This article reviews recent standardization activities and scientific studies related to the assessment of human exposure to electromagnetic fields (EMF). The differences of human exposure standards and assessment of consumer products and medical applications are summarized. First, we reviewed human body modeling and tissue dielectric properties. Then, we explain the rationale of current exposure standards from the viewpoint of EMF and the standardization process for product compliance based on these exposure standards. The assessment of wireless power transfer, as an example of emerging wireless devices, and environmental EMFs in our daily lives are reviewed. Safety in magnetic resonance systems, where the EMF exposure is much larger than from typical consumer devices, is also reviewed. Finally, we summarize future research directions and research needs for EMF safety.

The relationship between skin temperature elevation and incident power density (IPD) from radio-frequency near-field exposure at 28 GHz for different angles of incidence is evaluated computationally in this study. The averaging scheme of the IPD is crucial for determining the maximum allowable exposure levels of wireless equipment to comply with certain standards/regulations. However, it is still unclear which component of the IPD (i.e., the norm or normal component to the human body) is more related the temperature elevation. In the case of four-element dipole arrays, the distances between the model and the antenna were 15 and 30 mm in transverse-electric- and transverse-magnetic-like polarized waves, respectively, and in the case of eight-element dipole arrays, the distances were 45 mm from the center of the array. From our computational results for four- and eight-element dipole arrays, we confirmed that the normal component of the IPD provides better correlation with the surface skin temperature, regardless of angle of incidence, particularly for smaller angles of incidence (<30°). The enhancement of the ratio of the temperature increase to IPD was observed around the Brewster’s angle, which is mainly attributable to the difference in transmittance at the body surface. This exposure scenario may not occur as the antenna–human distance was too large to consider compliance at the closest distance. In terms of output power, the most restrictive condition for compliance is shown to be normal incidence, suggesting the importance of compliance for such exposure scenarios. Furthermore, the absorbed power density proved to be an appropriate metric to monitor in relation to skin temperature elevation.

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This paper presents a quantitative analysis of the differences between the various definitions of spatially averaged power densities ( $sIPD_{s}$ ) for localized exposure to electromagnetic near-fields at frequencies from 6 to 100 GHz. The spatially averaged modulus of the complex Poynting vector ( $sIPD_{mod}$ ) and spatially averaged norm of the real part of the complex Poynting vector ( $sIPD_{norm}$ ) were compared using numerical approaches, where their relationships with the spatially averaged absorbed power density ( sAPD ) and the local peak temperature elevation on skin tissue were analyzed. Our results demonstrated that outside the typical boundary of the reactive near-field, i.e., $> \lambda $ /( $2\pi$ ), which is used as a rough guide of the applicable condition for reference levels in the RF safety guidelines, but at most 10 mm from the radiation source, the maximum difference between $sIPD_{norm}$ and $sIPD_{mod}$ is smaller than 0.7 dB from 6 to 100 GHz. For the appropriate conditions recommended in the RF safety guidelines, the differences between the ratios of sAPD to $sIPD_{s}$ and those for the plane-wave normal incidence, are at most 1.4 dB and 0.9 dB for $sIPD_{norm}$ and $sIPD_{mod}$ , respectively. Under the same condition, the ratios of the temperature rise to $sIPD_{s}$ for the relatively small antennas (total dimension less than $2\lambda$ ) do not significantly exceed that for the plane-wave normal incidence, which means that the expected maximum temperature rise is lower than the temperature rise that is derived from the operational health effect threshold in terms of the temperature rise divided with the reduction factors employed in the RF safety guidelines. The above results provide suggestive evidence that the effect of the definition of $sIPD_{s}$ on the human exposure characteristics is not significant compared with those of the other factors, i.e., the antenna type (size), frequency, distance from the source, and averaging area.

A surrogate model that “learns” the physics of radio wave propagation is indispensable for the efficient optimization of communication network coverages and comprehensive electromagnetic field (EMF) exposure assessments. The capability of a model to predict reasonable outputs given an input that is beyond the data with which the model is trained, namely, “generalizability”, is a fundamental challenge and a key factor for its practical deployment. In this paper, by leveraging the concept of graph neural networks (GNNs), a prediction model for indoor propagation that is “generalized” to not only transmitter positions but also new geometries is presented. We demonstrate that a geometry and a transmitter antenna can be modeled as a graph with all necessary information being included, and a GNN can acquire the knowledge of propagation physics through “learning” from these graphs. We further show that the model can be generalized to new geometry shapes, beyond the shape (square) for model training. We provide useful information on how to obtain an acceptable accuracy for different scenarios. We also discuss the potential solutions to further improve the model’s capability.

Recent progress in wireless technologies has made human exposure to electromagnetic fields (EMFs) increasingly complex. The situation can increase public concerns related to possible health effects due to EMF exposure. Monitoring EMF exposure levels and characterizing them are indispensable for risk communications of human exposure to EMFs. From this background, a project on the acquisition, accumulation, and applications of EMF exposure monitoring data in Japan was started in 2019. One of the objectives of this project is to obtain a comprehensive picture of EMF exposure in actual daily lives. In 2019 and 2020, we measured the electric field (E-field) strength from mainly mobile phone base stations in the same areas as those in measurements conducted in 2006 and 2007 by the Ministry of Internal Affairs and Communications (MIC), Japan, and compared the data to investigate the time-course of the EMF environment. The number of measured points was 100 (10 × 10 grids) in an area of 1 km × 1 km in two urban and two suburban areas, and that in an underground shopping mall was 158. This large-scale study is the first in Japan. As a result, we found that the measured E-field strengths tended to be higher in 2019 and 2020 than those in 2006 and 2007, especially in the mall. However, the median ratios to the Japanese radio wave protection guideline values for urban areas and malls are lower than −40 dB.