What are the UK Exposure Limits and Policy? Government policy on EMFs in the UK was formed with advice from the UK Health Security Agency( UKHSA) and Stakeholder Advisory Group on ELF EMFs( SAGE). The policy for high voltage overhead lines has two key pillars: compliance with the International Commission on Non-Ionizing Radiation Protection( ICNIRP) exposure limits in terms of the 1999 EU Recommendation and a precautionary policy called“ optimal phasing”.
Pillar 1- General Public Exposure Limits
• An electric field of 9 kV / m
• A magnetic field of 360 µ T
Both apply where the time of exposure is significant e. g. residential properties, and properties where members of the public spend an appreciable proportion of their time.
Pillar 2- Precautionary Measure
• High voltage overhead lines – optimum phasing.
Phasing is the way the circuits on the two sides of the pylon are wired relative to each other( see diagram below). When transposed( optimally phased) the magnetic field reduces more quickly with distance compared to untransposed overhead lines.
What about Occupational Exposure Limits? There are statutory regulations for occupational exposure. In the UK these are The Control of Electromagnetic Fields at Work Regulations 2016( CEMFAW) which implement the EU Directive and are based on the values from ICNIRP 2010. The article in Radiation Protection Today Spring 2025 has more information on this.
Are EMFs from the Electricity System Harmful? Though the balance of evidence is against there being any effect on human health from exposure to EMFs, there is some scientific uncertainty suggesting a possible link between unusually high exposures to magnetic fields and childhood leukaemia. Based on this, magnetic fields are classed by the World Health Organisation( WHO) as ' possibly ' carcinogenic.
Given the uncertainty, precautionary measures along with the exposure limits ensure that both established and possible health effects are considered.
The electricity system is designed to ensure that all assets comply with the government EMF policies and guidelines set by authoritative and independent experts.
For more information on EMFs from the electricity industry please visit www. emfs. info
National Grid also runs an EMF helpline on 0845 7023270 or 01926 653382.
Diagram showing phasing of pylons
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