In brief
Artificial optical radiation is the ultraviolet, visible and infrared radiation emitted by sources such as welding arcs, plasma cutting, lasers, melting furnaces and UV curing. UV from welding arcs can cause "arc eye", which appears a few hours later, and skin burns; infrared can cause cataracts in the long term; and class 3B and 4 lasers can cause instant eye damage. Protection is provided by booths and welding screens that enclose the source, interlocked enclosures on laser machines and eye protection suited to the wavelength. These sources should be addressed separately in the risk assessment.
What is artificial optical radiation, and where is it found at work?
Optical radiation is electromagnetic radiation emitted at wavelengths between 100 nanometres and 1 millimetre, and is divided into three regions: ultraviolet (UV), visible light and infrared (IR). The sun is a natural source; radiation emitted by any man-made source is called artificial optical radiation. These sources fall into two groups: lasers (coherent) and non-coherent sources such as lamps, arcs, flames and hot surfaces.
Office lighting and computer screens are also sources of artificial optical radiation, but they do not pose a risk in normal use. The sources that really need attention are the following tasks, which are also listed in the Guide to Health and Safety Measures in Work with Artificial Optical Radiation Sources published by the General Directorate of OHS of the Ministry of Labour and Social Security:
- Arc and oxy-gas welding, plasma cutting,
- Laser cutting, welding, marking and drilling,
- Glass and metal melting furnaces, casting and heat treatment,
- UV curing of paints and inks, UV curing in vehicle repair,
- Non-destructive testing and sterilisation with UV lamps.
In metalworking, automotive supplier and foundry businesses in Bursa and the surrounding provinces, most of these sources are found under the same roof. The guide was prepared on the basis of the EU's implementation guide for Directive 2006/25/EC; in its own words, it does not replace legal provisions, but it is a detailed reference for exposure limit values, laser classes and measures.
Effects of artificial optical radiation on the eyes and skin
The harm caused by optical radiation depends on wavelength: UV affects the front surface of the eye and the skin; visible light and near infrared affect the retina; and far infrared affects the cornea and skin thermally. The table in the Ministry's guide can be summarised as follows:
| Region | Wavelength (nm) | In the eye | On the skin |
|---|---|---|---|
| UVC | 100–280 | Photokeratitis and conjunctivitis | Redness, skin cancer |
| UVB | 280–315 | Keratitis, conjunctivitis, cataract | Redness, premature ageing, skin cancer |
| UVA | 315–400 | Keratitis, conjunctivitis, cataract, retinal damage | Redness, premature ageing, skin cancer |
| Visible | 400–700 | Retinal damage (blue light hazard), retinal burn | Burns |
| IR-A | 700–1,400 | Cataract, retinal burn | Burns |
| IR-B | 1,400–3,000 | Cataract | Burns |
| IR-C | 3,000 nm–1 mm | Corneal burn | Burns |
The effects are of two kinds. Acute effects, such as arc eye or skin burns, occur when a certain threshold is exceeded, and exposure limit values aim to keep below these thresholds. Chronic effects, such as cataracts and skin cancer, build up over years; as the guide emphasises, there is generally no threshold below which they will not occur at all. That is why keeping exposure as low as possible is essential.
Welding arc UV: the welder and those nearby
The welding arc is one of the most intense UV sources in industry. In a person who looks at welding arc UV without protection, a gritty feeling in the eye, watering, inability to look at light and severe pain begin a few hours later, often at night. This condition, called "arc eye", is a UV burn of the cornea. The same radiation causes redness similar to sunburn on exposed parts of the neck, face and arms.
In welding, the optical radiation risk affects not only the welder but also those nearby: the operator at the next workstation, the forklift driver moving materials, a visitor passing near the welding area. Reflections of the welding arc also come from light-coloured and shiny surfaces. The measures are:
- Welding curtains and screens: Fixed welding stations are surrounded by curtains. Transparent welding curtains (EN ISO 25980) protect those nearby by reducing UV and blue light; they are not a filter the welder can use to watch the arc.
- Booth surfaces: Booth walls are kept matt and dark to reduce reflection.
- The welder's face protection: The filter number on the welding mask is chosen according to the welding process and current (EN 169); higher current requires a darker filter. With auto-darkening filters (EN 379), the shade range and response time must suit the work being done.
- Skin protection: Long-sleeved, flame-retardant clothing, gloves and neck protection; welding is not done in a short-sleeved T-shirt.
- Helpers: A person holding parts for the welder or grinding uses goggles or a visor with a suitable filter.
For welders' other risks, see our article on welders' occupational safety risks, and for choosing filters and visors, see our article on safety glasses and face shields.
Laser safety in the workplace: classes and enclosed machines
Lasers are divided into classes according to their level of hazard. The first question of laser safety in the workplace is which class the device belongs to. According to the Ministry's guide, the classes are briefly as follows:
| Class | Definition | Example |
|---|---|---|
| 1 | Safe in normal use; may be a high-power laser inside an enclosure that prevents access to the beam | Enclosed material processing lasers, laser printers |
| 1M | Safe for the naked eye; may be hazardous when viewed through binoculars or a magnifier | Some fibre optic communication systems |
| 2 | Visible beam; the blink reflex protects in momentary exposure, deliberate staring is hazardous | Barcode scanners |
| 2M | Like class 2; hazardous when viewed through optical instruments | Alignment and levelling devices |
| 3R | Low but real risk in the direct beam | Alignment lasers, high-power pointers |
| 3B | Direct beam and close reflections can damage the eye | Research and therapy lasers |
| 4 | Direct, reflected and scattered beams hazardous to eyes and skin; fire risk | Laser cutting and welding sources |
Laser cutting machines in factories are mostly presented as class 1 in normal use; however, this means that the class 4 laser source inside is enclosed by an interlocked enclosure. The risk arises when the enclosure is opened, the interlock key is bridged, or service and alignment work is carried out. The Ministry's guide also requires class 3B and 4 laser products not to be used without a risk assessment. Therefore:
- Cover interlock systems are not disabled; maintenance mode is used only by an authorised person and under a written procedure.
- For service work requiring operation with the enclosure open, the area is closed off, warning signs are put up and only trained persons are present.
- Laser protective eyewear is chosen according to the device's wavelength and power (EN 207); there is separate eyewear for alignment work (EN 208). Eyewear suitable for one laser may not provide protection against another laser with a different wavelength.
- Reflections from shiny metal surfaces and the fume and fire risk during cutting are also assessed.
For other risks specific to laser cutting machines, see our article on laser cutting machine safety.
Infrared radiation: furnaces, casting and glass
Melting furnaces, casting ladles, heat treatment furnaces and glass processing emit intense infrared radiation. Infrared radiation can cause cataracts in the eye over many years; at high intensity it burns the cornea and skin. The same sources also increase heat stress.
Measures against infrared radiation:
- Furnace openings and ladles are kept closed as far as possible; heat shields and reflective screens are used.
- Viewing windows with suitable filters are preferred for monitoring inside the furnace.
- Employees at the furnace use goggles or visors with infrared filters (EN 171).
- Exposure time is shortened through work organisation; cooling-off and drinking breaks are planned.
For other risks in foundry work, see our article on occupational safety in foundries, and for hot environments, see our article on industrial heat stress.
Optical radiation in the risk assessment
Art. 10 of Law No. 6331 requires a risk assessment, and Art. 8 of the Risk Assessment Regulation requires physical hazard sources to be identified and, where necessary, checks, measurements and investigations relating to them to be carried out. Optical radiation is one of these physical hazards. In practice, the following order is followed:
- An inventory of sources is drawn up. Welding machines, lasers, furnaces, UV lamps and their locations are listed.
- Trivial sources are set aside. Sources listed in the guide, such as office lighting and screens, do not require a detailed assessment in normal use.
- Exposure is assessed for hazardous sources. Often the laser class, wavelength and power information provided by the manufacturer, and the type of welding process, give a sufficient picture. If measurement or calculation is needed, we plan it with authorised laboratories and healthcare institutions.
- Who is affected is determined. Those at neighbouring workstations, maintenance staff and visitors are on the list as well as the welder.
- Measures are chosen according to the hierarchy of controls, and the risk is scored again after they have been implemented.
- Employees are trained. The guide states that training is always necessary for those working with class 3B and 4 lasers.
In health surveillance, the workplace physician asks about eye and skin complaints at pre-employment and periodic examinations; the record of arc eye cases is valuable data showing which station lacks a curtain or filter. For other risks in the metal and machinery sector, see our metal and machinery page. We prepare the inventory and risk assessment of optical radiation sources as part of our risk assessment service.
Frequently Asked Questions
Why does the burning in the eye from welding start late?
The UV radiation of the welding arc causes a burn on the cornea, and symptoms usually appear a few hours later, often at night. A gritty feeling in the eye, watering and inability to look at light are typical; a doctor should be consulted.
Why is a welding screen necessary?
The UV and blue light of the welding arc affect not only the welder but also nearby employees. Welding curtains and screens limit the spread of this radiation to the surroundings; they do not replace the welder's own mask.
Is an enclosed laser cutting machine safe?
In normal use, a laser inside an interlocked enclosure is safe. The risk arises when cover interlocks are bridged or service and alignment work is done with the enclosure open. This work is done under a written procedure and with suitable laser eyewear.
How is laser eyewear chosen?
Laser protective eyewear is chosen according to the device's wavelength and power; the wavelength range it protects against and the protection level are marked on the eyewear. The same eyewear may not provide protection for a laser with a different wavelength.
A risk assessment that identifies and scores hazards on site, links each measure to an owner and a date, and has a clear renewal schedule.
Bursa SİSTEMER OSGB Technical Team — written from the field experience of our OHS specialists and workplace physicians. Legal information is valid as of the publication/update date; contact us for an assessment specific to your business.