Occupational exposure to artificial sources of UVR and prevention
Maila Hietanen, Finnish Institute of Occupational Health, Finland
- 1 Introduction
- 2 Occupational exposure to UVR in various applications
- 2.1 Arc welding
- 2.2 Exposure to UVR in various processes
- 2.3 Floodlighting in studios and entertainment facilities
- 2.4 Medical and cosmetic applications
- 2.5 Electronic insect traps
- 2.6 Indoor and outdoor lighting
- 3 Legislation and policies related to occupational exposure to UVR in the EU
- 4 Engineering and administrative control measures
- 4.1 Principles of protective measures for artificial sources of UVR
- 4.2 Engineering control measures
- 4.3 Administrative control measures
- 4.4 Personal protection measures
- 5 References
- 6 Links for further reading
There are more than 1.2 million workers estimated to be exposed to artificial UVR in EU-27 States. Male workers are much often exposed than women, in fact they account for about 90% of all workers exposed to artificial UVR .
On 5 April 2006, the European Parliament and the Council adopted the Directive 2006/25/EC on the minimum health and safety requirements regarding the exposure of workers to risks arising from artificial optical radiation, which defines the exposure limit values (ELVs) on exposure to UVR and other optical radiation . The ELVs are based on established health effects and biological considerations, and hence compliance with these limits ensures that workers exposed to artificial sources of UVR are protected against all adverse health effects.
Occupational exposure to UVR in various applications
Artificial sources of ultraviolet radiation (UVR) are used in many applications in the working environment. While Occupational exposure to natural UVR and prevention has a continuous spectrum from 290 nm to 400 nm at the ground level, sources of artificial UVR emit specific wavelengths depending on the application definitions Accordingly, workers in certain occupations are exposed to significant levels of artificial UVR. These include welders, staff in television studios and on theatre stages, scientific and medical workers, and workers in the graphics industry. Estimated number of workers exposed to artificial UVR in EU countries is about 1.2 million, what constitutes about 1% of total employment in EU .
Welding processes are divided in two broad categories: gas welding and electric arc welding. Mainly arc welding produces hazardous levels of UVR, the quality and quantity of which depend primarily on the arc current, shielding gas and the metals being welded. For example, aluminum welding produces much more UVR than the arc welding of steel using the same arc current . At European worksites, welders are the largest occupational group exposed to hazardous artificial sources of UVR. Generally UVR irradiance levels from welding arcs are very high, and the permissible exposure duration before exceeding the ELVs is typically less than one minute. Studies of worker exposure from welding arcs have shown that the UVR exposure of welders can exceed daily occupational exposure limits to the unprotected eye and skin by several thousand-fold , . Also, a survey of electric arc welders in Denmark showed that 65% of those questioned had experienced erythema, although the frequency of incidences was not reported .
Exposure to UVR in various processes
Sterilization and disinfection
UV radiation is broadly used for the disinfection and sterilization of substances and room air, for example in the food industry to disinfect containers, tools, and work areas. Since UVC in the wavelength range of 250-265 nm is the most effective for inactivating viruses and bacteria, low-pressure mercury discharge lamps are the most commonly used for these purposes. More than 90% of the radiated energy of the lamps is emitted at a wavelength of 254 nm, and the sources are therefore referred to as germicidal lamps, bactericidal lamps, or UVC lamps .
The combination of UVC radiation and ozone is effective in reducing the organic content of water, for instance in swimming pools. In addition, UVC lamps have also been used to decrease the levels of airborne bacteria in operating theatres during surgery, but the technique is not currently widely used, because of the necessity to protect the eyes and skin of personnel and patient.
Exposure at short distances to bare UVC lamps exceeds the exposure limit for the eye and the skin in only a few seconds. In some applications, lamps are used during the night when nobody occupies the room, and motion detectors switch off the lamp if somebody enters the room. A technically simple solution is to house germicidal lamps behind metal barriers, normal glass or plastic which provides adequate protection to workers .
Photocuring and hardening
UVR is used in many industrial processes for photochemical hardening (“drying”), such as the photocuring of lacquers, inks, and glues. Hardening of glues and plastics is often performed with UVA sources, where the exposure is relatively low. However, for special applications, sources that also emit UVB and UVC radiation are used. These processes often use high-power (several kilowatts) lamps. These sources can emit very high levels of UVR, and therefore the industrial process is generally housed in interlocked assemblies and behind opaque baffles to prevent hazardous exposure to personnel during normal work. Nevertheless, UVR can escape via small slits at openings and thus expose the worker.
UV lasers and light emitting diodes (LEDs) are also used in electronic and in printing industry. Modern equipment is normally designed to completely enclose UV sources, however, during maintenance and service potentially hazardous UV exposures can occur 
Checking of banknotes and vouchers
Fluorescent features of banknotes are commonly checked with UVR by cashiers in shops and stores. Also, signature verification can be performed by exposing a signature, written with invisible ink, to a UVA lamp, which fluoresces the signature visible. In general, the electrical power of the UV lamps is low and exposure duration short. In addition, most often the lamps are shielded from direct line of sight, so that normally no occupational UVR hazard to the eyes or the skin results 
UV radiation is used in materials inspection by inducing fluorescence. When fluorescent liquid is applied, it remains in cracks of metal pieces which become visible during irradiation with UVA radiation.
In a fluorescent lamp, light is produced by conversion of the 254 nm to longer wavelength UV radiation by means of a phosphor coating on the inside of the glass envelope of the lamp. Lamps are available with many different phosphors and envelopes to produce a wide range of spectral emissions covering the visible radiation, as well as UVA and UVB regions .
High power sources for metal crack inspection can exceed the exposure limits of the skin and the eyes at typical workplaces. In such cases, the hands should be protected by wearing of gloves, and the eyes can be protected by shielding against a direct line of sight to the lamp (e.g. by mounting the lamp below eye level).
Other applications where UVA induces fluorescence are inspection tasks of fabrics. UVR emissions of low power UV radiation lamps are usually below the exposure limits for typical exposure distances and durations.
Laboratory scientists and other staff engaged in photobiology, photochemistry or laser materials processing use various UVR sources. In these applications, high power UVR lamps and lasers used in various research laboratories may cause occupational health risks to the skin and the eyes of the research personnel 
Floodlighting in studios and entertainment facilities
High power tungsten halogen and metal halide lamps are used for spotlighting in television studios, and on theatre stages. In some working situations, such as typical for news readers and reporters, staff can be exposed to levels of UVR exceeding exposure limits for the eyes and skin. Since it is not possible to use personal protective equipment, the lamps need to be equipped with UV absorbing filters. Also, maintenance personnel working in the vicinity of the lamps can be exposed to high UVR, and they may have to use personal protective equipment .
UVA "blacklight" lamps are frequently used in discotheques, theatres, bars and other entertainment facilities to induce visible fluorescence in clothing and other fluorescent materials. Normally UV radiation levels are well below the exposure limit values. However, sometimes UVC lamps are installed inadvertently instead of UVA lamps, which can lead to severe risks of the eyes and skin .
Medical and cosmetic applications
Diagnostic and phototherapy
Laser devices operating in the UVR spectral region are used in medical environments for diagnostic and treatment procedures. For example, the argon fluoride laser operating at 193 nm is commonly used for corneal refractive surgery procedures 
UV radiation is also widely used in dermatological treatment facilities. The spectral emission of xenon lamps closely matches that of solar radiation. This enables their use as solar radiation simulators, for example in investigating patients with skin diseases induced by solar radiation. Large amounts of UVA, UVB and UVC radiation are emitted by unfiltered xenon lamps, so that they can present a significant health hazard if incorrectly used.
Generally, the output levels of high power UVR lamps are checked with handheld power meters by nurses or doctors inside patient treatment cabinets, and it is important to protect the eyes and the skin during the measurements.
Sunlamps and solaria
Currently, UV sunlamps (solaria) are popular for cosmetic tanning. If the sunbeds in solarium salons are located in specific cabins or behind curtains, UVR transmission through curtains and reflections from ceilings are usually below occupational exposure limits (ELVs) in the vicinity of the cabins . However, surprisingly significant occupational exposure to UVR from solaria may occur in shops where sunbeds are purchased for home use. Typically, shops have tens of UV tanning appliances, sometimes all UV lamps switched on, and hence exposing staff to high levels of UV radiation.
Electronic insect traps
Since UVA radiation (particularly around 350 nm) attracts many flying insects, UVA insect traps are used as electronic fly killers. The lamp is typically mounted behind a high-voltage grid, and insects attracted by the UVA lamps fly into the unit and are electrocuted in the air gap between the high-voltage grid and a grounded metal screen. These units are commonly used in areas where food is prepared and sold to the public. In general, both occupational and public UVR exposure is very low and poses no hazard. However, in some cases UVC lamps have accidentally been used instead of UVA, resulting in severe health problems of the skin and the eyes of exposed staff working close to the traps .
Indoor and outdoor lighting
Quartz halogen or tungsten halogen lamps are widely used in special illumination applications, for instance for specialized task lighting demanding high localized illumination and in clinical instruments. Halogen lamps are filled with inert gas and a small amount of a halogen, such as iodine. Halogen lamps operate at a higher temperature than regular incandescent lamps and emit a broad spectrum of light, which includes UV radiation. Halogen lamp bulbs are often made of quartz because it is more resistant to intense heat. The quartz envelope does not block UV radiation that may present a hazard in some circumstances .
High intensity discharge (HID) mercury lamps are used for roadway lighting, and for lighting of construction sites. UV radiation is usually absorbed by the outer envelope of the lamp, but if the envelope is broken, the internal UV discharge lamp may continue to operate and severe exposure of the eye and skin can occur. Normally roadway lamps are enclosed in impact resistant polycarbonate covers which absorb any hazardous short-wavelength UV radiation. Maintenance workers, who replace lamps and lamp envelopes in areas such as sporting halls and large industrial buildings, need be trained to safe replacement of damaged UV lamps .
Table 2 summarizes exposure conditions using various types of artificial UV radiation sources . The table is intended as guidance only, because the actual overexposure for a given source strongly depends on working distance and exposure duration.
Source: Adopted by author 
On 5th April 2006, the European Parliament and Council adopted Directive 2006/25/EC  on the minimum requirements to protect workers’ safety and health from artificial optical radiation, which includes artificial UVR. The Directive lays down minimum requirements to protect workers from the risks associated with optical radiation, in particular damage to the eyes and to the skin. The Directive establishes exposure limit values (ELVs) based on established health effects and biological considerations. With regard to artificial UVR, the ELVs concern non-coherent UVR as well as coherent UVR, i.e. from laser. The Member States had to transform Directive 2006/25/EC into national law by 27 April 2010.
The Directive also requires the employer to assess and to measure (and/or calculate) the levels of exposure to artificial UVR and to assess the risks to workers, in particular taking into account:
- the level, wavelength range, duration of exposure to artificial sources of optical radiation and the exposure limit values set out in the Annexes to the Directive;
- special circumstances such as multiple sources, indirect effects (blinding, explosion, fire), particularly sensitive risk groups of workers and possible effects resulting from workplace interactions between optical radiation and photosensitising chemical substances;
- standards of the International Electrotechnical Commission (IEC) in respect of laser radiation respectively recommendations of the International Commission on Illumination (CIE) and the European Committee for Standardisation (CEN) in respect of non-coherent radiation;
- principles of prevention set out in the framework directive 89/391/EEC.
Risk assessment shall be recorded on a suitable medium. It shall be furthermore carried out periodically and be updated, particularly if significant changes in working conditions can be observed or if it is indicated by health surveillance results.
The employer has to eliminate or reduce the risks to workers to a minimum following the hierarchy or prevention measures set out in the framework directive 89/391/EEC. If the results of the risk assessment indicate that exposure limit values may be exceeded, the employer shall devise and implement an action plan comprising technical and organisational measures in order to prevent the exposure exceeding the limit values.
The employer shall ensure that workers who are exposed to risks from artificial UVR and their representatives receive all necessary health and safety information and training.
The Member States shall adopt provisions to ensure appropriate health surveillance of workers in order to prevent and to detect timely any adverse health effects, long term health risks and any risk of chronic diseases resulting from the exposure to artificial UVR.
EU Exposure Limit Values (ELVs)
Exposure Limit Values (ELVs) are established for artificial UVR sources only in Directive 2006/25/EC. They are different for non-coherent UVR and coherent UVR (laser).
The ELVs for non-coherent exposure set up in Directive 2006/25/EC are based on the guidelines by the International Commission on Non-Ionising Radiation Protection (ICNIRP). The limits set up in the ICNIRP guidelines “represent conditions under which it is expected that nearly all individuals may be repeatedly exposed without acute adverse effects” and “without noticeable risk of delayed effects”. The guidelines add that, if “a single set of limits can apply for exposure of the eye, it is not possible to provide a single exposure limit that applies to all skin phototypes” and that the ELVs “were developed by considering lightly pigmented populations (i.e. white Caucasian) with greatest sensitivity and genetic predisposition for skin cancer”. However, “highly photosensitive individuals […] may react adversely to exposure at these levels”, and so may do individuals who are “concomitantly exposed to photosensitising agents”. With regard to the field of application of these ELVs, ICNIRP guidelines explain that that they “may be used to evaluate potentially hazardous exposure from UVR; e.g., from arcs, gas and vapor discharges, fluorescent lamps, incandescent sources, and solar radiation”, although “it must be recognized that this limit is difficult to achieve in sunlight and judgment must be used in its practical application”.
To protect workers from hazardous influence of UVR, two ELVs were issued:
- Heff = 30 J*m-2. The spectral irradiance E&and(&and) between 100 nm and 400 nm is weighted by multiplying with S(&and), the spectral weighting taking into account the wavelength dependence of the health effects of UVR on eye and skin (can be found in Table 1.2 of Annex I of the directive). Thus, integration of the weighted spectral irradiance leads to Eeff, the effective irradiance. Taking the exposure time t, Heff is the product of Eeff and t. This ELV is designed for protection of skin and eye and has to be kept within an 8 hour working day. Example: The ELV is reached within 8 hours with a constant irradiation of 1 mW/m².
- HUVA = 10000 J*m-2. The irradiance EUVA between 315 nm and 400 nm is measured without spectral weighting. Taking the exposure time t, HUVA is the product of EUVA and t. This ELV is designed solely for protection of the eyes and has to be kept within an 8 hour working day. Example: The ELV is reached within 8 hours with a constant irradiation of 347 mW/m².
In this article, only applications with UVR are of particular interest. The use of UVR is much more wide-spread with sources of incoherent radiation than with laser sources. Laser sources are shielded more and their use is more restricted and monitored. Thus, the risk of suffering acute or long-term harm can be higher at sources of incoherent radiation The EU Member States had to transpose the EU Directive 2006/25/EC into national law by 27 April 2010. While Directive 2006/25/EC establishes minimum requirements, the EU Member States may decide to establish stricter provisions. Of the 22 EU countries (Austria, Belgium, Cyprus, Czech Republic, Denmark, Finland, France, Germany, Hungary, Iceland, Ireland, Italy, Norway, Lithuania, Luxembourg, The Netherlands, Poland, Spain, Portugal, Slovak Republic, Sweden, UK) that replied to the questionnaire developed in the frame of this project in 2006, Germany and the UK had implemented stricter requirements that Directive 2006/25/EC. Additional UVR limit value on a yearly time basis and specifications for varying and intermittent UVR are required in Germany, while in the UK, the legislation also covers self-employed workers.
Risk assessment with respect to the directive 2006/25/EC, in particular, the risk assessment should include (Article 4 of the directive):
- The level, wavelength range and duration of exposure to artificial sources of optical radiation;
- The exposure limit values;
- Any effects concerning the health and safety of workers belonging to particularly sensitive risk groups;
- Any possible effects on workers’ health and safety resulting from workplace interactions between optical radiation and photosensitising chemical substances;
- Any indirect effects such as temporary blinding, explosion or fire;
- The existence of replacement equipment designed to reduce the levels of exposure to artificial optical radiation;
- Appropriate information obtained from health surveillance, including published information, as far as possible;
- Multiple sources of exposure to artificial optical radiation;
- A classification applied to a laser as defined in accordance with the relevant IEC standard and, in relation to any artificial source likely to cause damage similar to that of a laser of class 3B or 4, any similar classification;
- Information provided by the manufacturers of optical radiation sources and associated work equipment in accordance with the relevant Community Directives.
Aim of risk assessment is to state if worker’s exposure to UVR can lead to adverse effects on human health or not.
Because of diversity of possible health effects, their temporal, spatial and spectral dependence, the range of individual sensitivities to these effects and variety of possible exposures risk assessment methods related to UVR radiation varies for natural and artificial sources. For artificial sources the risk assessment is mostly based on daily UVR exposure of workers in comparison with exposure limit values. For solar radiation which is not controllable at source and changes in time the methods based on quantitative exposure limits (like for artificial sources) are not applicable.
Engineering and administrative control measures
If the risk assessment has been conducted, and the compliance with the limit values is not ensured, protective measures have to be chosen. Additionally, persons belonging to a special risk group (e. g. photosensitised persons) should be supplied with personal protective equipment. The collectivity of the protective measures has to ensure that the ELVs are kept.
In some cases the UV source is contained within an enclosure with no risk of exposure to personnel. In other applications workers can be exposed to UVR either directly from the UVR source or by reflection or scattering from adjacent surfaces. In these situations, various engineering and administrative control measures and are needed. Uncontrolled UVR emissions should be avoided in the workplace.
Principles of protective measures for artificial sources of UVR
To reduce exposure, a sequence of protective measures can be introduced:
- Avoiding or minimisation by choosing of alternative working procedure:
- Special cases, other procedures without UVR can be applied, e. g. adhesive bonding instead of welding, application of cameras instead of direct observation of a process;
- Technical measures:
- Primarily at the source: capping, shielding, blinding, optical filters;
- Organizational measures:
- Here, measures regarding room and time-management are subsumed, e. g. increasing the distance between source and worker, or optimised time scheduling for the workplace;
- Personal protective equipment (skin and eyes).
If protective measures applied so far are not sufficient, have to be taken into account. Certain harmonized European norms give support in choosing the correct protection.
Engineering control measures
Use of enclosures and screens
The main engineering control measures are use of light-tight cabinets and enclosures, UVR absorbing glass and plastic baffles. Sealed enclosures can have observation ports, made of UVR absorbent material such as acrylic, PVC and window glass. When access close to the source is required, for example during maintenance or repair work, fail-safe interlocks should be used .
Shields, curtains and baffles can be used to protect bystander workers from UVR emitted by open arc processes such as arc welding, arc cutting and plasma spraying. However, in such processes administrative controls and personal protective equipment are also important 1 .
Elimination of reflected UVR
Many surfaces, especially those that are visibly shiny, are often good reflectors of UVR. To reduce the intensity of reflected UV radiation, surfaces can be coated or painted with appropriate non-UVR reflective material. Organic UV absorbers are capable of blocking almost 100% of UV radiation between 300 nm to 380 nm, but they also increase the absorption of visible light that should be taken into account at work tasks which require good lighting conditions.
Administrative control measures
People working with a UVR source or maintaining such a source should receive adequate OSH training to understand the need for control of the hazards involved and to carry out their work safely. Information and training of workers on the risks of exposure to UVR and related health effects have been found as insufficient. Most often, over-exposure of indoor workers arise from failures to apply administrative safety measures or eye and skin protective equipment.
Especially necessary is to improve protection measures of specific highly exposed groups of workers. It concerns particularly welders, who suffer complaints and diseases of eyes mostly due to erroneous choosing and using of personal protective equipment .
Limitation of access
Access to work area where hazardous levels of UVR exist should be restricted to those informed of the potential hazards and trained in appropriate protective measures. Effective control measures include keeping the exposure duration to a minimum and increasing the distance of a worker as far away from the source as is practicable.
Hazard warnings and signs
Hazard warning signs should be used to indicate the presence of a potential UV radiation hazard when exposure is likely to exceed recommended exposure limits. The warning signs can also indicate restriction of access, and the need for personal protection equipment. Warning signs and lights may also be used to show when the equipment, such as a laser device, is energized .
Personal protection measures
Protection of the skin
During occupational exposure to artificial UV radiation sources, the areas of the skin most usually at risk are the backs of the hands, the face, the head and the neck, as other areas are generally covered by working clothes.
The protection of the skin must ensure the reduction of the exposition below the ELVs. The following measures can be helpful:
- Shields visor and cap to ensure protection of the skin in the face. It is important that the helmet will protect both the head and the neck against UV radiation .
- Gloves - hands can effectively be protected by wearing gloves with low UVR transmission;
- Tight shoes and gaiters;
- Leather cap for the neck;
- Long-sleeved clothing;
- Security windows with filter effect.
Protection of the eyes
The eye protection against UVR is necessary to avoid short-term, as well as long-term ailments. Goggles, spectacles, visors or face shields, which absorb UV radiation, should be worn where there is a potential eye hazard. The highest levels of UVR commonly existing at indoor work occur during electric arc welding, which produces high levels of all wavelengths of UV radiation, including high irradiance in the UVC region. In addition to UVR, there is also risk of retinal damage from the intense visible radiation emitted. Welders should be protected by a welding helmet or a mask fitted with absorption filters meeting appropriate European Norms .
Even in the non-welding areas of factories where welding equipment is used, ambient UV radiation levels can exceed occupational exposure limit values during a working day. Therefore, not only the welder needs to be protected but also helpers should wear personal protective equipment. Protection against UVR is also important if there are other welding arcs working in the vicinity. Eye hazard (“welders flash”) may occur from adjacent arcs when a face shield is temporarily not in place, for instance while inspecting the weld or manipulating the work-piece. In addition, non-involved staff in the surrounding of the welding workplace should be protected by appropriate shielding of the welding workplace .
- EU-OSHA - European Agency for Safety and Health at Work, Expert forecast on emerging physical risks related to occupational safety and health. Luxemburg, 2005. Available at: 
- EC – European Commission, Directive 2006/25/EC of the European Parliament and of the Council on the minimum health and safety requirements regarding the exposure of workers to risks arising from physical agents (artificial optical radiation) (19th individual Directive within the meaning of Article 16(1) of Directive 89/391/EEC), OJ L 114, pp. 38-58, 2006. Available at: 
- EU-OSHA, Project P-06-07: Emerging risks report on ultraviolet radiation, 2006 (unpublished report)
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- EN – European Norm 1088, 1995 Interlocking devices associated with guards
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Links for further reading
EU-OSHA – European Agency for Safety and Health at Work, Guidance on risk assessment at work, ECSC-EC-EAEC, Luxembourg, 1996, 64 p. Available at: 
ICNIRP - International Commission on Non-Ionizing Radiation Protection, Guidelines on limits of exposure to ultraviolet radiation of wavelengths between 180 nm and 400 nm (incoherent optical radiation), Health Phys, 2004, 87, pp.171–186. Available at: 
IEC - International Electrotechnical Commission, Photobiological safety of lamps and lamp systems, Geneva, IEC, 2006.
EC - European Commission, Non-binding guide to good practice for implementing Directive 2006/25/EC(Artificial optical radiation), Luxembourg, Publications Office of the European Union, 2011, 137 pp. Available at: 
Practical Laser Safety, D.C. Winburn, Marcel Dekker Inc., New York, 1985.
The Use of Lasers in the Workplace: A Practical Guide, International Labour Office, Geneva, 1993.
Turner, J., UV reflections from building materials, Univ Queenlands, 2011. Available at: 
WHO – World health Organization, Ultraviolet radiation as a hazard in the workplace, WHO, 2003. Available at: