The Eyes and Face
Published: 10th Apr 2005
The human eye is fragile and vulnerable. A lesion to one of its components can mean anything from surface irritation to irreversible after effects such as a total loss of vision.
In the same way, impacts to the face by projectiles or hot or aggressive liquids could lead to irreversible damage and visible scars.
The first consideration for the prevention of the risk of accidents must be the implementation of technical and organisational measures aimed at eliminating the risks at source or at protecting the workers thanks to collective protection. When these measurements prove to be insufficient or impossible to set up, the recourse to PPE is essential to prevent the residual risks.
Risks to which the eyes are exposed
At the workplace, the eyes and face of workers are likely to be exposed to risks of a much diversified nature:
The mechanical risk appears, in the majority of cases, during the operating of machinery where flying sharp-edged particles have significant and sufficient kinetic energy (metal chips, splinters or fragments of tools, water under pressure, etc). The risk also exists in activities creating clouds of dust (abrasive action at eye-level) and in the presence of flying liquid or molten solid particles.
The chemical risk occurs when a substance is projected, or present in the ambient conditions, reacts with the components of the eye or the skin. This risk appears in the majority of the industrial sectors in the form of powders, aerosols, liquids, gas or vapour.
The biological risk is present, especially in the medical environment or in waste management, when micro-organisms could contaminate workers. This risk is also present in the mediums favourable to the development of micro-organisms such as recycled cutting oil vats, air-conditioners, etc.
The risk of optical radiations (IR, visible, UV, lasers) appears in many industrial or commercial activities (welding, steel industry, foundry, glass industry, surgery). An over-exposure of the eye to sources of high intensity can cause burns and irreversible damage.
Thermal risk comes into play with the projection of liquids or hot solids or the emission of intense radiation (furnaces, for example).
The presence of electric arc subjects the eye to several risks: radiations, UV, projection of particles and heat.
The analysis of all of the risks at a work station is an essential and preliminary step in employee protection.
The three types of eye and face protectors
a) Spectacles - Spectacles are eye protectors with oculars mounted in a spectacle-type frame with branches, with or without lateral protection. They could be mounted with twin oculars within a conventional spectacle-type frame or with single-piece ocular, usually with cheek and brow protection for additional protection. Some models can be equipped with corrective lenses. Single eyepiece glasses can be worn over normal corrective spectacles.
b) Goggles - Goggles are eye protectors that tightly enclose the orbital area and sit on the face. They are designed with one eyepiece in a malleable frame or with twin oculars in an opaque cup frame. Goggles are kept in place by an elastic headband which can be adjusted by the user to ensure a good fit.
Goggles can have direct or indirect ventilation which reduces possible mist formation. Corrective glasses can be worn under certain models of single eyepiece goggles but it is impossible under a mask with two eyepieces. Certain models are recommended for protection against chemical risks due to good tight fitting properties.
c) Face-shields - Eye-protectors covering all or most of the face. They may also include devices to protect the wearer’s ear, throat and respiratory tract. They are fixed to a browguard with adjustable headband, or attached via a carrier to a safety helmet or hood. For intermittent use hand held screens exist. They ensure total protection for the eyes and face but not the fit to protect against ambient conditions. The face screens can be worn over corrective glasses.
For welding activities, face-shields are equipped with filters designed to protect against radiation. There are other types of sophisticated welding masks:
- Equipped with electro-optical filter which darkens automatically when the arc of welding is started
- Masks with double scale number with a clear zone for the pointing of the electrode and the arc initiation and a darker zone allowing observation of the welding process
Basic requirements for eye and face protectors
The EN166 standard defines the basic requirements for all eye protection with regard to their minimal resistance and their optical qualities. This standard comprises specifications corresponding to the risks such as mechanical, thermal, chemical and radiation.
a) Resistance to the current hazards - Conformity to the standard EN166 offers a guarantee of minimal resistance to the current risks such as low energy impacts, ageing, exposure to heat and corrosion.
A guarantee of reinforced solidity is obligatory for the eyepieces without filter action and any ocular or complete eye protector. A test involving a 43g 22mm steel ball travelling at 5.1m/s will validate this guarantee. In this case an "S" symbol would be affixed to the eyepiece and/or mounting.
b) Optical qualities - The requirements for optical qualities are aimed at the users comfort and non-impaired vision. Three optical classes are defined in the standard EN166:
- Class 1 is recommended for permanent usage or close-up work
- Class 2 is usable for intermittent usage
- Class 3 is usable only for very short duration
Other requirements for eye and face protectors
Protection against high speed particles - Three additional levels of mechanical resistance are described in standard EN166. They aim at protecting the user against projection from particles in the machining field (sandpapering, grinding, milling, engraving, blasting, etc):
Impact resistance of particle with low energy: the eyepieces must resist the impact of a steel ball 6mm in diameter, of 0.86g, launched at a speed of 45m/s. The symbol of marking will be "F"
Impact resistance of particle with low energy: the test is similar to the previous one, the speed being 120m/s. The symbol of marking will be "B"
Impact resistance of particle with low energy: the test is similar to the first, the speed being of 190m/s. The symbol of marking will be "A"
Protection against molten metals and hot solids - The protection capability of the PPE against molten metal splashes (100g of grey iron at 1450°c and 38g of aluminium at 750°c) and against contact with hot solids (6mm steel ball at 900°C). The symbol of marking is "9".
Protection against optical radiation - A series of European standards treat protection against radiation. They help with the choice of suitable filters according to the nature and of the power of the radiation sources. The transmission characteristics of the filters are indicated by a scale, consisting of a code number for the type of filter UV, IR, etc (except for welding filters) and a shade number (class of protection).
When the filters chosen cause a feeling of discomfort a test of the working conditions and the sight of the operator are essential. The recommendations given in the standards are not applicable to people having photophobia or those who are under medical treatment and who may have an increased sensitivity to optical radiation.
The annx to standard EN169 relating to filters for welding makes it possible to choose the suitable filter from the type of welding process and its characteristics (intensity of current, flow rate of acetylene, etc). In the case of welding filters, it should be noted that the scale number only comprises the shade number.
According to conditions of use it is possible to use a filter of a level immediately higher or lower, but it can be dangerous to use filters even of too high a level (too dark) that could lead the operator to approach the radiation source and breathe the harmful fumes.
b) Ultraviolet radiation
Standard EN 170 helps with the choice of filters against ultraviolet with a code number of 2 or 2 C . The number code 2 informs us that the perception of colours can be faded whereas the filters of number code 2 C do not generate significant modification to colours.
c) Infra-red radiation
For protection against infra-red radiation standard EN 171 recommends that filters must be selected from those with code number 4 or 4 C. Filters that have a reflective face are recommended when the level of radiation is very high because they allow a reduction in the temperature of the filter. The 4 C code indicates that the filter allows a better colour recognition.
d) Solar radiation
Sunglasses aim to protect the eye against excessive solar radiation, reduce eye strain and increase visual perception. Besides the absorption of visible light and the reduction of glare, protection can also be ensured in the ultraviolet and, in some cases, the infrared spectrum. In order to ensure fatigue-free vision for prolonged usage the choice of filter depends on the level of ambient light and on the individual sensitivity to glare. In case of doubt, professional ophthalmic advice should be sought. The recommendations for sunglasses and sunglare filters are given in standard EN172 (industrial use) or EN1836 (general use).
For the direct observation of the sun, sun filters or eye protectors with categories E12 to E16 as specified in EN 1836: 1997/A2 should be used . Welding filters of scale number 12 to 16.are equally suitable.
e) Laser radiation
The selection of an eye protector for laser depends on the type of laser and of the operating conditions. For direct laser protection, eye protectors in accordance with EN 207 must be specified. Their performance relates to the types of lasers (continuous wave laser, pulsed lasers), the wavelength, power and energy of the laser beam.
For laser adjustment work on lasers and laser systems in the visible range, where the path of the beam has to be seen, eye protectors in accordance with EN 208 must be provided. These filters are not suitable for looking directly into the laser beam. They only provide a protection against damage from an accidental direct look at the beam if the eyelid closes within 0,25s (blink reflex) If this reflex is altered (medical treatment, sickness,...) this protection is no longer ensured.
|TYPE OF RISK||TYPE of PROTECTOR to be used||EXAMPLES of FIELD of USE||APPLICABLE EN STANDARDS|
|Current mechanical risks (e.g. impact energy of 22mm steel ball at 5,1 m/s or of 6 mm steel ball at 120 m/s)||All types||General use, metal machinery, wood turning, tree felling...||EN 166|
High mechanical risks
||Weld chipping, cutting, riveting, stone dressing, grinding, sculpturing, rock drilling,||EN 166|
|Liquid splashes||Only face-shields||Water jet blasting, water cleaning, bleaching, battery filling, electrolytic plating, paint stripping, chlorination processing...||EN 166|
|Liquid droplets||Only goggles||Crop spraying,||EN 166|
|Molten metal splashes and contact with hot solids||Only goggles and face shields||Metal pouring, metal skimming, die casting, metal flame cutting, soldering...||EN 166|
|Radiant heat||Only face-shields||Furnace work, metal pouring/smelting, metal casting, gaswelding/brazing, Flame cutting,||EN 166, 1731|
|Short circuit electrical arcs||Only face-shields||Work on electrical power transmission systems||EN 166|
|Gas and Coarse/fine dust particles||Only Goggles||Cement mixing, wall sanding, lime spreading, powder coating, varnishing, adhesive bonding, exhaust gas analysis, fumigation||EN 166|
Other aspects to be considered
Compatibility - Often, eye protection is worn with other types of PPE such as helmet, ear muffs or respiratory protective devices. It is necessary to check the compatibility of this equipment, i.e. to make sure that the wearing of one does not affect the fit of the other (for example glasses with branches obstructing the adjustment of a filter half-mask). Face-shields don’t generally cause incompatibility problems when worn over filtering face-piece respirators.
Consider too the use of equipment offering multiple protection, such as a powered helmet respirator and supplied air visors that combine eye protection with respiratory or other kinds of protection.
Comfort - Elements that result in excellent acceptance include:
- Adjustable side-arms and tilting frame
- Weight and balance of the protector
- Design of the nose-bridge
- A flexible and broad joint on the goggles
- Anti-fogging and abrasion resistant coatings on oculars/lenses
Purchase and putting into service
The call for tender - The conditions established from the evaluation of risks and constraints constitutes the basis of the invitation to tender.
The probation period - Before finalising the choice of eye protection it is essential to plan a probation period of "wear testing" in normal work conditions in order to locate the particular difficulties of the activity, as well as the variations in morphology, or problems of vision for employees. It is also necessary to take into account the aesthetic choices of workers in order to encourage the effective use of the protectors.
The final choice - In order to minimise constrain and discomfort caused by the wearing of eye protectors, it’s a question of finding, in dialogue with the employees, the best compromise between the need for protecting the eyes and/or the face and the requirements of the activity.
The delivery - On delivery of PPE the purchaser must make sure that technical levels match his expectations. A good method is to check the CE marking and standards related to the PPE, and the instructions for use which have to accompany all PPE.
In the instructions for use, one will find very useful information regarding:
- Storage, cleaning, maintenance
- Performance, limits of use, usable accessories
- Significance of markings
If the language in which the instructions are written is not understood by any workers, the employer must acquire all adequate information and present it in a comprehensible way for these workers.
Placing at worker’s disposal - At the time of provision of eye and/or face protectors information for the personnel on their optimal use is essential. The instruction for use must be supplied to the user. If necessary, the employer must arrange adequate training for using the PPE.
The product’s individual adaptability, such as flexible adjustable armed branches, will aid the appropriation of the eye protector by the end-user. The supply of a case will encourage the user to take care of them.
Eye protectors are subjected to much abuse in relation to their storage, use and maintenance. This can be mechanical deterioration (abrasion, scratches, etc) or chemical (inappropriate detergent, solvents). These factors are likely to lessen the level of protection offered. Also, dirty or damaged oculars or visors affect vision; they represent an constrainfor the correct execution of the task; they can cause visual tiredness, and cause the rejection of the equipment by the users. They will be used less and less.
The company will be careful to make available a means of cleaning their protectors according to instructions from the manufacturer. The use of a soft and nonabrasive detergent, of hot water and drying with a soft cloth will ensure correct cleaning.
In addition, eyepieces will have to be checked and replaced as soon as transparency is affected. Look out for:
- a modification of colour of the eyepiece - cracking of abrasion resistant coating - strong abrasion or scratches to the surface - the adherence of molten metal particles
Any damaged equipment will have to be discarded and replaced. Any change of eyepiece or screen will be carried out by a competent person according to the instructions of the manufacturers.
Be careful not to put the eyepiece face-downwards on the bench and try to store in individual cases away from radiation, moisture and high temperatures.
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Published: 10th Apr 2005 in Health and Safety International