Effect of adverse environmental conditions and protective clothing on temperature rise in a human body exposed to radiofrequency electromagnetic fields

Moore, Stephen; McIntosh, R.; Iskra, Steve; Lajevardipour, Alireza; Wood, Andrew W.

doi:10.1002/bem.22048

Cited by 7 publications

(5 citation statements)

References 18 publications

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“…Limits on whole-body exposure are designed to take into account the total heat load on the human body from exposure at these frequencies. Only two studies considered here have reported changes in core body temperature from whole body exposures, and only up to 6 GHz (Hirata et al, 2013;Moore et al, 2017).…”

Section: Whole-body Exposuresmentioning

confidence: 99%

“…As in comments in section 5.3, most of the computational studies reported here assume an ambient (or environmental) temperature of around 22 °C-28 °C (room temperature). In a modeling study, Moore et al (2017) investigated the effects of exposure to RF energy in environments with elevated temperatures and high relative humidity, considering situations where heavy protective clothing must be worn. One scenario assumed exposure to RF energy at 6 GHz in an environment with ambient temperature of 38 °C and relative humidity of 60% (nearly an intolerable environment, with a 'heat index' value on the threshold of 'extreme danger').…”

Section: Whole-body Exposuresmentioning

confidence: 99%

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Human exposure to radiofrequency energy above 6 GHz: review of computational dosimetry studies

et al. 2021

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International guidelines/standards for human protection from electromagnetic fields have been revised recently, especially for frequencies above 6 GHz where new wireless communication systems have been deployed. Above this frequency a new physical quantity 'absorbed/epithelial power density' has been adopted as a dose metric. Then, the permissible level of external field strength/power density is derived for practical assessment. In addition, a new physical quantity, fluence or absorbed energy density, is introduced for protection from brief pulses (especially for shorter than 10 s). These limits were explicitly designed to avoid excessive increases in tissue temperature, based on electromagnetic and thermal modeling studies but supported by experimental data where available. This paper reviews the studies on the computational modeling/dosimetry which are related to the revision of the guidelines/standards. The comparisons with experimental data as well as an analytic solution are also been presented. Future research needs and additional comments on the revision will also be mentioned.

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Section: Whole-body Exposuresmentioning

confidence: 99%

Section: Whole-body Exposuresmentioning

confidence: 99%

Human exposure to radiofrequency energy above 6 GHz: review of computational dosimetry studies

et al. 2021

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“…No previous studies evaluated the temperature elevation in human head models for local exposure while considering thermoregulation. It should be noted that several studies computed the temperature elevation for whole-body exposures [ 14 – 18 ].…”

Section: Introductionmentioning

confidence: 99%

Temperature elevation in the human brain and skin with thermoregulation during exposure to RF energy

2018

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BackgroundTwo international guidelines/standards for human protection from electromagnetic fields define the specific absorption rate (SAR) averaged over 10 g of tissue as a metric for protection against localized radio frequency field exposure due to portable devices operating below 3–10 GHz. Temperature elevation is suggested to be a dominant effect for exposure at frequencies higher than 100 kHz. No previous studies have evaluated temperature elevation in the human head for local exposure considering thermoregulation. This study aims to discuss the temperature elevation in a human head model considering vasodilation, to discuss the conservativeness of the current limit.MethodsThis study computes the temperature elevations in an anatomical human head model exposed to radiation from a dipole antenna and truncated plane waves at 300 MHz–10GHz. The SARs in the human model are first computed using a finite-difference time-domain method. The temperature elevation is calculated by solving the bioheat transfer equation by considering the thermoregulation that simulates the vasodilation.ResultsThe maximum temperature elevation in the brain appeared around its periphery. At exposures with higher intensity, the temperature elevation became larger and reached around 40 °C at the peak SAR of 100 W/kg, and became lower at higher frequencies. The temperature elevation in the brain at the current limit of 10 W/kg is at most 0.93 °C. The effect of vasodilation became notable for tissue temperature elevations higher than 1–2 °C and for an SAR of 10 W/kg. The temperature at the periphery was below the basal brain temperature (37 °C).ConclusionsThe temperature elevation under the current guideline for occupational exposure is within the ranges of brain temperature variability for environmental changes in daily life. The effect of vasodilation is significant, especially at higher frequencies where skin temperature elevation is dominant.

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“…In the current situation, the rationale for exposure limits and guidance relies on the Adair and Berglund model. This can be done with quite some confidence, since more recent and more detailed RF exposure modeling studies have confirmed their thermal predictions [32][33][34][35][36][37]. Children have a 4 Concepts in Magnetic Resonance Part B Less than 10% of the examinations is performed with SA > 3 kJ/kg.…”

Section: Core Temperature Predictionsmentioning

confidence: 92%

Thermal Effects Associated with RF Exposures in Diagnostic MRI: Overview of Existing and Emerging Concepts of Protection

Brink

Stender²

2019

Concepts in Magnetic Resonance Part B

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Apart from magnetic attraction risks, the primary biophysical concern associated with MRI is radiofrequency heating of the human body and associated discomfort, health deterioration, or potential burns. This paper reviews experimental data and numerical modeling of systemic (core and brain) temperature and local thermal effects associated with diagnostic MRI exposures at 1.5T (64 MHz) and 3.0T (128 MHz). Allowable temperatures and duration of systemic exposure are established based on knowledge of (short-term) human thermobiology. Longer term effects related to DNA damage or altered cellular pathways are not covered in this review. Updated limits are proposed for core temperature increase (≤1.3°C) and for Specific Absorption (<4 kJ/kg). The potential use of thermal dose (CEM43) for local thermal protection is described, and previously proposed exposure limit values are evaluated against available data from current MRI practice. Gaps in knowledge are identified, and recommendations for additional research are provided.

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Effect of adverse environmental conditions and protective clothing on temperature rise in a human body exposed to radiofrequency electromagnetic fields

Cited by 7 publications

References 18 publications

Human exposure to radiofrequency energy above 6 GHz: review of computational dosimetry studies

Human exposure to radiofrequency energy above 6 GHz: review of computational dosimetry studies

Temperature elevation in the human brain and skin with thermoregulation during exposure to RF energy

Thermal Effects Associated with RF Exposures in Diagnostic MRI: Overview of Existing and Emerging Concepts of Protection

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