The EMF question employers need to ask
Most companies do not start thinking seriously about electromagnetic fields because someone found an EMF clause in a safety manual. More often, the issue becomes real when a valued employee returns to work with a pacemaker or implantable cardioverter-defibrillator (ICD) and asks a simple question: Can I safely go back to my job
Answering that question requires understanding an important distinction: the EMF limits used to protect workers generally are not the same thing as the thresholds relevant to interference with an implanted medical device.
In many manufacturing and industrial environments, the predominant EMF concern is low-frequency electric and magnetic fields associated with 50/60 Hz power systems, welding equipment, motors, buswork and other high-current equipment. Occupational exposure criteria for these fields are available through guidance such as the ACGIH Threshold Limit Values and ICNIRP’s low-frequency guidelines. At higher frequencies, Health Canada’s Safety Code 6 specifies recommended human-exposure limits for radiofrequency fields from 3 kHz to 300 GHz.
These are human-exposure criteria. They are intended to protect people from established adverse effects of electromagnetic fields, not to establish electromagnetic compatibility of an implanted medical device.
For a worker with a pacemaker or ICD, there is an additional and more specific question: could the electromagnetic field interfere with the device?
A pacemaker or ICD contains sensitive circuitry that monitors electrical activity in the heart. Under some conditions, an external electromagnetic field can be interpreted by the device as cardiac activity or electrical noise. Depending on the device and the type of interference, the result can include temporary inhibition or alteration of pacing, a change in pacing mode, or inappropriate detection and therapy by an ICD.
Importantly, this can occur at field levels below limits intended to protect the human body. ICNIRP’s 2010 low-frequency guidelines explicitly note that compliance with its exposure guidelines may not prevent interference with pacemakers and implanted defibrillators, and that pacemaker interference can occur below its reference levels.
That is why an employee with an active implantable medical device, or AIMD, may require a different kind of assessment.
The concern is especially relevant around high-current and strong-field equipment such as arc and resistance welding, induction heating and hardening systems, power distribution equipment, large conductors and buswork, and some RF sources.
With arc welding, for example, the welding leads and return-current path can be significant sources of magnetic field. Cable routing and how closely those conductors pass the worker’s body can materially affect exposure.
There is no universal “safe distance” that works for every worker and every implant. Manufacturer recommendations are useful and, in some cases, may be enough to screen a task. But the answer can depend on the specific device, its programming and lead configuration, the worker’s clinical dependence on the device, the frequency and waveform of the field, equipment current or load, and the worker’s actual position while doing the job.
This is where the cardiologist or device clinic and the workplace need each other. Cardiologists often recognize the potential for workplace interference and may be the ones recommending that an employer have the environment assessed. What they generally cannot know is the field strength beside a particular welding cable, induction coil or electrical cabinet under operating conditions. Likewise, the employer or safety professional should not be making assumptions about the worker’s cardiac device without appropriate clinical or manufacturer input.
A good assessment brings those pieces together.
Standards such as the EN 50527 series provide a framework specifically for assessing workers with active implanted medical devices, including separate procedures for workers with pacemakers and ICDs.
The process starts with the equipment, the task and the available device information. Where the risk cannot be ruled out through manufacturer guidance or an initial review, task-specific onsite measurement may be warranted. Measurements should reflect the equipment operating as it is actually used and the positions the worker actually occupies, including realistic close approaches and body posture.
For the employer, a return-to-work situation involving a pacemaker or ICD may engage both workplace safety obligations and the duty to accommodate.
Where uncertainty remains, onsite measurements can provide objective evidence to help determine whether the worker can return without restriction or whether practical controls such as separation distance, cable routing, altered work position or task modification are appropriate.
EMF Safety Canada performs onsite EMF assessments for workers with pacemakers, ICDs and other active implanted medical devices, providing employers and healthcare professionals with exposure data to help inform safe, reasonable and evidence-based return-to-work decisions.
