Artificial Optical Radiation (AOR): Risk Assessment and Worker Protection

Welding without a screen, looking into a melting furnace, working beside a marking laser: three very different situations governed by the same rules. Artificial optical radiation (AOR) is a rarely discussed hazard, often dismissed with a single line in the risk assessment, yet it has dedicated legislation and a precise assessment method.

What artificial optical radiation is

Under Article 214 of Italy's Legislative Decree 81/2008 (D.Lgs. 81/08), optical radiation means all electromagnetic radiation with a wavelength between 100 nm and 1 mm, divided into:

• ultraviolet radiation, 100 to 400 nm, comprising UVA (315-400 nm), UVB (280-315 nm) and UVC (100-280 nm);
• visible radiation, 380 to 780 nm;
• infrared radiation, 780 nm to 1 mm, comprising IRA (780-1400 nm), IRB (1400-3000 nm) and IRC (3000 nm-1 mm).

"Artificial" means produced by man-made sources; solar radiation follows a different assessment logic.

Coherent and incoherent: why the distinction matters

The same article defines laser radiation as optical radiation produced by a laser, and non-coherent radiation as any optical radiation other than laser radiation. The distinction is not academic: it changes the assessment method, the applicable technical standards and which part of Annex XXXVII applies — Part I covers incoherent sources, Part II covers laser radiation.

Where the hazard is found

The most common workplace sources:

• arc welding and plasma cutting (intense UV, blue light, IR);
• melting furnaces, casting, glassmaking and hot work (IR);
• UV-C germicidal lamps for room and surface disinfection;
• UV curing in printing, coating and dentistry;
• industrial lasers for cutting, welding and marking;
• lasers and intense pulsed light (IPL) in medical and aesthetic settings;
• phototherapy and diagnostic lamps in healthcare.

Effects concern mainly the eyes and skin: UV photokeratitis and conjunctivitis, blue-light retinal damage, cataract from IR and UV, erythema and skin ageing, and immediate thermal injury at high exposures.

The legal framework

The European reference is Directive 2006/25/EC on the minimum health and safety requirements regarding the exposure of workers to risks arising from artificial optical radiation. In Italy it is transposed in Legislative Decree 81/2008, Title VIII, Chapter V:

• Art. 213 scope;
• Art. 214 definitions;
• Art. 215 exposure limit values;
• Art. 216 identification of exposure and risk assessment;
• Art. 217 measures to eliminate or reduce risks;
• Art. 218 health surveillance.

Articles 219 and 220 in Chapter VI set penalties for the employer and manager and for the occupational physician respectively. The general provisions on physical agents in Chapter I (Articles 180-186) also apply, including Article 181 on risk assessment and Article 183 on particularly sensitive workers.

Exposure limit values are set out in Annex XXXVII, Part I for incoherent radiation and Part II for laser radiation. They are based on established health effects and biological considerations, and derive from the guidelines of ICNIRP, the International Commission on Non-Ionizing Radiation Protection, adopted in Europe as the basis for legally binding workplace limits.

Risk assessment (Article 216)

Article 216 requires the employer to assess and, where necessary, measure or calculate the levels of optical radiation to which workers may be exposed, as part of the risk assessment under Article 181. An instrumental measurement is therefore not mandatory in every case: many situations can be resolved with manufacturer data and recognised calculations or databases.

The methodology

The law explicitly identifies the technical references to follow:

• the standards of the International Electrotechnical Commission (IEC) for laser radiation;
• the recommendations of the International Commission on Illumination (CIE) and of the European Committee for Standardization (CEN) for incoherent radiation;
• failing that, good practices identified by the Italian permanent advisory commission or, subordinately, scientifically sound national or international guidelines;
• in all cases, data supplied by equipment manufacturers where product directives apply.

What must be considered

Paragraph 2 lists the elements requiring particular attention. Among the most frequently overlooked:

• interaction between optical radiation and photosensitising chemical substances present in the workplace;
• indirect effects: temporary blinding, fire, explosion;
• the presence of multiple sources;
• workers belonging to particularly sensitive groups;
• the availability of alternative equipment with lower emissions;
• laser classification in accordance with the relevant IEC standard and, for artificial sources capable of causing damage similar to a class 3B or 4 laser, analogous classifications.

Paragraph 3 is unambiguous: in the risk assessment document the employer must specify the measures adopted under Articles 217 and 218. Declaring the risk negligible is not enough; it must be justified, and where it is not negligible the measures must be documented. AOR assessment is therefore an integral part of the company risk assessment document and must be updated whenever sources or layout change.

Classifying lasers: EN 60825-1

For coherent sources the established reference is EN 60825-1 (Safety of laser products — Part 1: Equipment classification and requirements), applicable to laser emissions in the 180 nm to 1 mm range. The standard defines classes 1, 1M, 2, 2M, 3R, 3B and 4, with increasing requirements for protection, warning and access control.

In practice the manufacturer's declared class is where assessment starts, not where it ends: actual use must match the conditions of classification. A class 1 product may enclose a class 4 laser that becomes accessible during maintenance, alignment or calibration. Those are the phases where most incidents occur.

Protective measures (Article 217)

The hierarchy is the one common to all physical agents:

1. replace or modify the source, choosing equipment with lower emissions for the same result;
2. shield and enclose: welding booths, curtains opaque at the relevant wavelengths, housings, interlocks on access points;
3. organise the work: limit exposure times, demarcate areas, reduce the number of exposed people, adopt specific procedures for maintenance and alignment;
4. provide signage: areas with hazardous sources must be identified in line with the rules on safety signage in the workplace;
5. protect individually: eyewear and visors with filters matched to the specific wavelength and required optical density, plus clothing covering the skin.

A practical warning on point 5: a filter effective against welding UV offers no protection against a 1064 nm laser. Filter selection depends on the source, not on subjective discomfort — one of the cases where training in the correct use of PPE makes a measurable difference.

Health surveillance (Article 218)

Health surveillance is carried out periodically, normally once a year or at shorter intervals decided by the occupational physician, with particular attention to workers especially sensitive to the risk. The aim is twofold: to prevent and promptly detect adverse health effects, and to prevent long-term effects and the risk of chronic disease arising from exposure. As with carcinogens and mutagens, the latency of some effects — cataract in particular — makes continuity of health data more important than any single check.

Three mistakes to avoid

• Declaring the risk negligible without justification. Article 216(3) requires the risk assessment document to specify the measures adopted: the absence of risk must be argued, not assumed.
• Stopping at the declared class. Real operating conditions, maintenance and multiple sources can change the picture.
• Ignoring photosensitisers. Some medicines and workplace substances lower the damage threshold: the law expressly requires this to be considered.