantitative estimation of the risk identified. This is to be met by taking into account
both the risks normally considered in machine design, and those arising from failing to consider the
principles of ergonomics.
Figure 1 shows a schematic representation of the risk reduction process, derived from ISO 12100:2010,
which illustrates how ergonomics can be integrated into the iterative three-step risk reduction process
(including references to the relevant clauses in this document).
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Figure 1 — Illustration of the integration of ergonomics into the iterative three-step design
process for risk reduction (based on ISO 12100:2010, Figure 1)
4.2 Significant ergonomic hazards in relation to ISO 12100
Designs which do not take ergonomics into account can have potential consequences such as discomfort,
fatigue, musculoskeletal disorders, stress and human error (see 4.3). When these are identified as being
associated with the machine, they are relevant ergonomics hazards. Consequences such as discomfort
and fatigue can also lead indirectly to human error. If the potential consequences require specific action,
then these are significant hazards and are as important as those arising from mechanical, electrical
and other hazards (see ISO 12100:2010, Table B.1).
NOTE 1 Discomfort and fatigue are relevant warning signals, as they may lead to occupational disease or to
accidents and can influence performance and quality.
NOTE 2 The term ergonomic hazard is used in ISO 12100 to describe hazards resulting from the failure to
adequately consider ergonomics during the design process. For consistency this term is therefore retained in this
document.
Table 1 shows an example comparing mechanical hazards with ergonomics hazards.
Table 1 — Comparison of mechanical and ergonomics aspects of hazards
Work task: load/unload a machine
Location of hazard: machine loading area
Hazards arising from the failure
Mechanical aspects Ergonomics aspects
to adequately consider
Origin of hazard Sharp edge Sustained awkward posture
Factors influencing the risk Surface characteristics Space for movement restricted
Potential consequences Cutting Discomfort/Fatigue
Harm Injury, pain, bleeding Back pain, musculoskeletal disorders
Severity of harm Light to serious damage to health Light to serious damage to health
(reversible or chronic)
4.3 Potential consequences
4.3.1 General
Taking ergonomics principles into account in designing machinery helps to reduce the mental or
physical load on the operator. In turn this reduces strain and improves efficiency. It is important to
consider these principles when allocating functions to operator and machine in the basic design.
As outlined in ISO 12100, failure to consider these principles can have potential consequences for
the health, safety and performance of the operator. Table B.1 of ISO 12100:2010 lists some of these
consequences which are described below.
4.3.2 Discomfort
Discomfort refers to a lack of comfort, to a mental or physical uneasiness that is less intense and less
localized than pain. On the contrary, comfort gives or brings aid, support, satisfaction. Comfort refers
to a condition furnishing mental and/or physical ease. Sustained discomfort can lead to
— lack of attention or concentration (distraction),
— ill-health,
— absenteeism,
— decreased productivity — both qualitatively (with more discarded items) and quantitatively, and
— accidents.
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Important aspects contributing to discomfort are
— awkward postures or sustained (static) postures,
— heavy physical work,
— repetitive movements,
— accessibility e.g. reaching distances,
— visual comfort, e.g. lines of sight, colour, visibility, light intensity and direction, viewing distances,
— surface contact e.g. shape, temperature, ease of contact,
— vibration (whole body and hand-arm),;
— noise e.g. intensity, frequency, duration, pattern,
— climate/environment e.g. air temperature, wind speed (draught), relative humidity, clothing,
— odours e.g. fumes,
— inadequate cooperation or communication between operators during machine operation,
— balance between activity and inactivity; between vigilance and inattentiveness.
4.3.3 Fatigue
Fatigue is a state of impaired performance capability which can result from current or preceding
physical and/or mental activities. Fatigue can be physical or mental, general or local. The extent of
any fatigue depends on the intensity, duration and temporal pattern of these activities. Recovery from
fatigue requires rest periods with sufficient time for recuperation.
Important aspects contributing to fatigue are:
— type of workload, e.g. mental or physical;
— intensity of the workload, e.g. weight to be moved, complexity of information to be processed;
— repetitiveness of task components (highly repetitive tasks can be more fatiguing);
— time for recovery e.g. rest breaks.
NOTE As well as variation in mental and physical capabilities between different operators, the capabilities
of an individual operator and therefore their susceptibility to fatigue and other effects will vary over time.
4.3.4 Musculoskeletal disorders
Musculoskeletal disorders can be either acute or chronic. Acute disorders usually arise from some
form of muscle overload, with work which is either too demanding, or with other characteristics such
as sudden onset, which can tear or strain muscles or other soft tissue structures.
Chronic disorders usually arise from sustained or repeated demands which exceed the body’s
recovery and repair mechanisms. In some instances, unaccustomed activities create a hazard and an
introductory or learning period can be beneficial.
Some disorders can be either acute or chronic in origin. For example, some tendon problems can arise
from a short-term overload (acute) or a more sustained period of repeated activity.
Static loading (force application without movement) can also be problematic as muscle movement is an
essential part of the recovery and repair process.
Important aspects contributing to musculoskeletal disorders:
— force requirements (are related to the size of the body part involved, with larger muscles being
generally capable of higher forces);
— frequency of movements (smaller body parts such as fingers are naturally better suited to rapid
movements than larger joints such as the shoulder);
— duration of force application (the greater the force, the less time it can be sustained for, especially
without movement);
— position of body parts – posture - (body parts are more resilient when working close to their
anatomical neutral position, such as with the arms by the side rather than raised above the
shoulders);
— range of joint movement (as a rough guide, remaining within the middle 50 % of the range of
movement is preferable and the more extreme a movement or posture the more strain will be
experienced).
NOTE External environmental loads, such as vibration (hand-arm or whole-body) or extremes of
temperature may need to be taken into account. This document does not cover noise and vibration requirements.
4.3.5 Stress
4.3.5.1 General
The terminology relating to “stress” is often both confused and confusing. In some instances, the term
is used in the equivalent manner to the engineering use of the term, to reflect the loads placed on a
person (with the outcome regarded as ‘strain’). In others, these are referred to as stressors, with the
impact regarded as stress. Still others term the loads as pressure – again with stress as the potential
outcome.
When used in the engineering sense, the term is essentially neutral and stress can be beneficial or
harmful depending upon its characteristics. In other instances however, stress as an outcome is, by
definition an adverse consequence.
Both fatigue and discomfort, addressed above, can be caused by physical and psychological stressors.
However, although the volume of work can be a contributor to psychological stress it is more usually
psychological factors which combine to give rise to the negative outcome. For this reason in some
countries, to avoid any confusion, the term “psychological stress” is used instead.
NOTE 1 Psychological stressors can also aggravate existing fatigue and discomfort.
NOTE 2 Psychological stress is sometimes referred to as mental stress.
4.3.5.2 Psychological stress
In a safety of machinery context, it is likely to be issues such as the complexity and variability of the
tasks required of operators and others, together with cognitive factors such as requirements for
sustained attention and the probability and consequences of errors which contribute to any risk.
Important aspects contributing to psychological stress, which may be influenced by the design of the
machine, include
— complexity of task,
— variability of task,
— time constraints on performance,
— cognitive resources required,
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— multitasking vs. serial task performance,
— probability of errors,
— consequences of errors,;
— design of interfaces (e.g. displays, signals and controls),
— requirements for sustained attention,
— repetitiveness of task performance,
— intensity of workload, and
— temporal pattern of workload.
The general factors which contribute to the overall burden of psychological stress can be grouped into
six broad categories:
1) demands (not being able to cope with the demands of the job);
2) control (not having sufficient influence over how work is done);
3) support (not having sufficient support from colleagues and superiors);
4) relationships (being subjected to unacceptable behaviours);
5) role (not understanding roles and responsibilities);
6) change (not being involved and informed in organisational changes).
However, central to the concept of psychological stress, and a major mediating influence over whether
the demands placed on an individual become excessive, is the idea of the individual ‘coping’ with
the demands placed upon them. Thus, psychological stress develops when work demands of various
types and combinations exceed the person’s capacity and capability to cope. The consequences can be
considerable including poor mental wellbeing, anxiety or depression as well as contributing to physical
ill-health.
4.3.6 Human error
Human error, which can be expressed as a discrepancy between the human action taken or omitted,
and that intended or required is a very complex field, with many different approaches to defining
and classifying errors. In a safety of machine design context, the focus turns to the potential for
human error by the designer, in failing to adequately ensure that controls or displays can be clearly
and unambiguously identified and operated correctly in accordance with operator expectations
(stereotypes).
In essence, errors can occur when a person does something they shouldn’t (e.g. operating the wrong
control device) or doesn’t do something they should (e.g. spotted a warning signal). However, the
complexities increase when the possibilities are explored further. Thus, was the wrong control device
activated, the right one operated wrongly, the right one operated at the wrong time, and so on. Do the
consequences arise from the failure to operate the right control device – or the operation of the wrong
one? The likelihood of error is also influenced by additional factors such as work demands or pressures,
sustained vigilance, monotony, etc.
Some important machine design aspects contributing to human error are
— selection of inappropriate display designs (e.g. digital or analogue displays),
— inappropriate control design (e.g. small devices to be operated by gloved hands),
— inappropriate control-response relationships (e.g. direction of control movement in relation to the
movement of the machine),
— poorly identified control devices or displays (e.g. inadequate labelling, wrong colour coding);
— poor layout of control devices (e.g. insufficient space between devices), and
— poor layout of displays (e.g. viewing angle from operating position).
This list presents aspects through which poorly considered design can increase the risk of human error
and avoiding these through good design will improve machine safety.
5 Incorporating ergonomics into the risk assessment process
5.1 Information for risk assessment
5.1.1 General
5.2 to 5.5 describe the steps for incorporating ergonomics into the risk assessment process in
accordance with ISO 12100:2010, Clause 5.
Because ergonomics deals with interactions between people and other elements of a system, special
attention should be drawn to the overall work system (see ISO 6385), which is the basis for the
determination of the limits of the machinery [see ISO 12100:2010, 5.2 d) and 5.3].
5.1.2 Information for establishing assessment criteria
Establishing assessment criteria requires knowledge of the technical design of the machine and the
characteristics and capabilities of the intended operator population including their experience and
training with similar machines.
In order to perform an adequate risk assessment, the following basic parameters of the machine should
be defined:
a) functions and their limits;
b) human interfaces with different parts of the machine.
The determination of the characteristics of the operator population is based on
— physical limitations (stature, reach, strength, vision, etc.), and
— mental ability (education, training, experience, etc.).
Essential information for risk assessment is required relating to
— the functionality of the machine,
— the allocation of function between manual and automated processes,
— the job (task elements),
— the human/machine interface characteristics,
— where the machine will be installed,
— how the machine will be used (including maintenance) and removed,
— information for training of personnel, and
— production and maintenance procedures.
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5.2 Determination of limits of machinery (user aspects)
Risk assessment starts with the determination of the limits of the machinery, which includes taking
into account the characteristics and capabilities of the intended operator population.
NOTE The limits of machinery can be part of the contract between the supplier and user of a machine.
5.3 Hazard identification
5.3.1 General concept for identifying ergonomic hazards
Human error, musculoskeletal disorders, stress, discomfort and fatigue are potential consequences
arising from ergonomic hazards which result from the failure to adequately consider ergonomics
during the design process (see ISO 12100:2010, 5.4 a) and 5.4 c)).
Important ergonomic risk factors to be taken into account include
— human variability,
— posture and movement space,
— work rate and pattern,
— human error,
— operator/machine interface, and
— workplace environment.
Detailed information relating to the determination of hazards based on the essential characteristics
and capabilities of the intended operator population is given in 5.3.2.1 to 5.3.2.7.
5.3.2 Determination of hazards based on essential characteristics and capabilities of intended
operator population
5.3.2.1 General
Particular attention is drawn to the following seven ergonomic aspects of machinery design (see
ISO 12100:2010, 6.2.8) that should be considered when identifying hazards:
a) forces, postures and movements during use of the machine;
b) operability or controllability of the machine, especially hand-held and mobile machines;
c) environmental effects of the machine and its surroundings (e.g. noise, vibration, thermal);
d) operator’s working rhythm linked to an automatic succession of cycles;
e) integral task lighting (on or in the machine);
f) selection, design and location of control devices;
g) selection, design and location of indicators, dials and visual display units.
In order to help address these aspects, this document describes six important ergonomics risk factors
that need to be considered. Each factor is relevant to one or more of the above ergonomic aspects. The
main links between these factors (1 through 6) and the aspects a, b, c, d, e, f and g relating to them are
described in the text below and summarized in Table 2.
Table 2 — Link between ergonomics risk factors and ergonomics aspects
Ergonomics risk factor Ergonomics aspects of machinery design
1) Human variability a) forces, postures and movements during use of the machine
b) operability or controllability of the machine, especially hand-held and mo-
bile machines
2) Posture and move- a) forces, postures and movements during use of the machine
ment space
b) operability or controllability of the machine, especially hand-held and mo-
bile machines
d) operator’s working rhythm linked to an automatic succession of cycles
3) Work rate and pattern d) operator’s working rhythm linked to an automatic succession of cycles
4) Human error c) environmental effects of the machine and its surroundings (e.g. noise,
vibration, thermal)
e) integral task lighting (on or in the machine)
f) selection, design and location of control devices
g) selection, design and location of indicators, dials and visual display units
5) Operator/machine f) selection, design and location of control devices
interface
g) selection, design and location of indicators, dials and visual display units
6) Workplace environment c) environmental effects of the machine and its surroundings (e.g. noise,
vibration, thermal)
e) integral task lighting (on or in the machine)
NOTE General ergonomic design standards are listed in Annex A, see Table A.1.
5.3.2.2 Human variability
Human beings differ widely in their attributes. When addressing this variability in the design process,
the main factors to be taken into account are physical dimensions, strength (and stamina). These should
be considered by taking into account gender, body dimensions and build, age, body weight and physical
strength and disabilities. Psychological or cognitive factors may also need to be considered depending
on the nature and function of the machine being designed (e.g. skills and experience).
Body dimensions can vary between different populations, more usually between countries from different
parts of the world but, particularly in some larger or more diverse countries, from region to region.
Age-related adverse effects can be partly compensated by training and/or assistive technology. Other
adverse effects of age can be compensated by operators adopting different strategies. Older people
generally have more experience and higher decision-making capabilities than their younger peers.
Individual performance (e.g. vigilance) and capacity will vary not only with age, but also throughout a
working day with generally poorer cognitive performance as fatigue develops.
NOTE 1 In particular instances it may be appropriate to consider health-related impairments, e.g. reduction in
grip strength due to osteoarthritis, operators with pacemakers etc.
NOTE 2 The impact of some aspects of human variability can be modified or offset. For example: strength can
be increased (by physical training); additional skills can be gained.
NOTE 3 Standards dealing with significant hazards associated with human variability are listed in Annex A,
see Tables A.2 and Table A.3
5.3.2.3 Posture and movement space
The space necessary for the operator(s) postures and movements needed for machine operation should
be taken into account in any design process.
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Sustained working postures, such as sitting, standing, trunk bending, kneeling; together with tasks
requiring the arms to be used above shoulder height can be critical if the posture is sustained or
repeated for long periods. Twisting movements or extreme positions of the hand or arm, as well as
repetitive body movements, especially where they involve the application of forces, should be avoided.
Sufficient space for movement is one of the basic principles in machinery design to prevent accidents
and occupational diseases e.g. musculoskeletal disorders. Restricting movement can potentially be as
harmful as requiring too great a range of movement. Appropriate body movements are indispensable to
avoid physical stress and strain.
Anthropometric data for the intended operating population and knowledge of their work tasks are
therefore important factors in identifying potential hazards arising from any mismatch between the
dimensions of the human body and the size and dimensions allowed for in any machine design.
It should be remembered that worker’s tasks are not limited to regular machine operating functions.
Maintenance, troubleshooting, repairing and installing machinery are important tasks to consider and
can give rise to risks. The need for access to danger zones for maintenance, lubrication and setting
should be minimized. However, if needed, factors such as the access space and postures required to
reach machine parts for these tasks should be taken into account during the design process.
NOTE Standards dealing with significant hazards associated with posture and movement space are listed in
Annex A, see Table A.4.
5.3.2.4 Work rate and pattern
The work rate is a flow that describes the number of pieces per time unit measured at one operator’s
working station. There are benefits in providing the operator with some control over this rate although
this is clearly not always possible (for example in complex production lines involving several operators
working at different stages in the process). When non-adjustable by the operator(s), there is more
potential for the work rate imposed by the machine to cause problems, either because of the rate itself,
or due to the absence of personal control.
The most common types of harm when the physical work rate is too high and/or not controllable by the
operator and if recovery periods are absent or too rare, are musculoskeletal disorders (see 4.3.4), and
psychological stress (see 4.3.5).
In addition to potential physical work rate hazards, the designer should also consider the mental or
cognitive demands placed on the operator such as information acquisition; cognitive processing and
decision making requirements.
Information will be presented to the operator through a number of sensory channels including sight,
hearing and touch as well as, less commonly, smell or taste. Visual information might be through
designed displays (e.g. conventional dials or human machine interface) as well as observing the position
and status of the machine or parts of the machine itself and its surroundings (sometimes referred to as
“real” displays). Similarly auditory information might comprise warnings or indicators incorporated
into the machine – or the sounds made by the machine itself.
This sensory information has to be mentally processed and evaluated, and the mental demands are
related to the number and the complexity of these operations.
Each single component of these various work rates is easily determinable (and often measurable).
However, the final work rate is sometimes more complex as it can result from the combination and
interaction of multiple demands. When these demands are perceived as too high by the operator, they
can lead to negative physical or psychological reactions.
NOTE Standards dealing with significant hazards associated with work rate and pattern are listed in
Annex A, see Table A.5.
5.3.2.5 Human error
If the ergonomic factors influencing attention and concentration is not taken into account by machinery
designers, the risk of unintended behaviour of the operator or reasonably foreseeable misuse of the
machine occurs (see also ISO 12100:2010).
Machinery operations which result in very rapid or highly repetitive cyclic operations can increase
the risk of human error. Similarly, operations requiring intense concentration or sustained attention
(including those involving very long cycle times) can also increase such risks.
NOTE 1 Lighting, climate, noise and odours are other factors that can affect concentration and lead to
human error.
The more effort (e.g. processing capacity) the operator expends on the task, the less capacity remains
available for other tasks or circumstances that may demand attention leading to human error.
Vigilance requires attention and describes an individual’s state of alertness, watchfulness and
preparedness to attend to critical information that is not yet present. Vigilance decreases the longer the
period of supervisory duty (the decline begins to be evident after the first 30 min).
Attention and vigilance are not constant and may be impacted by environmental factors such as noise
and temperature.
NOTE 2 In this clause, it will be assumed that the term vigilance corresponds to a sustained concentration
ability.
Task factors such as frequency of signals can affect performance on attention and vigilance tasks. A
low number of critical signals significantly reduces performance (expressed in reaction time) during a
vigilance task. More non-critical signals per minute results in greater distraction and greater difficulty
in identifying critical signals.
NOTE 3 Standards dealing with significant hazards associated with human error are listed in Annex A, see
Table A.6.
5.3.2.6 Operator/machine interface
The operator/machine interface is mainly made up of control devices and displays which provide ways
of controlling what the machine does and provide the means for the operator to get information on the
status of the machine. Failure to adequately consider the design of the interface can mean a machine
is difficult to operate correctly and this can result in errors. The physical characteristics - shape, size,
placement, etc. are important; as is the way the control devices and displays have to be used. Control
devices and displays that are easy to use and understand are more likely to be used properly and less
likely to give rise to sign
...
TECHNICAL ISO/TR
REPORT 22100-3
First edition
2016-10-01
Safety of machinery — Relationship
with ISO 12100 —
Part 3:
Implementation of ergonomic
principles in safety standards
Sécurité des machines — Relation avec l’ISO 12100 —
Partie 3: Mise en oeuvre des principes ergonomiques dans les normes
de sécurité
Reference number
©
ISO 2016
© ISO 2016, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
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ii © ISO 2016 – All rights reserved
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Strategy for risk assessment and risk reduction in relation to ergonomic hazards .2
4.1 General . 2
4.2 Significant ergonomic hazards in relation to ISO 12100 . 4
4.3 Potential consequences . 4
4.3.1 General. 4
4.3.2 Discomfort . 4
4.3.3 Fatigue . 5
4.3.4 Musculoskeletal disorders . 5
4.3.5 Stress . 6
4.3.6 Human error . 7
5 Incorporating ergonomics into the risk assessment process . 8
5.1 Information for risk assessment . 8
5.1.1 General. 8
5.1.2 Information for establishing assessment criteria . 8
5.2 Determination of limits of machinery (user aspects) . 9
5.3 Hazard identification . 9
5.3.1 General concept for identifying ergonomic hazards . 9
5.3.2 Determination of hazards based on essential characteristics and
capabilities of intended operator population . 9
5.4 Risk estimation .13
5.4.1 General.13
5.4.2 Risk estimation tools .13
5.5 Risk evaluation .13
5.5.1 General.13
5.5.2 Evaluating the risk reduction achieved by the application of
ergonomic principles .13
5.5.3 Comparison of ergonomic risks .14
6 Risk reduction — Design guidance .14
6.1 General .14
6.2 Risk reduction — Human variability .14
6.3 Risk reduction — Posture and movement space .15
6.4 Risk reduction — Work rate and pattern .16
6.5 Risk reduction — Human error .16
6.6 Risk reduction — Operator/machine interface .17
6.7 Risk reduction — Workplace environment .18
6.7.1 General.18
6.7.2 Visual factors .18
6.7.3 Auditory factors .19
6.7.4 Vibration factors.19
6.7.5 Thermal factors .19
7 Verification of safety requirements .19
Annex A (informative) Standards dealing with ergonomics relevant to machinery design .20
Annex B (informative) Work system and machinery design .24
Annex C (informative) Ergonomics standards for specific applications .30
Annex D (informative) Example of part of the implementation of the ergonomic factors .31
Bibliography .35
iv © ISO 2016 – All rights reserved
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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment,
as well as information about ISO’s adherence to the World Trade Organization (WTO) principles in the
Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html
The committee responsible for this document is ISO/TC 199, Safety of machinery.
ISO/TR 22100 consists of the following parts, under the general title Safety of machinery — Relationship
with ISO 12100:
— Part 1: How ISO 12100 relates to type-B and type-C standards
— Part 2: How ISO 12100 relates to ISO 13849-1
— Part 3: Implementation of ergonomic principles in safety standards
Introduction
The primary purpose of this document is to provide designers with an overall framework and guidance
for decisions about ergonomic aspects during the development of machinery, to help them design
machines that are safe for their intended use. As mentioned in ISO 12100:2010, 6.2.8, failure to follow
ergonomic principles in design can result in the inadequate adaptation of machines to the capacities
and skills of the intended user population and hence place their health or safety at risk.
ISO 12100 describes an iterative process to reduce risks. This document describes the main ergonomic
factors influencing the safety of machinery and gives a framework for incorporating them into this
design process.
Mental (cognitive) aspects are also to be considered. For example, machines which are operated in an
inappropriate manner or whose control devices are not clearly identifiable can lead to human error.
This document is intended to guide users to make effective use of ergonomics standards within the
context of machinery design.
This document will help both ergonomics and machinery standards writers to incorporate the structure
specified in ISO Guide 78.
vi © ISO 2016 – All rights reserved
TECHNICAL REPORT ISO/TR 22100-3:2016(E)
Safety of machinery — Relationship with ISO 12100 —
Part 3:
Implementation of ergonomic principles in safety
standards
1 Scope
This document describes the main ergonomic risk factors influencing the safety of machinery and
gives a framework for incorporating them into the design of machines by the integration of important
ergonomic principles relating to:
— avoiding stressful postures and movements during use of the machine;
— designing machines, and more especially hand-held and mobile machines, which can be operated
easily;
— avoiding as far as possible noise, vibration, thermal effects;
NOTE 1 The health effects of noise, vibration and adverse thermal conditions are well-known and are not
addressed here. However environmental factors can interact with machine design and risks arising from such
influences are addressed in this document.
— avoiding linking the operator’s working rhythm to an automatic succession of cycles;
— providing local lighting on or in the machine;
NOTE 2 Lighting of the machine or of the surrounding workplace by the machine can have a significant impact
on the safety of machine operation and this risk is addressed by this document.
— selecting, locating and identifying manual controls (actuators) so that they are clearly visible and
identifiable and appropriately marked where necessary;
— selecting, designing and locating indicators, dials and visual display units.
The approach is based on ISO 12100 with its iterative process to identify significant hazards and
reduce risks.
Relevant steps of this iterative process have been adapted to include ergonomic principles, and practical
guidance is given to apply standards dealing with ergonomics which are relevant for machinery design.
This document is intended for use by standards writers and designers of machinery. It can be used
when no relevant C-type standards are available.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 12100:2010, Safety of machinery — General principles for design — Risk assessment and risk reduction
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 12100 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at http://www.iso.org/obp
3.1
ergonomics
study of human factors
scientific discipline concerned with the understanding of interactions among human and other elements
of a system, and the profession that applies theory, principles, data and methods to design in order to
optimize human well-being and overall system performance
[SOURCE: ISO 6385:2004, 2.3]
3.2
ergonomic hazard
hazard arising from the failure to adequately consider ergonomic principles in machine design
Note 1 to entry: For ergonomic hazards see also ISO 12100:2010, Table B.1, No. 8.
4 Strategy for risk assessment and risk reduction in relation to ergonomic hazards
4.1 General
The risk assessment process carried out by designers in accordance with ISO 12100:2010, Clause 5,
provides information that is required for the risk evaluation through which decisions can be taken
whether risk reduction is necessary. These decisions have to be supported by a qualitative or, where
appropriate, a quantitative estimation of the risk identified. This is to be met by taking into account
both the risks normally considered in machine design, and those arising from failing to consider the
principles of ergonomics.
Figure 1 shows a schematic representation of the risk reduction process, derived from ISO 12100:2010,
which illustrates how ergonomics can be integrated into the iterative three-step risk reduction process
(including references to the relevant clauses in this document).
2 © ISO 2016 – All rights reserved
Figure 1 — Illustration of the integration of ergonomics into the iterative three-step design
process for risk reduction (based on ISO 12100:2010, Figure 1)
4.2 Significant ergonomic hazards in relation to ISO 12100
Designs which do not take ergonomics into account can have potential consequences such as discomfort,
fatigue, musculoskeletal disorders, stress and human error (see 4.3). When these are identified as being
associated with the machine, they are relevant ergonomic hazards. Consequences such as discomfort
and fatigue can also lead indirectly to human error. If the potential consequences require specific action,
then these are significant hazards and are as important as those arising from mechanical, electrical
and other hazards (see ISO 12100:2010, Table B.1).
NOTE 1 Discomfort and fatigue are relevant warning signals, as they can lead to occupational disease or to
accidents and can influence performance and quality.
NOTE 2 The term ergonomic hazard is used in ISO 12100 to describe hazards resulting from the failure to
adequately consider ergonomics during the design process. For consistency this term is therefore retained in this
document.
Table 1 shows an example comparing mechanical hazards with ergonomic hazards.
Table 1 — Comparison of mechanical and ergonomic aspects of hazards
Work task: load/unload a machine
Location of hazard: machine loading area
Hazards arising from the failure
Mechanical aspects Ergonomic aspects
to adequately consider
Origin of hazard Sharp edge Sustained awkward posture
Factors influencing the risk Surface characteristics Space for movement restricted
Potential consequences Cutting Discomfort/Fatigue
Harm Injury, pain, bleeding Back pain, musculoskeletal disorders
Severity of harm Light to serious damage to health Light to serious damage to health
(reversible or chronic)
4.3 Potential consequences
4.3.1 General
Taking ergonomic principles into account in designing machinery helps to reduce the mental or physical
load on the operator. In turn this reduces strain and improves efficiency. It is important to consider
these principles when allocating functions to operator and machine in the basic design.
As outlined in ISO 12100, failure to consider these principles can have potential consequences for
the health, safety and performance of the operator. Table B.1 of ISO 12100:2010 lists some of these
consequences, which are described below.
4.3.2 Discomfort
Discomfort refers to a lack of comfort, to a mental or physical uneasiness that is less intense and less
localized than pain. On the contrary, comfort gives or brings aid, support, satisfaction. Comfort refers
to a condition furnishing mental and/or physical ease. Sustained discomfort can lead to
— lack of attention or concentration (distraction),
— ill-health,
— absenteeism,
— decreased productivity — both qualitatively (with more discarded items) and quantitatively, and
— accidents.
4 © ISO 2016 – All rights reserved
Important aspects contributing to discomfort are
— awkward postures or sustained (static) postures,
— heavy physical work,
— repetitive movements,
— accessibility e.g. reaching distances,
— visual comfort, e.g. lines of sight, colour, visibility, light intensity and direction, viewing distances,
— surface contact e.g. shape, temperature, ease of contact,
— vibration (whole body and hand-arm),
— noise e.g. intensity, frequency, duration, pattern,
— climate/environment e.g. air temperature, wind speed (draught), relative humidity, clothing,
— odours e.g. fumes,
— inadequate cooperation or communication between operators during machine operation,
— balance between activity and inactivity; between vigilance and inattentiveness.
4.3.3 Fatigue
Fatigue is a state of impaired performance capability which can result from current or preceding
physical and/or mental activities. Fatigue can be physical or mental, general or local. The extent of
any fatigue depends on the intensity, duration and temporal pattern of these activities. Recovery from
fatigue requires rest periods with sufficient time for recuperation.
Important aspects contributing to fatigue are:
— type of workload, e.g. mental or physical;
— intensity of the workload, e.g. weight to be moved, complexity of information to be processed;
— repetitiveness of task components (highly repetitive tasks can be more fatiguing);
— time for recovery e.g. rest breaks.
NOTE As well as variation in mental and physical capabilities between different operators, the capabilities
of an individual operator and therefore their susceptibility to fatigue and other effects will vary over time.
4.3.4 Musculoskeletal disorders
Musculoskeletal disorders can be either acute or chronic. Acute disorders usually arise from some
form of muscle overload, with work which is either too demanding, or with other characteristics such
as sudden onset, which can tear or strain muscles or other soft tissue structures.
Chronic disorders usually arise from sustained or repeated demands which exceed the body’s
recovery and repair mechanisms. In some instances, unaccustomed activities create a hazard and an
introductory or learning period can be beneficial.
Some disorders can be either acute or chronic in origin. For example, some tendon problems can arise
from a short-term overload (acute) or a more sustained period of repeated activity.
Static loading (force application without movement) can also be problematic as muscle movement is an
essential part of the recovery and repair process.
Important aspects contributing to musculoskeletal disorders:
— force requirements (are related to the size of the body part involved, with larger muscles being
generally capable of higher forces);
— frequency of movements (smaller body parts such as fingers are naturally better suited to rapid
movements than larger joints such as the shoulder);
— duration of force application (the greater the force, the less time it can be sustained for, especially
without movement);
— position of body parts – posture - (body parts are more resilient when working close to their
anatomical neutral position, such as with the arms by the side rather than raised above the
shoulders);
— range of joint movement (as a rough guide, remaining within the middle 50 % of the range of
movement is preferable and the more extreme a movement or posture the more strain will be
experienced).
NOTE External environmental loads, such as vibration (hand-arm or whole-body) or extremes of
temperature may need to be taken into account. This document does not cover noise and vibration requirements.
4.3.5 Stress
4.3.5.1 General
The terminology relating to “stress” is often both confused and confusing. In some instances, the term
is used in the equivalent manner to the engineering use of the term, to reflect the loads placed on a
person (with the outcome regarded as ‘strain’). In others, these are referred to as stressors, with the
impact regarded as stress. Still others term the loads as pressure – again with stress as the potential
outcome.
When used in the engineering sense, the term is essentially neutral and stress can be beneficial or
harmful depending upon its characteristics. In other instances however, stress as an outcome is, by
definition an adverse consequence.
Both fatigue and discomfort, addressed above, can be caused by physical and psychological stressors.
However, although the volume of work can be a contributor to psychological stress it is more usually
psychological factors which combine to give rise to the negative outcome. For this reason in some
countries, to avoid any confusion, the term “psychological stress” is used instead.
NOTE 1 Psychological stressors can also aggravate existing fatigue and discomfort.
NOTE 2 Psychological stress is sometimes referred to as mental stress.
4.3.5.2 Psychological stress
In a safety of machinery context, it is likely to be issues such as the complexity and variability of the
tasks required of operators and others, together with cognitive factors such as requirements for
sustained attention and the probability and consequences of errors which contribute to any risk.
Important aspects contributing to psychological stress, which can be influenced by the design of the
machine, include
— complexity of task,
— variability of task,
— time constraints on performance,
— cognitive resources required,
6 © ISO 2016 – All rights reserved
— multitasking vs. serial task performance,
— probability of errors,
— consequences of errors,
— design of interfaces (e.g. displays, signals and controls),
— requirements for sustained attention,
— repetitiveness of task performance,
— intensity of workload, and
— temporal pattern of workload.
The general factors which contribute to the overall burden of psychological stress can be grouped into
six broad categories:
1) demands (not being able to cope with the demands of the job);
2) control (not having sufficient influence over how work is done);
3) support (not having sufficient support from colleagues and superiors);
4) relationships (being subjected to unacceptable behaviours);
5) role (not understanding roles and responsibilities);
6) change (not being involved and informed in organisational changes).
However, central to the concept of psychological stress, and a major mediating influence over whether
the demands placed on an individual become excessive, is the idea of the individual ‘coping’ with
the demands placed upon them. Thus, psychological stress develops when work demands of various
types and combinations exceed the person’s capacity and capability to cope. The consequences can be
considerable including poor mental wellbeing, anxiety or depression as well as contributing to physical
ill-health.
4.3.6 Human error
Human error, which can be expressed as a discrepancy between the human action taken or omitted,
and that intended or required is a very complex field, with many different approaches to defining
and classifying errors. In a safety of machine design context, the focus turns to the potential for
human error by the designer, in failing to adequately ensure that controls or displays can be clearly
and unambiguously identified and operated correctly in accordance with operator expectations
(stereotypes).
In essence, errors can occur when a person does something he or she should not (e.g. operating the
wrong control device) or does not do something he/she should (e.g. spot a warning signal). However, the
complexities increase when the possibilities are explored further. Thus, was the wrong control device
activated, the right one operated wrongly, the right one operated at the wrong time, and so on. Do the
consequences arise from the failure to operate the right control device — or the operation of the wrong
one? The likelihood of error is also influenced by additional factors such as work demands or pressures,
sustained vigilance, monotony, etc.
Some important machine design aspects contributing to human error are
— selection of inappropriate display designs (e.g. digital or analogue displays),
— inappropriate control design (e.g. small devices to be operated by gloved hands),
— inappropriate control-response relationships (e.g. direction of control movement in relation to the
movement of the machine),
— poorly identified control devices or displays (e.g. inadequate labelling, wrong colour coding),
— poor layout of control devices (e.g. insufficient space between devices), and
— poor layout of displays (e.g. viewing angle from operating position).
This list presents aspects through which poorly considered design can increase the risk of human error
and avoiding these through good design will improve machine safety.
5 Incorporating ergonomics into the risk assessment process
5.1 Information for risk assessment
5.1.1 General
5.2 to 5.5 describe the steps for incorporating ergonomics into the risk assessment process in
accordance with ISO 12100:2010, Clause 5.
Because ergonomics deals with interactions between people and other elements of a system, special
attention should be drawn to the overall work system (see ISO 6385), which is the basis for the
determination of the limits of the machinery [see ISO 12100:2010, 5.2 d) and 5.3].
5.1.2 Information for establishing assessment criteria
Establishing assessment criteria requires knowledge of the technical design of the machine and the
characteristics and capabilities of the intended operator population including their experience and
training with similar machines.
In order to perform an adequate risk assessment, the following basic parameters of the machine should
be defined:
a) functions and their limits;
b) human interfaces with different parts of the machine.
The determination of the characteristics of the operator population is based on
— physical limitations (stature, reach, strength, vision, etc.), and
— mental ability (education, training, experience, etc.).
Essential information for risk assessment is required relating to
— the functionality of the machine,
— the allocation of function between manual and automated processes,
— the job (task elements),
— the human/machine interface characteristics,
— where the machine will be installed,
— how the machine will be used (including maintenance) and removed,
— information for training of personnel, and
— production and maintenance procedures.
8 © ISO 2016 – All rights reserved
5.2 Determination of limits of machinery (user aspects)
Risk assessment starts with the determination of the limits of the machinery, which includes taking
into account the characteristics and capabilities of the intended operator population.
NOTE The limits of machinery can be part of the contract between the supplier and user of a machine.
5.3 Hazard identification
5.3.1 General concept for identifying ergonomic hazards
Human error, musculoskeletal disorders, stress, discomfort and fatigue are potential consequences
arising from ergonomic hazards which result from the failure to adequately consider ergonomics
during the design process [see ISO 12100:2010, 5.4 a) and 5.4 c)].
Important ergonomic risk factors to be taken into account include
— human variability,
— posture and movement space,
— work rate and pattern,
— human error,
— operator/machine interface, and
— workplace environment.
Detailed information relating to the determination of hazards based on the essential characteristics
and capabilities of the intended operator population is given in 5.3.2.1 to 5.3.2.7.
5.3.2 Determination of hazards based on essential characteristics and capabilities of intended
operator population
5.3.2.1 General
Particular attention is drawn to the following seven ergonomic aspects of machinery design (see
ISO 12100:2010, 6.2.8) that should be considered when identifying hazards:
a) forces, postures and movements during use of the machine;
b) operability or controllability of the machine, especially hand-held and mobile machines;
c) environmental effects of the machine and its surroundings (e.g. noise, vibration, thermal);
d) operator’s working rhythm linked to an automatic succession of cycles;
e) integral task lighting (on or in the machine);
f) selection, design and location of control devices;
g) selection, design and location of indicators, dials and visual display units.
In order to help address these aspects, this document describes six important ergonomic risk factors
that need to be considered. Each factor is relevant to one or more of the above ergonomic aspects. The
main links between these factors (1 through 6) and the aspects a, b, c, d, e, f and g relating to them are
described in the text below and summarized in Table 2.
Table 2 — Link between ergonomic risk factors and ergonomic aspects
Ergonomic risk factor Ergonomic aspects of machinery design
1) Human variability a) Forces, postures and movements during use of the machine
b) Operability or controllability of the machine, especially hand-held and mo-
bile machines
2) Posture and movement a) Forces, postures and movements during use of the machine
space
b) Operability or controllability of the machine, especially hand-held and mo-
bile machines
d) Operator’s working rhythm linked to an automatic succession of cycles
3) Work rate and pattern d) Operator’s working rhythm linked to an automatic succession of cycles
4) Human error c) Environmental effects of the machine and its surroundings (e.g. noise, vibra-
tion, thermal)
e) Integral task lighting (on or in the machine)
f) Selection, design and location of control devices
g) Selection, design and location of indicators, dials and visual display units
5) Operator/machine f) Selection, design and location of control devices
interface
g) Selection, design and location of indicators, dials and visual display units
6) Workplace environment c) Environmental effects of the machine and its surroundings (e.g. noise, vibra-
tion, thermal)
e) Integral task lighting (on or in the machine)
NOTE General ergonomic design standards are listed in Annex A, see Table A.1.
5.3.2.2 Human variability
Human beings differ widely in their attributes. When addressing this variability in the design process,
the main factors to be taken into account are physical dimensions, strength (and stamina). These should
be considered by taking into account gender, body dimensions and build, age, body weight and physical
strength and disabilities. Psychological or cognitive factors may also need to be considered depending
on the nature and function of the machine being designed (e.g. skills and experience).
Body dimensions can vary between different populations, more usually between countries from different
parts of the world but, particularly in some larger or more diverse countries, from region to region.
Age-related adverse effects can be partly compensated by training and/or assistive technology. Other
adverse effects of age can be compensated by operators adopting different strategies. Older people
generally have more experience and higher decision-making capabilities than their younger peers.
Individual performance (e.g. vigilance) and capacity will vary not only with age, but also throughout a
working day with generally poorer cognitive performance as fatigue develops.
NOTE 1 In particular instances it can be appropriate to consider health-related impairments, e.g. reduction in
grip strength due to osteoarthritis, operators with pacemakers etc.
NOTE 2 The impact of some aspects of human variability can be modified or offset. For example: strength can
be increased (by physical training); additional skills can be gained.
NOTE 3 Standards dealing with significant hazards associated with human variability are listed in Annex A,
see Tables A.2 and Table A.3
5.3.2.3 Posture and movement space
The space necessary for the operator(s) postures and movements needed for machine operation should
be taken into account in any design process.
10 © ISO 2016 – All rights reserved
Sustained working postures, such as sitting, standing, trunk bending, kneeling; together with tasks
requiring the arms to be used above shoulder height can be critical if the posture is sustained or
repeated for long periods. Twisting movements or extreme positions of the hand or arm, as well as
repetitive body movements, especially where they involve the application of forces, should be avoided.
Sufficient space for movement is one of the basic principles in machinery design to prevent accidents
and occupational diseases e.g. musculoskeletal disorders. Restricting movement can potentially be as
harmful as requiring too great a range of movement. Appropriate body movements are indispensable to
avoid physical stress and strain.
Anthropometric data for the intended operating population and knowledge of their work tasks are
therefore important factors in identifying potential hazards arising from any mismatch between the
dimensions of the human body and the size and dimensions allowed for in any machine design.
It should be remembered that worker’s tasks are not limited to regular machine operating functions.
Maintenance, troubleshooting, repairing and installing machinery are important tasks to consider and
can give rise to risks. The need for access to danger zones for maintenance, lubrication and setting
should be minimized. However, if needed, factors such as the access space and postures required to
reach machine parts for these tasks should be taken into account during the design process.
NOTE Standards dealing with significant hazards associated with posture and movement space are listed in
Annex A, see Table A.4.
5.3.2.4 Work rate and pattern
The work rate is a flow that describes the number of pieces per time unit measured at one operator’s
working station. There are benefits in providing the operator with some control over this rate although
this is clearly not always possible (for example in complex production lines involving several operators
working at different stages in the process). When non-adjustable by the operator(s), there is more
potential for the work rate imposed by the machine to cause problems, either because of the rate itself,
or due to the absence of personal control.
The most common types of harm when the physical work rate is too high and/or not controllable by the
operator and if recovery periods are absent or too rare, are musculoskeletal disorders (see 4.3.4), and
psychological stress (see 4.3.5).
In addition to potential physical work rate hazards, the designer should also consider the mental or
cognitive demands placed on the operator such as information acquisition; cognitive processing and
decision making requirements.
Information will be presented to the operator through a number of sensory channels including sight,
hearing and touch as well as, less commonly, smell or taste. Visual information might be through
designed displays (e.g. conventional dials or human machine interface) as well as observing the position
and status of the machine or parts of the machine itself and its surroundings (sometimes referred to as
“real” displays). Similarly auditory information might comprise warnings or indicators incorporated
into the machine – or the sounds made by the machine itself.
This sensory information has to be mentally processed and evaluated, and the mental demands are
related to the number and the complexity of these operations.
Each single component of these various work rates is easily determinable (and often measurable).
However, the final work rate is sometimes more complex as it can result from the combination and
interaction of multiple demands. When these demands are perceived as too high by the operator, they
can lead to negative physical or psychological reactions.
NOTE Standards dealing with significant hazards associated with work rate and pattern are listed in
Annex A, see Table A.5.
5.3.2.5 Human error
If the ergonomic factors influencing attention and concentration are not taken into account by
machinery designers, the risk of unintended behaviour of the operator or reasonably foreseeable
misuse of the machine occurs (see also ISO 12100:2010).
Machinery operations which result in very rapid or highly repetitive cyclic operations can increase
the risk of human error. Similarly, operations requiring intense concentration or sustained attention
(including those involving very long cycle times) can also increase such risks.
NOTE 1 Lighting, climate, noise and odours are other factors that can affect concentration and lead to
human error.
The more effort (e.g. processing capacity) the operator expends on the task, the less capacity remains
available for other tasks or circumstances that may demand attention leading to human error.
Vigilance requires attention and describes an individual’s state of alertness, watchfulness and
preparedness to attend to critical information that is not yet present. Vigilance decreases the longer the
period of supervisory duty (the decline begins to be evident after the first 30 min).
Attention and vigilance are not constant and can be impacted by environmental factors such as noise
and temperature.
NOTE 2 In this clause, it will be assumed that the term vigilance corresponds to a sustained concentration
ability.
Task factors such as frequency of signals can affect performance on attention and vigilance tasks. A
low number of critical signals significantly reduces performance (expressed in reaction time) during a
vigilance task. More non-critical signals per minute results in greater distraction and greater difficulty
in identifying critical signals.
NOTE 3 Standards dealing with significant hazards associated with human error are listed in Annex A, see
Table A.6.
5.3.2.6 Operator/machine interface
The operator/machine interface is mainly made up of control devices and displays which provide ways
of controlling what the machine does and provide the means for the operator to get information on the
status of the machine. Failure to adequately consider the design of the interface can mean a machine is
difficult to operate correctly and this can result in errors. The physical characteristics — shape, size,
placement, etc. — are important, as is the way in which the control devices and displays have to be used.
Control devices and displays that are easy to use and understand are more likely to be used properly
and less likely to give rise to significant hazards. For example control devices that require excessive
force can cause muscle fatigue, and/or be misused; displays that are difficult to interpret or are not
very vis
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