Optical radiation and worker protection

Artificial optical radiation (AOR) requires careful and conscious management to ensure the safety and health of workers. The reference point is Legislative Decree 81/08 and subsequent amendments, Title VIII, Chapter V which defines the field of application.

ROA includes all electromagnetic radiation in the wavelength range between 100 nm and 1 mm, including ultraviolet radiation, visible light and infrared radiation.

optical-radiations

ROA includes all electromagnetic radiation in the wavelength range between 100 nm and 1 mm, including ultraviolet radiation, visible light, and infrared radiation. Unlike natural optical radiation, such as sunlight, ROA is produced by artificial sources, often found in industrial, medical, and research processes.

Artificial optical radiation sources

ROA sources are divided into two main categories:

Coherent sources (lasers):

  • laser for industrial processes,
  • lasers for medical applications,
  • laser for measurements and alignments.

Inconsistent sources:

  • lighting lamps,
  • welding equipment,
  • industrial ovens,
  • UV sterilization systems.

ROAs are present in many industrial processes. Welding generates both UV and IR radiation; industrial drying often uses IR radiation for the treatment of paints and coatings. In the food and medical industries, UV sterilization is widely used.

Risk assessment, prevention and protection measures, health surveillance

Assessing the risk from exposure to artificial optical radiation requires a thorough analysis that includes measurements of radiation levels, the work context and the way in which activities are carried out.

First of all, you need to identify radiation sources and the possible presence of reflective surfaces that can increase the actual exposure of workers. Subsequently, it is necessary to consider the operating methods: the distance between the worker and the source, the exposure times and the position assumed during work.

The first line of defense consists in the installation of protective screens and barriers. These devices must be designed considering the type of radiation and the operational needs of the work process. Secondly, we have PPE, the choice of which must be made considering both the type of radiation present and the characteristics of the work to be performed. Protective glasses, for example, must be equipped with specific filters for the wavelengths present and must guarantee adequate comfort for prolonged use.

Since the effects of exposure can occur both immediately and in the long term, the occupational physician must evaluate the suitability of workers to perform tasks that involve exposure to ROA. The health surveillance program must be customized based on exposure levels and individual characteristics of workers. Periodic checks may include ophthalmological and dermatological visits with variable frequency based on the level of risk.

Emergency training and management

Fundamental is the ability of workers and emergency personnel to quickly recognize potentially dangerous situations and know how to behave accordingly. Not only knowing the procedures for turning off machinery and evacuation procedures, but also knowing how to provide specific first aid for the different types of exposure to ROA.

Documenting incidents and near misses is another key aspect of emergency management. Each event must be carefully recorded and analyzed, not so much to identify responsibilities, but to understand the root causes and improve preventive measures. This retrospective analysis allows for continuous refinement of emergency procedures and identification of potential weaknesses in the protection system.

The EN 14255 standard

The EN 14255 standard provides precise methodologies for the assessment of personal exposure. The main objective of EN 14255 is the assessment and measurement of exposure to optical radiation, in particular ultraviolet (UV) radiation, both natural and artificial. The standard is divided into several parts, each with a specific focus.

  • Measurement and assessment of personal exposure to incoherent optical radiation: The focus of EN 14255-1 is on ultraviolet radiation emitted by artificial sources in the workplace. It includes prevention and protection measures for the safe use of UV sources.
  • Visible and infrared radiation emitted by artificial sources at workplaces: this section (EN 14255-2) deals with the measurement and evaluation of visible and infrared radiation emitted by artificial sources.
  • Solar radiation risk assessment: EN 14255-3 describes procedures for measuring or estimating and evaluating solar UV exposures. It is used to assess solar radiation risk exposure to skin and eyes, considering factors such as geographical location, season, time of day, altitude and cloud cover. In addition, the third part of the standard provides assessment methods: models are provided to determine exposure factors and is applicable to specific conditions in terms of location and climate.

In the specific field of laser safety, the IEC 60825 standard is the international reference point. This standard, constantly updated, defines a classification system for lasers based on their level of danger and provides detailed guidelines for their safe installation and use. Particularly important is the part dedicated to the technical requirements of protection systems and the safety procedures to be adopted for the different classes of lasers.

IEC 60825

In the specific field of laser safety, the IEC 60825 standard is the international reference point. This standard, constantly updated, defines a classification system for lasers based on their level of danger and provides detailed guidelines for their safe installation and use. Particularly important is the part dedicated to the technical requirements of protection systems and the safety procedures to be adopted for the different classes of lasers.

Laser classification

The classification according to IEC 60825-1 is based on the danger of lasers and the potential risk to eyes and skin. Here are the classes in increasing order of danger:

Class 1: Lasers that are intrinsically safe and not dangerous under reasonably foreseeable conditions of use. They are characterized by very low power. Examples of this class are DVD players and laser printers.

Class 1M: Like Class 1 lasers, but potentially hazardous when viewed with optical instruments. Use of optical instruments (magnifiers, microscopes) may increase the risk. Example: some telecommunications optical fibres.

Class 2: Low power visible lasers (≤ 1 mW). Eye protection is ensured by the palpebral reflex (0.25s). They are safe for short exposures. Example: barcode scanners.

Class 2M: Like Class 2 lasers, but dangerous when viewed with optical instruments. The palpebral reflex protects in direct vision. Example: some alignment devices

Class 3R: Moderate risk, power up to 5 times the limit of Class 2 (visible) or Class 1 (invisible). Risk is limited by accidental direct viewing. Example: high-power presentation laser pointers.

Class 3B: Dangerous for direct exposure, power up to 500 mW. Viewing the direct beam is always dangerous, while diffuse reflections are generally safe. Example: research laser.

Class 4: High-power lasers (> 500 mW), very dangerous. They can also cause damage through exposure to diffuse reflections with risk of fire and skin burns. Examples: surgical lasers, industrial cutting lasers.

Specific safety measures are foreseen for each class:

  1. control measures:
  • beam containment,
  • safety interlocks,
  • safety interlocks,
  • protective screens;
  1. administrative measures:
  • signage,
  • operating procedures,
  • staff training,
  • designation of the laser safety manager;
  1. Specific PPE:
  • protective glasses with appropriate filters,
  • protective clothing when necessary,
  • screens and mobile barriers.

ICNIRP guidelines

The ICNIRP (International Commission on Non-Ionizing Radiation Protection) guidelines cover a wide range of radiation, including optical radiation, electric and magnetic fields, and microwave radiation. ICNIRP periodically updates these guidelines to incorporate new scientific knowledge (last updated in 2020).

ICNIRP uses a quantitative exposure-adverse effect approach to develop its guidelines. This approach includes the use of mathematical models and worst-case assumptions to estimate the risks associated with exposure to non-ionizing radiation.