EMF Exposure: Comparison
Please note this is a comparison between Version 1 by Adel Razek and Version 2 by Conner Chen.

In different situations, electromagnetic fields (EMF)s are consumed every day in several sociable purposes. Additionally, they are employed securely in medical treatments. Conversely, when these fields are operated inadvertently, it can crop unfavorable outcomes. These consequences are intimately linked to the type of the EMF and the exposed substance. The strength of the field as well as its frequency typify EMF, whereas the physical and geometric properties describe matter.

  • EMF exposure
  • safety standards
  • medical device integrity

1. Introduction

Through the growth in the exercise of electromagnetic fields (EMF) in everyday life, various investigation works concerning their consequences have been dedicated in different domains. One of the most significant concerns is in the health domain. Studies have focused on the effects of electromagnetic (EM) sources on humans and health care devices. Two questions generally guide assessments of the effects of exposure to electromagnetic fields. The first is to assess induced fields in the tissues and physical consequences to assess possible health effects according to international safety standards [1][2][3][1,2,3]. The second challenge is to assess the risk of disruption of medical devices, integrated or associated with the body, used in therapy or involved in interventions.
Concerning the body tissues’ exposure to the EMF atmosphere, the international health safety standards relative to exposure to external EMF are an established function with different parameters. These include, furthermore to the field characters (strength and frequency) and the interval, the tissue density and its physical properties. Such properties hang on the fragment of the tissue reflected and the class of the theme exposed along with the display conditions. These safety health standards fix limits connected to the effects of exposure to EMF accounting for the mentioned parameters. Regarding the emitted EMF, typically the mainly involved devices are those exerting significant stray fields as wireless energy and signal transmission devices. These implicate wide spreads of power and frequency. Two important categories are involved: digital communication and wireless power transfer. The circumstances of telecommunications involve ordinary EMF sources—for instance, radiofrequency (RF) waves emitted by antennas, Wi-Fi points, smartphones, mobile phones and Bluetooth tools. As the expended frequencies are high, and the exposed item regards the body tissues, controlling their safety conditions is necessary; see, e.g., [4][5][6][7][8][9][4,5,6,7,8,9]. In the case of wireless charging systems, applications vary from small devices such as telephone sets to high-powered devices, such as electric vehicles (EV). Various works have been carried out concerning the analysis of safety in the case of low power; see, e.g., [10][11][12][13][10,11,12,13]. High power tools such as those discussed in [14][15][16][17][18][19][20][14,15,16,17,18,19,20] present solid nearby EMF and can yield large fields in the body tissues, and we must identify the situations in which the charging scheme can conform to security; see, e.g., [21][22][23][24][25][26][21,22,23,24,25,26]. Note that the effects of exposure to EMF are different in these two application categories. In that of wireless communication tools (WCT), the field asset is relatively modest, but the exploited frequency is great, and the part of the body exposed is mainly the head area. In such circumstance, the most important biological effect (BE) is concentrated on the brain. In the situation of wireless inductive power transfer (IPT), as in EV battery-charging systems, the field intensity may be strong and display high leakage; the frequency is small; and the exposure regards bodies near the device. In these conditions, BE concerns the initiation of EMFs in the body.
Concerning disturbances in the operation of medical devices, these are generally shielded against external fields to avoid disturbing the on-board electronics. Nevertheless, in the case of devices whose operation is based on electromagnetic fields that could be disturbed by external fields or objects involved in medical instruments near or inside the device, typical examples are static fixed-function wearable measuring tools—e.g., [27][28][29][27,28,29]—active organ stimulation tools—e.g., [30][31][30,31]—and magnetic resonance imagers (MRI) used in image-guided therapies and interventions. Actually, these image-guided operations can use several types of imagers, e.g., [32][33][34][35][36][37][38][32,33,34,35,36,37,38]. Among these imagers, only two are free of ionizing radiation: the MRI and ultrasound imager (USI) [34][35][36][37][38][34,35,36,37,38]. However, the USI can only work without air or bones. The MRI seems to be the best solution, but as mentioned before, it is subject to perturbation by external EMF or objects involved in medical instruments near or inside the imager. To control the integrity of the MRI, an analysis of electromagnetic compatibility (EMC) is needed [39][40][41][42][43][44][45][39,40,41,42,43,44,45]. In general, in all of the above-mentioned medical devices that are subject to disturbance by EMF, an EMC control is necessary to verify the integrity of the medical device against the external field.
In both the above-described situations of biological tissues and medical devices, the most effective means for verification of the external field effect seem to be numerical tools based on mathematical modeling of the equations involved. The subject modeled can be the tissue of the body part (represented by an equivalent phantom) or the structure of the part of the medical device concerned.
The methodology followed in this contribution concerns mainly such verification of external field effects. In both cases of tissues and devices, the electromagnetic model facilitates the estimates of local distributed fields allowing the verification of the field thresholds relative to the tissues as well as the EMC analysis in the devices. Moreover, in the case of tissues, the bio-thermal model connected to the electromagnetic model allows the calculation of the temperature rise to verify the thermal threshold in the tissues.
This contribution aims to analyze compliance with the standards relating to health domain troubles due to exposure to electromagnetic fields (EMF). This concerns the exposed living tissues of the body and the interaction with medical devices acting on the body.

2. EMF Exposure

In different situations, EMFs are consumed every day in several sociable purposes. Additionally, they are employed securely in medical treatments. Conversely, when these fields are operated inadvertently, it can crop unfavorable outcomes. These consequences are intimately linked to the type of the EMF and the exposed substance. The strength of the field as well as its frequency typify EMF, whereas the physical and geometric properties describe matter.

2.1. Nature of EMF Sources

Essentially, the outcomes due to EMF exposure can be split into two different groups regarding the frequency ranges. One comprises the range of 103–1014 Hz for which waves can be divided into radio, microwaves and infrared that return non-ionizing radiation. The other interests the range of 1015–1022 Hz divided into ultraviolet, X and gamma rays, which create ionizing radiation. It is likely in this case to have hostile health effects by creating tissue damage. EMFs of diverse frequencies, in the scale of non-ionizing class, function in numerous situations and still can disorder society. In general, the emitting tools most involved in EMF non-ionizing exposure are, as mentioned before, those exercising noteworthy escaped fields such as wireless energy appliances including wide strength and frequency ranges. Two typical classes of such devices are WCT and IPT apparatuses. The case of WCT includes regular sources of RF, 105–3. 1011 Hz, while the case of IPT uses relatively low frequencies (less than 200 kHz).

2.2. Interactions of Sources and Living Tissues

In general, EMF sources can be divided into two classes: those working close to body tissues, producing an interacting near field greatly confined in a tissue portion of the body, and sources happening far away from the body that generate a total-body homogenous exposure. Roughly, far field relates to source-recipient distance superior to a wavelength, and its forte reduces quickly through distance. Interaction of the field with body tissues is influenced by the frequency, the field strength, the exposure time and the dielectric properties of absorbing matters. The character of interactions can produce effects due to short- or long-term exposure.
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