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Short answer: Electromagnetic interference (EMI) is an electromagnetic disturbance that degrades the performance of electrical or electronic equipment. In labs and clinics the practical concern is twofold: equipment must tolerate disturbances from its surroundings (immunity), and it must not emit disturbances that upset other equipment or radio services (emissions). This page sets out how FDA, the FCC and the IEC standards each use the vocabulary, so you can read device documentation and facility guidance consistently.
This is general reference information, not advice on any specific device, facility or incident.
Definition and scope
FDA’s guidance on electromagnetic compatibility (EMC) of medical devices, issued June 6, 2022, defines EMC as the ability of a medical device to function safely and effectively in its intended electromagnetic environment, “including immunity to EM disturbances (i.e., interference), without introducing excessive EM disturbances (i.e., emissions) that might interfere with other equipment.” In that framing, interference is the disturbance as experienced by the affected equipment, immunity is the protection against it, and emissions are what the device itself puts out.
FDA lists radio waves, power surges, radiofrequency (RF) disturbances and electrostatic discharge (ESD) as examples of disturbances that can cause unacceptable degradation. It also states that interference can cause medical devices to not perform as intended and lead to hazardous situations, such as delays or errors in diagnosis, treatment or monitoring.
Where EMI comes from in practice
FDA’s recommendations for EMC and EMI in healthcare facilities name the following sources: common hand-held RF transmitters (for example cellular and PCS telephones and two-way radios), equipment used in intense electromagnetic environments such as near ambulance radios or in electrosurgery, and RF transmitters and all electrical and electronic equipment, including medical devices themselves. The same page frames the problem as a facility-level one, not only a device-level one.
The textbook description of EMI as a source, a coupling path and a receiver, and its split into conducted and radiated interference, is standard engineering background. Introductory material on this is available in What Is Electrical Engineering?; the sourced material below concerns how regulators and standards use the terms.
Same problem, three vocabularies
| Source | Term | What the source says |
|---|---|---|
| FDA, EMC of Medical Devices (June 6, 2022) | EMC, immunity, emissions | EMC is the ability to function in the intended electromagnetic environment, including immunity to disturbances, without introducing excessive emissions. Emissions limits are established to protect radio services and minimize interference to other equipment, both medical and non-medical. |
| 47 CFR 15.3(m), FCC | Harmful interference | Any emission, radiation or induction that endangers the functioning of a radio navigation service or other safety services, or seriously degrades, obstructs or repeatedly interrupts a radiocommunications service operating under that chapter. |
| 47 CFR 15.3(o), (z), (n), FCC | Intentional, unintentional and incidental radiators | Three classes of device by how they generate RF energy (see next section). |
The practical consequence is that “interference” is not one legal threshold. Under FDA’s EMC guidance it describes any disturbance that degrades a device; under the FCC rule, “harmful interference” is a narrower category tied to radio services and safety services.
Types of radiator under FCC rules
| Class (47 CFR 15.3) | Definition in the rule |
|---|---|
| Intentional radiator | A device that intentionally generates and emits radio frequency energy by radiation or induction. |
| Unintentional radiator | A device that intentionally generates RF energy for use within the device, or sends RF signals by conduction to associated equipment via connecting wiring, but is not intended to emit RF energy by radiation or induction. |
| Incidental radiator | A device that generates RF energy during its operation although it is not intentionally designed to generate or emit it. |
Where it matters for labs and clinics
Two standards families are named in FDA’s EMC guidance by equipment type: the IEC 60601 and 80601 series applies to medical devices that apply or transfer energy to a patient, and IEC 61010-1 applies to electrical laboratory equipment. See EN IEC 60601-1-2: the EMC standard for medical electrical equipment and IEC 61010-1: the lab equipment safety standard for each.
FDA’s healthcare-facility recommendations are a useful checklist for any site that runs sensitive electronics:
- Assess the facility’s electromagnetic environment and identify areas that hold critical devices, such as the emergency room, intensive care and neonatal intensive care.
- Coordinate the purchase, installation and servicing of electrical and electronic equipment.
- Educate staff, contractors, visitors and patients about EMI.
- Establish and implement written policies and procedures.
- Report EMI problems to the FDA MedWatch program.
Research instruments that measure very weak signals are a related case. Biomagnetic measurement is one example, described in magnetoencephalography (MEG); see also EEG vs MEG.
Common misunderstandings
Is EMI only a radio problem?
No. FDA’s list of disturbances includes power surges and electrostatic discharge as well as radio waves and RF disturbances.
Is it only the receiving device that matters?
No. FDA’s definition of EMC covers both immunity of the device and the emissions it introduces into the environment.
Does “interference” always mean regulatory “harmful interference”?
No. Harmful interference is a defined term in 47 CFR 15.3(m), limited to disturbances that endanger or seriously degrade radio navigation, safety services or radiocommunications services.
FAQ
What does EMI stand for?
Electromagnetic interference. FDA’s guidance uses “EM disturbances (i.e., interference)” for the same idea.
What is the difference between EMI and EMC?
EMI is the disturbance. EMC is the ability of equipment to function in its electromagnetic environment, including immunity to interference and not introducing excessive emissions.
Can EMI affect medical devices?
FDA states that interference can cause medical devices to not perform as intended and lead to hazardous situations, such as delays or errors in diagnosis, treatment or monitoring.
Where should an EMI problem with a medical device be reported?
FDA’s healthcare-facility recommendations say to report EMI problems to the FDA MedWatch program.
Sources
- FDA, Electromagnetic Compatibility (EMC) of Medical Devices, guidance issued June 6, 2022 (nonbinding): https://www.fda.gov/media/94758/download (read 2026-11-08)
- FDA/CDRH, Recommendations for EMC/EMI in Healthcare Facilities: https://www.fda.gov/radiation-emitting-products/electromagnetic-compatibility-emc/fdacdrh-recommendations-emcemi-healthcare-facilities (read 2026-11-08)
- 47 CFR 15.3, Definitions: https://www.law.cornell.edu/cfr/text/47/15.3 (read 2026-11-08)
