EN ISO 19734:2021

SLOVENSKI STANDARD
01-julij-2021
Varovanje oči in obraza - Navodilo za izbiro, uporabo in vzdrževanje (ISO
19734:2021)
Eye and face protection - Guidance on selection, use and maintenance (ISO
19734:2021)
Augen- und Gesichtsschutz - Leitfaden zur Auswahl, Anwendung und Instandhaltung
(ISO 19734:2021)
Protection des yeux et du visage - Lignes directrices pour le choix, l’utilisation et
l’entretien (ISO 19734:2021)
Ta slovenski standard je istoveten z: EN ISO 19734:2021
ICS:
13.340.20 Varovalna oprema za glavo Head protective equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 19734
EUROPEAN STANDARD
NORME EUROPÉENNE
March 2021
EUROPÄISCHE NORM
ICS 13.340.20
English Version
Eye and face protection - Guidance on selection, use and
maintenance (ISO 19734:2021)
Protection des yeux et du visage - Lignes directrices Augen- und Gesichtsschutz - Leitfaden zur Auswahl,
pour le choix, l'utilisation et l'entretien (ISO Anwendung und Instandhaltung (ISO 19734:2021)
19734:2021)
This European Standard was approved by CEN on 2 March 2021.

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 CEN-CENELEC Management Centre 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 CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 19734:2021 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 19734:2021) has been prepared by Technical Committee ISO/TC 94 "Personal
safety -- Personal protective equipment" in collaboration with Technical Committee CEN/TC 85 “Eye
protective equipment” the secretariat of which is held by AFNOR.
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 September 2021, and conflicting national standards
shall be withdrawn at the latest by September 2021.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 19734:2021 has been approved by CEN as EN ISO 19734:2021 without any modification.

INTERNATIONAL ISO
STANDARD 19734
First edition
2021-02
Eye and face protection — Guidance
on selection, use and maintenance
Protection des yeux et du visage — Lignes directrices pour le choix,
l’utilisation et l’entretien
Reference number
ISO 19734:2021(E)
©
ISO 2021
ISO 19734:2021(E)
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved

ISO 19734:2021(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General . 2
4.1 Structure of the human eye . 2
4.2 Hazards and risks to the eye and face . 3
4.2.1 Surrounding structures of the eye . 3
4.2.2 Peri-orbital skin . 4
4.2.3 Tears . 4
4.2.4 Cornea and conjunctiva . . 4
4.2.5 Iris and lens . 4
4.2.6 Retina . 5
4.2.7 Optic nerve . 5
4.2.8 Choroid and retinal pigment epithelium. 5
4.3 The eye's defence system . 5
4.4 Colour perception . 7
5 Hazards and their consequences . 8
5.1 General hazards . 8
5.1.1 Mechanical hazards . 8
5.1.2 Chemical hazards. 9
5.1.3 Radiation hazards .10
5.1.4 Biological hazards .11
5.1.5 Convection heat .12
5.2 Application specific hazards.12
5.2.1 Laser hazards .12
5.2.2 Welding hazards .13
5.2.3 Electric arc hazards .14
5.2.4 Glass blowing hazards .14
6 Control of eye and face hazards .15
6.1 General .15
6.2 Screens .16
6.2.1 General.16
6.2.2 Recommended materials for screens .17
6.2.3 Selection of light-transmitting screens and curtains for arc welding operations 17
6.2.4 Illumination of the work area .17
6.3 Exhaust systems .17
6.4 Other methods .17
7 Selection and use of personal protective equipment (PPE) .18
7.1 General .18
7.2 Types of eye and face protectors .18
7.2.1 General.18
7.2.2 Selection process .20
7.2.3 Eye and face protection for those requiring vision correction .26
7.2.4 Material choice .27
7.2.5 Comfort, vision and fit .28
7.2.6 Application based selection.29
7.3 Checking the fit .39
7.3.1 Fit, comfort and compliance .39
7.3.2 Ensuring compliance with an eye protection programme .40
ISO 19734:2021(E)
8 Care and maintenance .40
8.1 Hygiene and cleaning .40
8.2 Replacement of eye protectors.41
9 Compatibility .41
9.1 General .41
9.2 Eye protectors and respirators .42
9.3 Eye protectors and protective earmuffs .42
9.4 Helmet mounted face shields .42
9.5 Face shields and respirators .42
9.6 Eyewear with half-mask respirators .42
10 Eye and face protector marking .42
11 Special requirements for working conditions (e.g. hot, humid, dusty, fog, abrasion) .43
Annex A (informative) Electric arc protective equipment combinations .45
Annex B (informative) Marking of laser eye protectors .47
Bibliography .49
iv © ISO 2021 – All rights reserved

ISO 19734:2021(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.
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 of the voluntary nature of standards, 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 www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 94 Personal safety — Personal protective
equipment, Subcommittee SC 6 Eye and face protection, in collaboration with the European Committee
for Standardization (CEN) Technical Committee CEN/TC 85, Eye-protective equipment, in accordance
with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
ISO 19734:2021(E)
Introduction
This document is intended to provide guidance on how to select, use and maintain eye and face
protectors. A workplace eye and face safety programme should be introduced and a hierarchy of control
followed where workers are exposed to a recognised risk of injury to the eyes and/or face. Examples of
areas and processes where eye and/or face hazards may exist are shown in Tables 2, 4 and 5.
The aim of an eye and face safety programme is to protect the eyes and face of the worker through
the process of elimination or control of hazards and, where necessary, the wearing of appropriate
protection.
While responsibility for the successful implementation of an eye and face safety programme rests with
senior management, every effort is required to secure the participation and involvement of employees
or their representatives in all phases of the programme. Experience has shown that programmes
lacking this involvement have less chance of success.
A critical examination of working conditions, particularly lighting, layout and planning of buildings and
processes, forms a necessary part of an eye and face safety programme.
Selection of a suitable programme may be assigned to safety personnel within the organisation or
advice may be sought from outside sources. Elements that have been found in successful eye and face
safety programmes include the following:
a) An assessment of hazards.
b) Determination of workplace hazard areas.
c) Elimination or confinement of hazards (where possible).
d) Vision screening.
e) Referral for optometric, ophthalmological examination or both, where necessary.
f) The universal wearing of suitable eye and face protectors for those persons at risk.
g) Educational campaigns on eye safety.
Eye and face protectors are items of personal protective equipment (PPE) intended to prevent the
harmful effects that physical (e.g. flying particles, dust, splashing and molten materials), optical (e.g.
solar and artificial radiation and high intensity radiation generated during operations such as welding
and furnace work), chemical (e.g. pressurised materials, harmful gases, vapours and aerosols) and
biological hazards may have to the eye and face.
For eye and face protectors to be effective they should be used at all times when the user is in a
potentially hazardous environment. When selecting eye and face protectors, attention should be given
to factors influencing comfort and user preference.
Those involved in selling eye and face protectors to the general public for use in non-workplace settings
should adhere to the principles and guidance in this standard to ensure that users of personal protective
equipment are fully informed about making the safest choice for a particular task and environment
as well as how to use the protective equipment in the safest manner. This should also apply to those
businesses that hire out power equipment. Safety guidance based on this document should be provided
to prospective customers to ensure that they select and use the correct protective equipment to reduce
the risk of eye and face injury.
vi © ISO 2021 – All rights reserved

INTERNATIONAL STANDARD ISO 19734:2021(E)
Eye and face protection — Guidance on selection, use and
maintenance
1 Scope
This document gives guidance to specifiers and users on the control of eye and face hazards including
physical, mechanical, chemical, optical radiation and biological and on the selection, use and
maintenance of eye and face protectors.
This document applies to
— occupational use,
— tasks that are performed similarly to those in an occupation but not in the workplace, e.g. "do-it-
yourself", and
— schools, educational and research establishments.
This document does not apply to eye and face protection for
— ionizing radiation,
— low frequency radio waves,
— microwaves,
— sports or vehicular usage, and
— sunglasses for general (not occupational) use – see ISO 12312-1.
NOTE The ISO 18527 (all parts) sets requirements for eye protectors for some sports.
Brief advice on protection when using lasers is included but for detailed advice, see IEC/TR 60825-14.
This document is neither a whole nor partial substitute for risk assessment, which is an essential part
of any eye and face protection programme.
Although this document has been written to help specifiers and users, any recommendations in this
document are to be interpreted as guidance only and not intended to replace any national regulatory
requirements. Risk assessment is the sole responsibility of the employer and not the PPE manufacturer
or its authorised representative.
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 4007, Personal protective equipment — Eye and face protection — Vocabulary
3 Terms and definitions
1) 2)
For the purposes of this document, the terms and definitions given in ISO 4007 and the following apply .
1)  The terms and definitions for risk and hazard have been included here for the reader's convenience.
2)  The abbreviation PPE means personal protective equipment.
ISO 19734:2021(E)
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
NOTE ISO/IEC Guide 51:2014, Clause 4, states: The term “safe” is often understood by the general public as
the state of being protected from all hazards. However, this is a misunderstanding: “safe” is rather the state of
being protected from recognized hazards that are likely to cause harm. Some level of risk is inherent in products
or systems. The use of the terms “safety” and “safe” as descriptive adjectives is avoided when they convey no
useful extra information. In addition, they are likely to be misinterpreted as an assurance of freedom from risk.
The recommended approach is to replace, wherever possible, the terms “safety” and “safe” with an indication of
the objective – for example, the phrase “protective spectacles” should be used in preference to “safety spectacles”.
3.1
hazard
potential source of harm
[SOURCE: ISO/IEC Guide 51:2014, 3.2]
3.2
risk
combination of the probability of occurrence of harm and the severity of that harm
Note 1 to entry: Note 1 to entry: The probability of occurrence includes the exposure to a hazardous situation,
the occurrence of a hazardous event and the possibility to avoid or limit the harm.
[SOURCE: ISO/IEC Guide 51:2014, 3.9]
4 General
4.1 Structure of the human eye
See Figure 1.
2 © ISO 2021 – All rights reserved

ISO 19734:2021(E)
Key
1 eyelid 8 vitreous chamber (filled with vitreous humour)
2 iris 9 crystalline lens
3 pupil 10 optic nerve
4 anterior Chamber (filled with aqueous humour) 11 macular region of retina
5 cornea 12 pigment epithelium and choroid
6 ciliary muscle 13 sclera
7 retina
Figure 1 — Outline of the human eye (cross section)
a) Light emitted, transmitted or reflected by an object in the field of vision travels toward the eyes.
b) Light passes through the CORNEA (transparent “front window” of the eye), which provides two-
thirds of the focusing power of the eye.
c) The PUPIL (the opening at the centre of the pigmented IRIS) changes size to vary the amount of
light that reaches the retina.
d) The CRYSTALLINE LENS provides the remaining focusing power of the eye.
e) The RETINA (rear inner lining of the eye that contains light-sensitive and image processing cells
and nerve fibres) converts light into neural signals. The MACULAR region is located near the centre
of the retina and is dense with photoreceptors; its function is to process central vision in fine detail.
f) The OPTIC NERVE is the collection of nerve fibres that carry these signals to the brain.
4.2 Hazards and risks to the eye and face
4.2.1 Surrounding structures of the eye
The structures surrounding the eye, including the eyelids, skin, muscles and the orbital bones are
susceptible to permanent damage. Objects of sufficient energy can cause bone fracture, contusions,
lacerations and penetration of these tissues. Damage to the muscles and bones around the eye can
result in a temporary or permanent disruption to binocular vision.
ISO 19734:2021(E)
4.2.2 Peri-orbital skin
The skin of the eyelids is thinner than the skin in the rest of the body and is therefore more susceptible
to physical damage such as bruising and lacerations, while the geometry of the lower lid makes it more
vulnerable to UV radiation damage, including some skin cancers.
4.2.3 Tears
The lacrimal gland, which is situated in the orbit above and temporal to the eye, secretes the watery
content of tears. Tiny glands in the conjunctiva secrete mucous. Meibomium glands in the upper
(mainly) and lower lids secret an oily substance. These components combine into a structured layer
of tears. Tears drain down to the nose through the naso-lacrimal ducts (often called simply the "tear
ducts") that start as openings in the edges of the eyelids near the nose. The glands can be damaged
directly by chemicals. Chemicals can also be absorbed into the body through the conjunctiva, the nasal
mucosa or digestive system if washed through the tear ducts. Microorganisms may also enter the body
by this route.
4.2.4 Cornea and conjunctiva
The cornea is about 0,6 mm thick at its centre and is composed of several layers. The outermost layer
of the cornea, the epithelium, is highly sensitive to foreign bodies, including fine particles and dust,
that can irritate and damage it. The resulting discomfort and soreness can last from a few minutes
to several days. The epithelium regenerates very rapidly, so minor lesions heal quickly leaving no
permanent damage. Minor ingress of foreign matter can be readily dispersed by the tears whereas
larger amounts will require dispersal with a copious stream of water or other more intensive remedies
conducted within a specialized medical environment. Even minor damage to the epithelium may
facilitate infection which can result in clouding and permanent vision loss.
The main component of the cornea, about 90 % of its thickness, is the stroma. This relies on a very
regular structure for its transparency so that any physical damage results in scar tissue that is irregular
and, therefore, not transparent. Hence, more severe damage to the cornea that goes deeper than the
epithelium such as lacerations, penetration, etc, will give opaque scar tissue which can result in clouded
or permanent loss of vision.
Alkalis and strong acids will cause serious, often permanent, damage to the conjunctiva and cornea,
which could lead to blindness. Alkalis are particularly damaging to the surface of the eye, rapidly
causing irreversible damage. Conjunctivitis can also be caused by allergic reactions to many chemical
substances, pollens, and biological agents. Even minor splashes or a fine aerosol spray of such substances
can cause irritation.
The innermost layer of the cornea is a single layer of cells that form the endothelium. These cells do not
regenerate after damage, the remaining cells enlarge to spread out over the surface. If this number falls
below a threshold, the cornea becomes oedematous and is unable to maintain its transparency.
Exposure to sufficiently intense sources of infrared radiation from artificial sources can result in burns
to the cornea (IR-B and C), retina and the lens (IR-A). Exposure to sufficiently high levels of UV radiation
result in an acute painful inflammation of the epithelium of the cornea and conjunctiva. This acute
effect is typically associated with exposure to electric arc welding and is commonly known as arc-eye
or welder’s flash. Long term exposure to UV can also result in chronic conditions such as pinguecula
(a scar on the exposed conjunctival tissue nasally and temporally), pterygium (an abnormal mass of
thickened conjunctiva and blood vessel growth into the cornea, most frequently on the nasal side),
exposure keratitis (inflammation) and endothelial polymegethism (irregular cell sizes and shapes).
4.2.5 Iris and lens
Flying objects of sufficient mass and velocity can penetrate the cornea to injure the iris and the lens.
Blunt trauma, e.g. walking into objects or falling onto furniture, impact from a large object such as
a football or basketball, can result in damage to the iris, and can also cause cataract or subluxation
(displacement) of the lens. Physical damage to the lens and its associated muscles can result in
4 © ISO 2021 – All rights reserved

ISO 19734:2021(E)
permanent loss of focus and increased susceptibility to certain diseases e.g. glaucoma. Damage to the
iris can result in problems with light sensitivity (photophobia).
4.2.6 Retina
As well as being damaged by penetrating objects, the retina is also susceptible to blunt trauma to
the exterior of the eye. This can result in retinal detachment and visual field loss. Acute damage, i.e.
damage caused essentially immediately after an event rather than cumulatively, may be caused by high
intensity optical radiation, e.g. lasers or viewing the sun. Visible light, especially blue-light, can cause
photochemical damage within the light-sensitive cells of the retina. This painless loss of vision occurs
several hours after the injurious exposure and may take several months to recover; permanent vision
loss is possible. Some chemicals or medicines, e.g. drugs used to treat skin conditions, can photosensitize
the retina so that less UV radiation or visible light is needed to cause damage.
4.2.7 Optic nerve
Blunt trauma to the eye can also result in damage to the optic nerve.
Though rare, intra-orbital penetration of objects, between the eye and the orbital bones, can occur and
can result in damage to the optic nerve and the brain.
Exposure to certain chemicals can cause inflammation of the optic nerve, a condition known as optic
neuritis. In the longer term, this can lead to degenerative changes known as optic atrophy. The resulting
poor vision is often called “toxic amblyopia". This is more likely, however, to be caused by systemic
absorption, e.g. drinking methanol or inhaling lead-contaminated dust, than resulting from chemical
splashes in the eye.
4.2.8 Choroid and retinal pigment epithelium
The choroid lies between the retina and sclera; it has the functions of providing an absorbing layer for
light passing through the retina and providing nutrients and oxygen to and removing carbon dioxide
from the outer layers of the retina by being a highly vascular tissue. The outermost layer of the retina,
the retinal pigment epithelium provides the major function of metabolising the waste products from
the photosensitive tips of the rods and cones; it also acts as an intermediary, transporting nutrients,
etc. between the choroid and outer layers of the retina. If there is a retinal detachment, which can
occur following a blow to the eye, the retinal pigment epithelium stays attached to the choroid with the
neural layers separating.
4.3 The eye's defence system
The natural defence mechanisms help limit the eyes' exposure to some hazards. The eyelids, eyelashes
and blink reflex provide a mechanical barrier. The blink reflex, particularly in response to a bright flash
of light, will quickly reduce the amount of radiation entering the eye. The constriction of the pupil in
response to the bright light will reduce the amount of radiation entering the eye in the longer term. The
bony cavity containing the eyeball itself, as well as the brow and forehead, provide further protection as
they protrude beyond the eye, particularly in children. The combination of lipids and oils in the tears, as
well as the conjunctiva, provide a further barrier to injury. Natural mechanisms alone are insufficient,
however, to prevent many injuries.
Table 1 gives an over-view of hazards to the various parts of the eye.
ISO 19734:2021(E)
6 © ISO 2021 – All rights reserved
Table 1 — Some causes and consequences of damage to the eye
Mechanical Chemical Optical radiation Biological
Structure of Small Medium Large or fast Acids Alkalis Other UV Visible IR
the eye
Cornea Irritation. Laceration. Rupture. Opacification Opacification. Irritation, Short term None Pain. Infection
Scarring. Loss of con- lacrimation Snow
Epithelial Keratitis Very damag- Opacification
tents blindness.
damage. Longer term ing, from IR lasers
Welder’s
damage Total loss of
flash, arc-eye,
Repairable rapid pene-
sight
photokera-
tration
titis
Long term.
Pterygium
Iris Laceration. IR radiation
incident on
Prolapse through corneal
the iris will
laceration.
increase the
temperature
Detachment at the circum-
of the lens
ference (iridodialysis)
Crystalline Traumatic cataract, Dis- Long term High ambient
lens placement of lens UV Radia- tempera-
tion causing tures (e.g.
photo-degra- above 38 °C)
dation of the may accel-
lens struc- erate aging
ture causing of the lens
cataract (cataract)
Vitreous Intra-ocular foreign body.
Siderosis (rusting)
Retina Haemorrhages. Optic neuritis Lasers
Commotio retina. Photochemical damage,
thermal damage,
Detachment
photoacoustic damage (pulse lasers)
Adnexa Laceration Orbital fracture. Chemical burns. Thermal burns
(skin, eye- and contu-
Damage to lacrimal sys- Permanent scarring
lids, lacrimal sion
tem, Epiphora (overflow-
system, or-
ing tears)
bital bones)
ISO 19734:2021(E)
4.4 Colour perception
The level of colour perception required to carry out work-related tasks will vary. Some tasks will only
require the worker to detect the presence/absence of a coloured object, and so colour recognition is
not important. Nevertheless, a coloured filter could make simple detection difficult because of the
reduction in brightness contrast. Other tasks require the worker to recognize and identify the colour of
objects. Examples could include identification of coloured wires, pipes, signal lights, or gas cylinders. In
other tasks, the worker must be able to discriminate and identify accurately relatively small differences
in colour, such as interpreting pH indicators, diagnostic strips, and the colour of different fuels.
Filters impair colour perception by selective absorption of wavelengths within the visible spectrum
(i.e., coloured filters), lowering the light levels entering the eye to values equivalent to night-time
levels (i.e., grey welding filters), or both (coloured welding filters). However, the filters also help with
colour discrimination in limited and specific circumstances. Cobalt blue filters help in identifying the
temperature of molten metal by reducing the intensity of the light to below levels at which the visual
system’s discrimination ability saturates. Viewing the molten metal through the cobalt blue filter also
accentuates the shift in its colour as the temperature of the metal changes.
Determining the effects of a filter on colour vision can be challenging because the effects are dependent
on the filter's spectral transmittance characteristics, the spectral emittance of the signal light or light
illuminating the object of regard, and the spectral reflective properties of the object(s).
Generally, filters that meet international guidelines for identifying traffic signal light colours would be
appropriate to use when signal lights are used, since they are similar to traffic signals, or the coloured
objects are similar in colour to roadway signage (red, blue, brown, green).
If colour detection and identification of signal lights similar to traffic signal lights is important, then the
values of the relative visual attenuation coefficients (quotients) for traffic signal detection, Q , Q ,
red yellow
Q and Q should be met. All sunglare eye protectors for driving, marked GL0 to GL3, comply with
green blue
a limit on these values as do UV filters marked “UL”, IR filters marked “IL” and welding filters marked
"WL" so these are indicated when colour detection of signals is an issue. However, these filters may not
be suitable for other transportation modes such as the railways because the signal lights are different,
and the viewing distances are longer.
If the task requires discrimination or identification of small differences in colour, then grey filters are
recommended. The luminous transmittance should be greater than 10 % unless the average lighting in
the area is very bright (equivalent to mid-day clear sky or brighter).
About 8 % of the male and 0,5 % of the female population suffer from colour vision deficiencies. These
individuals vary from being so little affected that they may never know and there may be no practical
or occupational consequences to being unable to distinguish colours along the red-green colour axis.
However, very few indeed are truly “colour-blind” as they can distinguish blueness and yellowness
entirely normally. The issues of occupational consequences for these people are not a subject here
except that they may be more affected by tinted lenses and filters than people with normal colour
vision, so extra care may need to be exercised.
The first step in a risk assessment is to assess the need for colour detection and/or recognition in
the workplace. Is there a need to detect or recognise colour accurately and quickly? What are the
consequences of error, trivial though to dire? What is the likelihood of error, common through to rare?
One indication would be if the medical standards already exclude some or all of the people with colour
vision deficiencies.
There are then some engineering solutions that might be applied to reduce the risks. As well as colour
coded, the signals, for instance, could be shape coded, they might vary in size, danger or warning signals
could be larger, they could vary in number (two lights means danger or warning), the important light
could flash and/or could be accompanied by an audible warning (bell or siren).
A short practical experiment may help to identify when the colour of the filter might be an issue.
a) Collect pieces of material/equipment (e.g. cables with the same cable colour coding that is used at
the workplace).
ISO 19734:2021(E)
b) Make sure that the person is in a safe area with illumination (type and intensity) consistent with
their workplace.
c) Clean the eye protector and inspect it for damage (replace the eye protector if necessary, according
to the user instructions).
d) Put the eye protector on according to user instructions.
e) Quickly sort the samples (e.g. cable pieces) by colour.
f) Assess the person's capacity to undertake the job is consistent with the requirements of the role.
g) Carry out a risk assessment of the specific factors in implementing the best solution. See also
[27]
CIE S 017 .
Control strategies where good colour detection and recognition appear important include to ensure that
[28]
— the colours used comply with the appropriate standards. See, for example
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