Electromagnetic fields at work: what must employers do?

If your shift takes you near an MRI scanner, induction heater or welding cable, you have a right to an assessment that reflects the job you actually do. A low reading is not the whole answer if you have a pacemaker, insulin pump or declared pregnancy. Today, write down the equipment, task and any symptoms, then ask your manager or safety representative what assessment and controls cover your work.

What the law requires

The Control of Electromagnetic Fields at Work Regulations 2016, usually shortened to CEMFAW, apply in England, Wales and Scotland. They came into force on 1 July 2016 under the Health and Safety at Work etc. Act 1974. Northern Ireland has its own regulations.

CEMFAW covers static electric, static magnetic and time-varying fields with frequencies up to 300 GHz. All are non-ionising. Low-frequency fields can stimulate nerves and muscles; radiofrequency fields can heat tissue. Both effects are relevant in the overlapping range of 100 kHz to 10 MHz.

The duties below are in force as at 1 October 2026. We have not identified a scheduled change to these EMF limits. Most employers can demonstrate compliance without additional controls, but must still check for employees at particular risk.

1. Assess exposure. Under regulation 5, you must make a suitable and sufficient assessment of the levels employees may encounter. It must demonstrate compliance with the exposure-limit duty where that duty applies. Use manufacturer data, industry guidance or HSE information where sufficient. Review the assessment if there is reason to suspect it is no longer valid or there has been a significant change.
2. Meet the exposure limits. Regulation 4 requires exposure not to exceed Exposure Limit Values, or ELVs, subject to specific exceptions. Sensory-effect ELVs can be exceeded only with the safety measures required by the relevant Schedule table. These vary by effect, but include temporary exceedance, information for employees and review following reported effects. Health-effect ELVs cannot be exceeded without an applicable statutory or HSE exemption.
3. Make and implement an action plan where required. Regulation 7 applies if your assessment does not demonstrate compliance, unless an exemption disapplies it. Consider lower-exposure methods and equipment, engineering controls, access restrictions, maintenance, layout, exposure duration and suitable protective equipment.
4. Assess and control risks where required. Regulations 8 and 9 apply unless you demonstrate that ELVs are not exceeded, indirect-effect Action Levels are not exceeded and there are no employees at particular risk. Eliminate identified risks or reduce them to a minimum so far as reasonably practicable.
5. Inform and train employees facing identified risks. Regulation 10 covers the assessment findings, controls, safe working practices, indirect effects, how to report sensory or health effects and entitlement to health surveillance and medical examinations.
6. Provide health surveillance and medical examinations when triggered. Under regulation 11, provide these as appropriate if an employee has been exposed above a health-effect ELV and reports a health effect. They must be available during reasonable hours chosen by the employee. Keep suitable records, whatever your workforce size.
7. Record findings if you employ five or more people. Regulation 12 requires records of the significant exposure-assessment findings and, where required, the action plan and significant risk-assessment findings. Smaller employers still have to assess exposure and meet the other applicable duties.

Exposure limits and Action Levels

ELVs are the legal exposure limits for direct effects on the body. Many concern internal quantities, such as the electric field induced in tissue or the rate at which tissue absorbs energy. Others, including static magnetic-field and high-frequency power-density limits, concern external quantities.

Action Levels, or ALs, help you assess exposure using quantities that are easier to measure. If a direct-effect AL is not exceeded, the corresponding ELV is met, subject to the table’s assessment conditions. If it is exceeded, further assessment is needed; that alone does not prove an ELV breach.

Indirect-effect ALs serve a different purpose. They identify levels above which hazards such as implant interference, spark discharge or contact-current burns may occur. Exceeding one triggers a risk assessment and risk controls, even if direct-effect ELVs are met. There is no single reading that proves a workplace safe for everyone.

Use the full Schedule for frequency bands, body areas, averaging periods and measurement conditions. A static-field value is not a substitute for assessing a pacemaker wearer’s exposure to time-varying fields.

Which health effects are covered?

The regulations address short-term direct effects and indirect hazards. Direct effects include nerve and muscle stimulation, tissue heating and burns. Sensory effects include vertigo, nausea, a metallic taste, flickering visual sensations called phosphenes, and auditory sensations from some pulsed fields.

Indirect hazards include interference with implanted or body-worn medical devices, magnetic attraction of ferromagnetic objects, shocks or burns from contact currents, and ignition risks near explosives or flammable atmospheres. These can need controls well below the limits for direct effects.

CEMFAW does not address suggested long-term effects such as cancer. HSE’s guidance says the evidence of a causal relationship is lacking. That does not make a below-ELV result a complete safety assessment: employers must still consider indirect effects, individual susceptibility and their general health and safety duties. Contact with live conductors is outside the CEMFAW risk assessment and belongs under electrical safety controls.

How to assess exposure

Start with HSG281, HSE’s guide to CEMFAW. Table 2 lists low-exposure sources that do not exceed ELVs or indirect-effect ALs. Checking that all equipment and activities employees encounter fit this list can be your exposure assessment. It does not remove the need to consider employees at particular risk.

1. Identify sources and who encounters them. Include normal operation, maintenance and work on other employers’ sites. Check welding sets, induction heaters, MRI equipment, broadcast aerials, radar, RF sealers, rail traction and power distribution. Include ordinary office equipment too, rather than assuming an office is outside the law.
2. Use existing information. Compare the actual equipment and working conditions with HSG281 and manufacturer data. HSG281’s separate tables for pregnancy, passive implants and active devices can flag risks that the general low-exposure list does not resolve.
3. Investigate gaps. A source missing from Table 2 is not automatically dangerous. Obtain relevant manufacturer or industry information. If that is insufficient to demonstrate compliance and no exemption applies, use suitable calculations or measurements. Above a direct-effect AL, assess the corresponding ELV or reduce exposure enough to demonstrate compliance.
4. Check the risk-assessment triggers. You need a regulation 8 assessment if ELVs are not shown to be met, an indirect-effect AL is exceeded or an employee is at particular risk. Consider the frequency, level, duration and distribution of exposure, multiple sources and frequencies, direct and indirect effects, device information and any health-surveillance findings.
5. Record and review. If you have five or more employees, record the significant findings and any required action plan. With fewer, a written record is useful evidence, not a CEMFAW requirement for assessment findings. Revisit the assessment after significant equipment or layout changes, or if reported effects cast doubt on it.

Worked examples at 50 Hz and 27 MHz

Workers who need extra protection

Regulation 2 defines an “employee at particular risk” as someone who has declared a condition that may increase susceptibility to EMF effects, or someone working close to electro-explosive devices, explosive materials or flammable atmospheres. HSE includes declared pregnancy and implanted or body-worn medical devices in the first group.

Devices include pacemakers, defibrillators, insulin pumps, cochlear implants and passive metal implants such as joint replacements, pins and plates. A worker does not need a cardiologist’s warning before you assess risks from a declared passive implant. The possible effects depend on the device and the field.

Give employees a confidential way to tell you about pregnancy or relevant devices, and explain why the information matters. HSE recommends encouraging declarations and obtaining device-manufacturer instructions and relevant medical advice. CEMFAW does not prescribe a medical questionnaire for every induction.

Assessment does not mean automatic exclusion. A device wearer may need a different route past a magnet or restrictions near particular equipment. The 0.5 mT static-field AL is a warning point for active implanted devices, not a guarantee that every device is safe below it. Consider time-varying fields too. For pregnancy, assess the actual task and control identified risks; do not assume every pregnant welder must leave welding work.

Use occupational health where individual advice is needed. Controls may also involve reasonable adjustments for disability, and changes to duties must respect pregnancy discrimination protections. Keep medical information confidential; tell supervisors what restrictions they need to implement, not a worker’s medical history.

How the assessment differs by industry

The numerical limits do not vary by industry. The sources and working conditions do, and some activities have conditional exemptions.

• Welding and induction heating. Assess magnetic fields, relevant contact currents and tasks close to cables or coils, including fault-finding. Consider layout, cable routing and distance. Follow source-specific guidance; ordinary gloves do not shield a worker from magnetic fields.
• Healthcare and MRI. Consider static magnetic fields, switched gradient fields and RF exposure, as well as implant interference and projectile hazards. Porters, cleaners and healthcare assistants entering scanner rooms need to be covered too. Medical MRI has a conditional exemption, but it does not remove risk controls or training duties.
• Power distribution. Check electric and magnetic fields around lines and substations, plus spark discharge and contact currents. Maintenance can bring workers much closer to sources than routine access.
• Broadcasting, radar and telecoms. Assess RF exposure, operating power and access to antennas. Rooftop or mast work may need exclusion zones, permits and coordination with the operator. Being outside a designated exclusion zone is different from working beside an active transmitter.
• Rail. Include traction equipment and relevant depot activities. Share exposure information between the site operator, contractors and each worker’s employer.

High-frequency limits also depend on averaging. At 28 GHz, the power-density limit is 50 W/m² averaged over any 20 cm² and over 68 ÷ 28^1.05, approximately 2.1 minutes. The 1 cm² spatial maximum must not exceed 20 times 50 W/m², or 1,000 W/m². Pulse conditions can also apply. A compliant time average alone is not permission to ignore hotspots or other risks.

Managing exposure day to day

Use HSG281’s equipment tables for screening, then its assessment and control guidance for the tasks that need more work. Reduce exposure at source where possible. Replacement equipment, layout changes, suitable screening and interlocks may avoid reliance on people remembering to keep their distance. Screening is not equally effective for every frequency or source.

Where access restrictions are needed, define the areas and explain the rules to employees and contractors. Maintain equipment and reassess changes that could affect emissions. Any protective equipment must suit the identified hazard, with training in its use. Keep the assessment and safety records where the people managing the work can find them.

If you work near a strong source, follow the access and operating instructions. Report tingling, unexpected warming, vertigo, visual effects or suspected device interference to your employer. If you have an implant or body-worn device, ask for an individual assessment rather than relying on colleagues’ exposure limits.

After a long shift, note the source, task, location, date and symptoms. Ask your manager or safety rep for the assessment and controls for your task or route. If you have a medical device or have declared pregnancy, ask for a confidential individual assessment; you do not have to measure the field yourself. A union safety rep can press for worker involvement. UNISON, Unite and GMB represent workers across health, care, logistics and warehouses. If the employer will not address a safety concern, report it to the HSE; in Northern Ireland, contact HSENI. If you face an immediate risk, ask for controls now.

Exemptions for MRI, military activities and other work

You cannot grant an exemption to an employee. The legal routes concern work activities and have conditions. Temporary sensory-effect exceedance under the Schedule is a separate permission, not a blanket exemption.

• Medical MRI. Regulation 4 covers development, testing, installation, use, maintenance and related research involving MRI equipment for patients in the health sector. Exposure must be as low as reasonably practicable and employees protected against health effects and safety risks. The exemption is not limited to scanning patients, and does not automatically cover unrelated research MRI.
• Military activities. The activity must have a suitable and sufficient alternative exposure limitation system. The provision can cover service personnel, civilians working with them and activities on specified defence premises. Military employment alone does not establish an exemption.
• HSE certificates. Regulation 13 permits time-limited exemptions for specified work activities. Check the applicable certificate, its period of validity and every condition. If an activity is already covered, no individual business application is needed. A request to add an activity is a different process.

HSE’s exemption guidance explains that these routes can disapply both the exposure-limit duty and the regulation 7 action-plan requirement. Exposure assessment, risk assessment, risk reduction, relevant information and training, and other applicable duties remain. For certificate-covered work, calculations or measurements to demonstrate ELV compliance are not required. You still need sufficient information to assess and control risks.

Employees, agency staff and contractors

CEMFAW’s specific duties protect an employer’s employees while at work, including part-time and fixed-term employees and apprentices. Do not assume that everyone on a site is legally the host’s employee. Agency and host employers must coordinate exposure information and controls according to their roles; a worker’s employment status does not remove the site’s general safety responsibilities.

Non-employee workers and contractors also have protection under general health and safety law, including duties towards people who are not employees. A self-employed person without employees does not owe CEMFAW employer duties to themselves, but may have other health and safety duties and must follow site controls. See contractor safety duties.

The shipping exclusion is limited. Regulation 3 excludes masters, crews and their employers in respect of normal shipboard activities carried out solely by the crew under the master’s direction. It does not exclude every task on a ship, and naval ships are outside this exclusion. Regulation 14 also extends CEMFAW to specified work outside Great Britain, so offshore work needs a scope check.

Northern Ireland

The Control of Electromagnetic Fields at Work Regulations (Northern Ireland) 2016, SR 2016 No. 266, came into force on 1 August 2016 under the Health and Safety at Work (Northern Ireland) Order 1978. They use the same AL and ELV values, but are a separate legal instrument.

HSENI and district councils enforce the applicable duties. The regulations have a separate offshore Schedule and give the exemption power to HSENI. Do not assume an HSE certificate automatically covers work in Northern Ireland. Our Northern Ireland guide explains other differences in workplace law.

Questions people ask

What counts as dangerously high EMF?

There is no single number. Frequency, exposure type, duration and the worker’s susceptibility matter. Exceeding a direct-effect AL calls for further assessment; it does not itself prove an ELV breach, even above a High AL. Below direct-effect limits, implants and other indirect hazards can still need controls.

Do we need an EMF consultant or meters?

Usually not for a straightforward low-exposure workplace. HSG281 and relevant manufacturer information may be enough. Obtain specialist help if the available information cannot support a suitable assessment, particularly for complex sources or close-proximity work.

Does office Wi-Fi or a phone mast on the roof need assessment?

Both belong in the exposure assessment. HSG281 lists ordinary Wi-Fi among low-exposure sources but flags special consideration for active implants. Base-station antennas outside the operator’s designated exclusion zone are also listed. Maintenance or roof access inside that zone needs a separate check of the task and controls.

What must an employer do for someone with a pacemaker?

Assess the person’s exposure and the device’s susceptibility, even if general ELVs are met. Obtain device instructions and appropriate medical advice. Consider static and time-varying fields, then put any needed restrictions or adjustments in place. The 0.5 mT static-field AL is not a universal pacemaker safety boundary.

Can a pregnant employee work near strong fields?

That depends on the assessment. Declared pregnancy requires particular consideration, not automatic exclusion. Identify the risks in the actual task, eliminate or control them and consider changes to work where necessary. HSE’s pregnancy-specific equipment table can help identify sources needing closer attention.

When is health surveillance required?

Under CEMFAW regulation 11, an employee must have been exposed above a health-effect ELV and reported a health effect. Provide health surveillance and medical examinations as appropriate during reasonable hours chosen by the employee, and keep suitable records. Do not wait for that trigger before investigating reported symptoms or reviewing questionable controls.

Sources

1. The Control of Electromagnetic Fields at Work Regulations 2016, legislation.gov.uk. Regulations 2 to 14 cover scope, duties and exemptions.
2. CEMFAW Schedule: Action Levels, Exposure Limit Values and safety conditions, legislation.gov.uk.
3. The Control of Electromagnetic Fields at Work Regulations (Northern Ireland) 2016, legislation.gov.uk.
4. HSG281: Electromagnetic fields at work, a guide to the Control of Electromagnetic Fields at Work Regulations 2016, HSE. Equipment tables, assessment, particular-risk workers and controls.
5. Exemptions from EMF exposure limits, HSE. Conditions and duties that remain.
6. Health & Safety Representatives Survey 2024–2025, TUC, published 5 January 2026. Safety-representative involvement in risk assessments.
7. Occupational exposure of healthcare and research staff to static magnetic stray fields from 1.5–7 Tesla MRI scanners is associated with reporting of transient symptoms, Schaap et al., Occupational and Environmental Medicine (2014). Study of staff at 14 MRI facilities.
8. Raise a health and safety concern, HSE.
9. Contact HSENI, Health and Safety Executive for Northern Ireland.