Electromagnetic fields

Sources of exposure and effects

• Static fields. Magnetic resonance equipment, electrolysis, industrial magnets and levitation trains; sensory effects due to movement in the field and risk of projection of ferromagnetic objects and interference with implants.
• Low frequency (up to 100 kHz). Electrical lines and substations, transformers, induction furnaces, resistance and arc welding, demagnetizers; nerve and muscle stimulation and sensory effects.
• Intermediate frequency and radio frequency. Dielectric and induction heaters, electronic security systems, diathermy equipment; thermal and stimulation effects according to frequency.
• Microwaves and high frequency (up to 300 GHz). Telecommunications antennas, radars, drying equipment and industrial microwave ovens; heating of tissues and body surfaces.
• Indirect effects. Interference with pacemakers, defibrillators, insulin pumps and passive implants, contact currents, ignition of flammable atmospheres and detonation of explosives.
• Particularly vulnerable groups. Pregnant workers and people with medical implants, for whom general limits may not be sufficient.

Obligations of Royal Decree 299/2016

The employer must assess the risks arising from exposure to electromagnetic fields, identifying the sources, exposure levels, and affected individuals, using measurements or calculations when exceeding action levels cannot be ruled out based on information from the manufacturer, databases, or available guidelines. Exposure limit values ​​are defined based on internal quantities (electric field induced in the body, specific absorption rate, power density) and distinguish between those related to health effects, which cannot be exceeded, and those related to sensory effects, which can be temporarily exceeded under specific conditions and measures. Action levels are values ​​of external quantities (electric field, magnetic field, contact current) that facilitate demonstrating compliance without dosimetric calculations.

When action levels are exceeded, the employer must develop and implement an action plan with technical and organizational measures: alternative work methods, lower-emission equipment, shielding and interlocking, area demarcation and signage, limitation of exposure duration, and appropriate maintenance and personal protective equipment. Specific measures must be taken for pregnant workers and people with implants, and staff must be informed and trained on the assessment results, limit values, measures, and the detection of adverse effects. Health surveillance must also be ensured, with medical examinations when an adverse effect is reported or a limit value is exceeded. Magnetic resonance imaging (MRI) facilities and certain activities may exceed limit values ​​under enhanced conditions and safeguards.

Practical assessment and measures

• Identification of sources. Inventory of emitting equipment and facilities, with their frequencies and power levels, and classification according to the possibility of exceeding action levels.
• Simplified assessment. Use of the tables from the INSST technical guide and the European guide that identify equipment that complies without the need for measurements.
• Measurements and calculations. Carried out by competent personnel with appropriate instrumentation at the positions and sources that require it, with comparison with action levels and, if appropriate, dosimetric evaluation.
• Zoning. Delimitation and signage of restricted access zones, prohibition of access to people with implants and control of ferromagnetic objects in static fields.
• Technical and organizational measures. Shielding, distance, interlocks, reduction of exposure time and work procedures.
• Registration and review. Documentation of the assessment, review in case of changes in equipment, facilities or people, and recording of exposures and incidents.

Organizational application: how to manage exposure to electromagnetic fields

1. Inventory the sources of electromagnetic fields present in the company, with their technical characteristics and the people who work in their environment.
2. Perform the initial assessment using the tables and criteria from the INSST technical guide and information from manufacturers, and determine which sources require measurements or calculations.
3. Assign measurements to competent personnel with appropriate instrumentation, compare with action levels and limit values, and document the results.
4. Prepare the action plan when action levels are exceeded, with technical measures (screening, distance, interlocking), organizational measures (zoning, times, procedures) and signage.
5. Identify and protect pregnant workers and people with implants, with access restrictions and job adaptations.
6. Inform and train staff, integrate specific health surveillance and establish the procedure for reporting adverse effects.
7. Review the assessment in response to changes in equipment, facilities, or exposed personnel and maintain records.

Preventive management software allows you to maintain an inventory of emission sources and equipment, link them to exposed positions and people, record measurements and action plans, manage access restrictions for particularly sensitive people, schedule training and health monitoring, and maintain traceability of assessments.

Limits and common mistakes

1. Ignoring the assessment on the grounds that it only affects large electrical or telecommunications installations, when equipment such as resistance welding or induction furnaces can exceed action levels.
2. Do not identify people with implants or pregnant workers in areas with relevant exposure.
3. Performing measurements without competent personnel or adequate instrumentation, or without relating them to the action levels of each frequency.
4. Confusing long-term effects, not covered by the regulation, with the direct and indirect effects that it does regulate.
5. Do not mark or delimit restricted access areas or control ferromagnetic objects in static fields.
6. Do not review the assessment after the addition of new equipment or changes to the facilities.

The specific evaluation depends on the sources, frequencies, and working conditions; this sheet is for informational purposes only.

Regulatory and reference framework

• Royal Decree 299/2016, of July 22. Protection of the health and safety of workers against risks related to exposure to electromagnetic fields.
• Directive 2013/35/EU . Minimum health and safety requirements concerning the exposure of workers to risks arising from physical agents (electromagnetic fields).
• INSST. Technical guide for the assessment and prevention of risks arising from exposure to electromagnetic fields in the workplace (2019) . Criteria for the application of Royal Decree 299/2016.
• Law 31/1995, of November 8. Law on the Prevention of Occupational Risks.
• Royal Decree 39/1997, of January 17. Regulation of Prevention Services; risk assessment and health surveillance.
• Royal Decree 485/1997, of April 14. Safety and health signage at work; signage of areas with electromagnetic fields.

Royal Decree 299/2016 does not cover the possible long-term effects of exposure or the risks arising from contact with live conductors, which are governed by electrical risk regulations .