Health Standards Concerning Wireless Power Transfer

Overview of the main international exposure guidelines and standards used to assess the safety of wireless power transfer (WPT) systems.

At a glance

ICNIRP: International exposure guidelines for electric and magnetic fields up to 300 GHz
IEEE C95: Exposure limits and measurement methodologies for electromagnetic field safety
Dosimetric Reference Levels (DRL): Tissue-based exposure limits
Exposure Reference Levels (ERL): External field limits used for compliance testing

ICNIRP Guidelines

The International Commission on Non-Ionizing Radiation Protection (ICNIRP) publishes guidelines that limit human exposure to time-varying electric and magnetic fields. These guidelines are based on scientific research and address biological effects of non-ionizing radiation over the frequency range from static fields up to 300 GHz.

Scope

Exposure to electric, magnetic, and electromagnetic fields
Frequency range up to 300 GHz
Protection of the general public and workers
Evidence-based limits derived from biological effects

Frequency-Dependent Effects

Below 100 kHz: limits primarily address effects on the nervous system
100 kHz to 300 GHz: limits focus on tissue heating and other radio-frequency effects
Both direct and indirect effects of electromagnetic fields are considered

Future Research

Recent ICNIRP reports identify knowledge gaps in the available scientific literature that may influence future updates to radio frequency exposure guidelines.

Reference Levels

fig/ICNIRP2020_Limits.png

Reference levels for time-averaged exposure of the general public from 100 kHz to 300 GHz.

IEEE C95 Standards

IEEE provides recommendations and safety limits for exposure to non-ionizing radiation through the IEEE C95 series of standards. These standards define exposure limits, assessment procedures, and measurement methodologies for electric, magnetic, and electromagnetic fields.

Key Characteristics

Frequency range: 0 Hz to 300 GHz
Applies to: General public and occupational environments
Main framework: Dosimetric Reference Levels (DRL) and Exposure Reference Levels (ERL)
Includes: Electric fields, magnetic fields, and electromagnetic radiation

Dosimetric Reference Levels (DRL)

DRLs define limits within the human body and depend on frequency. Different biological quantities are used in different frequency ranges.

0 Hz – 5 MHz: In-situ electric field strength
100 kHz – 6 GHz: Specific Absorption Rate (SAR)
6 GHz – 300 GHz: Epithelial power density

Although DRLs provide the fundamental protection criteria, they are difficult to measure directly during product development.

Exposure Reference Levels (ERL)

ERLs are practical limits expressed in terms of external electric field strength, magnetic field strength, and incident power density. Compliance with ERLs generally guarantees compliance with the corresponding DRLs.

Measured outside the body
Used in most practical compliance testing
Allow simplified safety verification
May be exceeded if compliance with DRL limits can be demonstrated

Measurement Standards

IEEE Std C95.3
IEEE Std C95.3.1
IEC 62232

Safety Assessment of Wireless Power Transfer Systems

Wireless power transfer systems are typically evaluated against ICNIRP or IEEE exposure limits to ensure safe operation for users. The applicable assessment method depends strongly on the application and transmitted power level.

Biomedical Applications

Usually assessed using SAR-based limits
Direct interaction with the human body
Lower coupling distances generally reduce exposure
Compliance with SAR thresholds is a key design requirement

Industrial and Logistic Applications

Require significantly higher power levels
Generate stronger electric and magnetic fields
Exposure Reference Levels (ERL) are commonly applied
Safety distances may be required under worst-case operating conditions

Engineering Considerations

Field strengths increase with transferred power
Misalignment can affect exposure levels
Shielding can reduce unwanted leakage fields
Compliance verification should be included early in system design

Exposure Reference Levels (ERL)

The figures below illustrate exposure reference levels for unrestricted environments as defined by the IEEE C95 standard.

ERL for unrestricted environments from 0 to 5 MHz.

ERL for unrestricted environments from 100 kHz to 300 GHz.

Comparison of Health Standards

The table below compares the principal organizations and standards used for assessing electromagnetic field exposure in wireless power transfer systems.

Organization	Main Standard	Frequency Range	Primary Focus
ICNIRP	Exposure Guidelines	Up to 300 GHz	Public exposure limits
IEEE	C95.1	0 Hz - 300 GHz	Exposure limits and test procedures
IEEE	C95.3 Series	Application dependent	Measurement methodologies
IEC	IEC 62232	Application dependent	Field measurement and assessment

Sources

Document based on:

A. Cloet, H. Farbakhsh, M. Kleemann, and B. Minnaert, “Recent Advancements in Technologies, Applications, and Regulations of Near-Field Wireless Power Transfer,” in IEEE Access, vol. 14, pp. 49285–49310, 2026, doi: 10.1109/ACCESS.2026.3674000.