Exposure limits and policy

UK occupational exposure limits

Unlike public exposures, there are statutory regulations for occupational exposure. The regulations in force in the UK are The Control of Electromagnetic Fields at Work Regulations 2016 (“the Regulations”) which implement the EU Directive 2013 and are based on the values from ICNIRP 2010.

The Regulations ensure that employers have taken reasonable steps to prevent harm in the workplace from exposure to electric and magnetic fields (EMFs).

The structure of the Regulations can seem quite complex, but there are a series of steps, which are described in the ‘what do you have to do’ tab, below.

For occupational exposure for employees who are not deemed to be at particular risk, sensory and health exposure limits apply. The first stage of assessment is against Sensory Effect limits, which cover transitory effects of EMFs (once you move away from the field, the effects go away).

Sensory effects

Exposure Limit Value (Table ELV3)

140 mV/m peak

Low Action Level (Tables AL1 and AL2)

Magnetic field: 1 mT (18 mT for exposure only to limbs)
Electric field: 10 kV/m

The Sensory Effects Exposure Limit Value is the limit of the induced voltage within the body, which cannot be physically measured in practice. Dosimetry calculations are performed using conservative assumptions to work out what external EMF exposure would ensure compliance with the Exposure Limit Value. Exposures above the Low Action Levels do not automatically mean that the Exposure Limit Values are exceeded, but further work is required to demonstrate compliance. The Low Action Level for electric fields is set to avoid hazardous spark discharges.

Providing the Low Action Levels are complied with, the Regulations allow temporary exposure up to a higher value (the Health Effects Exposure Limit Values). See the “What do you have to do?” section, below, for the full list of conditions.

The High Action Levels, given below, have been derived from the Health Effects Exposure Limit Values using conservative assumptions, and so compliance with the High Action Levels will guarantee compliance with the corresponding Health Effects Exposure Limit Values.

Health effects

Exposure Limit Value (Table ELV2)

1100 mV/m peak

High Action Levels (Tables AL1 and AL2)

Magnetic field: 6 mT (18 mT for exposure only to limbs)
Electric field: 20 kV/m

Again, if the High Action Levels are exceeded, it does not necessarily mean that the Health Effects Exposure Limit Values are exceeded. Compliance with the Health Effects Exposure Limit Values can be determined by calculation, if necessary.

What do you have to do?

If you are an employer, the Regulations require you to apply the following steps:

You must comply with the Health Effects Exposure Limit Values. Regulation 4(1)
1. You can use the High Action Levels to assess compliance with the Health Effects ELV. Regulation 5(2)(b)
You can exceed the Sensory Effects Exposure Limit Values Regulation 4(2) as long as:
1. They are only exceeded temporarily.
2. Hazardous spark discharges and contact currents in excess of 1 mA are prevented through the provision of information and training and the use of suitable technical and personal protection measures.
3. Adequate information is provided to the employee on the possibility of sensory effects related to time-varying magnetic fields, including retinal phosphenes.
4. Where any of those sensory effects are reported to the employer, the risk assessment is updated where necessary. Table ELV3
You must perform an Exposure Assessment. Regulation 5
You need a risk assessment only if you exceed the Sensory Effects Exposure Limit Values, or if indirect effects are an issue, or if you have staff at particular risk. Indirect effects means:
1. Electric fields above the Low Action Level, 10 kV/m at 50 Hz. Table AL1
2. Contact currents above the relevant Action Levels. Table AL5
3. Static magnetic fields high enough to interfere with medical devices or cause a projectile risk. Table AL6
You need an Action Plan only if you exceed the Sensory Effects Exposure Limit Values. Regulation 7
You must provide information and training. Regulation 10
You must provide "appropriate" health surveillance and medical examinations to staff who exceed the Health Effects Exposure Limit Values and report experiencing a health effect. Regulation 11
There are exemptions for military and MRI Regulation 4(3), and the Health and Safety Executive (HSE) can issue further exemptions. Regulation 13

(Please note this is just a summary and is specific to 50 Hz.)

Employees at particular risk

The Regulations require employers to give special consideration to the safety of employees at particular risk. This is required even if you are compliant with the exposure limits.

Employees at particular risk are defined into two categories:

This does not mean that the employee is necessarily at more risk, but that an assessment should be completed to identify and mitigate any specific risks.