Complex Electromagnetic Issues Associated with the Use of Electric Vehicles in Urban Transportation.

The electromagnetic field (EMF) in electric vehicles (EVs) affects not only drivers, but also passengers (using EVs daily) and electronic devices inside. This article summarizes the measurement methods applicable in studies of complex EMF in EVs focused on the evaluation of characteristics of such exposure to EVs users and drivers, together with the results of investigations into the static magnetic field (SMF), the extremely low-frequency magnetic field (ELF) and radiofrequency (RF) EMF related to the use of the EVs in urban transportation. The investigated EMF components comply separately with limits provided by international labor law and guidelines regarding the evaluation of human short-term exposure; however other issues need attention-electromagnetic immunity of electronic devices and long-term human exposure. The strongest EMF was found in the vicinity of direct current (DC) charging installations-SMF up to 0.2 mT and ELF magnetic field up to 100 µT-and inside the EVs-up to 30 µT close to its internal electrical equipment. Exposure to RF EMF inside the EVs (up to a few V/m) was found and recognized to be emitted from outdoor radiocommunications systems, together with emissions from sources used inside vehicles, such as passenger mobile communication handsets and antennas of Wi-Fi routers.

Modelling and Evaluation of the Absorption of the 866 MHz Electromagnetic Field in Humans Exposed near to Fixed I-RFID Readers Used in Medical RTLS or to Monitor PPE.

The aim of this study was to model and evaluate the Specific Energy Absorption Rate (SAR) values in humans in proximity to fixed multi-antenna I-RFID readers of passive tags under various scenarios mimicking exposure when they are incorporated in Real-Time Location Systems (RTLS), or used to monitor Personal Protective Equipment (PPE). The sources of the electromagnetic field (EMF) in the modelled readers were rectangular microstrip antennas at a resonance frequency in free space of 866 MHz from the ultra-high frequency (UHF) RFID frequency range of 865-868 MHz. The obtained results of numerical modelling showed that the SAR values in the body 5 cm away from the UHF RFID readers need consideration with respect to exposure limits set by international guidelines to prevent adverse thermal effects of exposure to EMF: when the effective radiated power exceeds 5.5 W with respect to the general public/unrestricted environments exposure limits, and with respect to occupational/restricted environments exposure limits, when the effective radiated power exceeds 27.5 W.

Modelling the Influence of Electromagnetic Field on the User of a Wearable IoT Device Used in a WSN for Monitoring and Reducing Hazards in the Work Environment.

The aim of this study was to evaluate the absorption in a user's head of an electromagnetic field (EMF) emitted by the Wi-Fi and/or Bluetooth module of a wearable small Internet of Things (IoT) electronic device (emitting EMF of up to 100 mW), in order to test the hypothesis that EMF has an insignificant influence on humans, and to compare the levels of such EMF absorption in various scenarios when using this device. The modelled EMF source was a meandered inverted-F antenna (MIFA)-type antenna of the ESP32-WROOM-32 radio module used in wearable devices developed within the reported study. To quantify the EMF absorption, the specific energy absorption rate (SAR) values were calculated in a multi-layer ellipsoidal model of the human head (involving skin, fat, skull bones and brain layers). The obtained results show up to 10 times higher values of SAR from the MIFA located in the headband, in comparison to its location on the helmet. Only wearable IoT devices (similar in construction and way of use to the investigated device) emitting at below 3 mW equivalent isotropically radiated power (EIRP) from Wi-Fi/Bluetooth communications modules may be considered environmentally insignificant EMF sources.

Evaluation of the Influence of Magnetic Field on Female Users of an Induction Hob in Ergonomically Sound Exposure Situations.

The hypothesis being tested was that the exposure of female workers to the electromagnetic field (EMF) emitted by an induction hob (IHb) meeting public exposure limitations (evaluated according to EN/IEC 62233) is also compliant with European Directive 2013/35/EU on workers' protection. The electric field induced in three female models in a realistic ergonomically comfortable posture near IHb was evaluated using numerical models of 25 kHz EMF sources (IHb covered by cooking vessels). It was found that, in analyzed ergonomically comfortable exposure situations, the electric field induced in the user's body may exceed public and workers' limits when the vessels do not match the dimensions of IHb's heating zone. This can even be the case when IHb complies with Conformité Européenne labeling requirements (i.e. EMF exposure falls below public limits 30 cm away from IHb edge). In the 36 exposure scenarios analyzed, statistically significant differences were found when the distances from IHb and vessel dimension, and the height and body mass index of models in exposure scenarios varied, but not between the use of models of pregnant and nonpregnant women. The use of IHb complying with European requirements on general public protection does not ensure that EMF exposure to workers complies with the relevant limits. Adequate protection measures need to address these occupational environmental hazards. © 2020 Bioelectromagnetics Society.

Electromagnetic Energy Absorption in a Head Approaching a Radiofrequency Identification (RFID) Reader Operating at 13.56 MHz in Users of Hearing Implants Versus Non-Users.

The aim of this study was to model the absorption in the head of an electromagnetic field (EMF) emitted by a radiofrequency identification reader operating at a frequency of 13.56 MHz (recognized as an RFID HF reader), with respect to the direct biophysical effects evaluated by the specific absorption rate (SAR), averaged over the entire head or locally, over any 10 g of tissues. The exposure effects were compared between the head of a user of a hearing implant with an acoustic sensor and a person without such an implant, used as a referenced case. The RFID HF reader, such as is used in shops or libraries, was modeled as a loop antenna (35 × 35 cm). SAR was calculated in a multi-layer ellipsoidal model of the head-with or without models of hearing implants of two types: Bonebridge (MED-EL, Austria) or bone anchored hearing aid attract (BAHA) (Cochlear, Sweden). Relative SAR values were calculated as the ratio between the SAR in the head of the implant user and the non-user. It was found that the use of BAHA hearing implants increased the effects of 13.56 MHz EMF exposure in the head in comparison to non-user-up to 2.1 times higher localized SAR in the worst case exposure scenario, and it is statistically significant higher than when Bonebridge implants are used (Kruscal-Wallis test with Bonferroni correction, p < 0.017). The evaluation of EMF exposure from an RFID reader with respect to limits established for the implant non-user population may be insufficient to protect an implant user when exposure approaches these limits, but the significant difference between exposure effects in users of various types of implants need to be considered.

An Evaluation of Electromagnetic Exposure While Using Ultra-High Frequency Radiofrequency Identification (UHF RFID) Guns.

The aim is to evaluate specific absorption rate (SAR) values from exposure near handheld ultra-high frequency radiofrequency identification readers (UHF RFID guns-small electronic devices, or even portable computers with relevant accessories-emitting up to several watts of electromagnetic field (EMF) to search for RFID sensors (tags) attached to marked objects), in order to test the hypothesis that they have an insignificant environmental influence. Simulations of SAR in adult male and female models in seven exposure scenarios (gun near the head, arm, chest, hip/thigh of the operator searching for tags, or near to the chest and arm of the scanned person or a bystander). The results showed EMF exposure compliant with SAR limits for general public exposure (ICNIRP/European Recommendation 1999/519/EC) at emissions up to 1 W (reading range 3.5-11 m, depending on tag sensitivity). In the worst-case scenario, guns with a reading range exceeding 5 m (>2 W emission) may cause an SAR exceeding the general public limits in the palm of the user and the torso of the user, a bystander, or a scanned person; occupational exposure limits may be exceeded when emission >5 W. Users of electronic medical implants and pregnant women should be treated as individuals at particular risk in close proximity to guns, even at emissions of 1 W. Only UHF RFID guns emitting below 1 W may be considered as environmentally insignificant EMF sources.

Evaluation of the safety of users of active implantable medical devices (AIMD) in the working environment in terms of exposure to electromagnetic fields - Practical approach to the requirements of European Directive 2013/35/EU.

OBJECTIVES: Electromagnetic fields (EMF) may cause malfunctions in electronic devices, in particular in active implantable medical devices (AIMD), along with discomfort or health hazards to users. The use of AIMD by workers is increasing (especially cardiac pacemakers, implantable cardioverter defibrillators and wearable insulin infusion pumps). Electromagnetic fields may be much stronger in the working environment than applied in basic immunity tests of AIMD (based on EN 60601- 1-2:2015 and EN 50527-1:2016). European Directive 2013/35/EU regarding the safety of workers exposed to EMF considered the AIMD users to be "workers at particular risk" who need an individual evaluation of EMF hazards. The study aimed at evaluating the safety of users of AIMD in medical and industrial working environments exposed to EMF. MATERIAL AND METHODS: Near the common sources of strong EMF applied in medical and industrial use, the "standard safety distances" (SSD) for AIMD users were evaluated (i.e., distances from the EMF source, where exposure drops below limits from Recommendation 1999/519/EC and AIMD safety may be expected). The analysis is based on the results of measurements of magnetic and electric field strengths near 127 typical devices, in their normal use. RESULTS: The longest electric field related SSD was identified near dielectric sealers (up to 180 cm), and the longest magnetic field related SSD - near induction heaters (up to 450 cm). CONCLUSIONS: Electromagnetic fields related AIMD malfunctions need to be considered up to several meters from EMF sources. The "individual safety distance," that is sufficient to ensure the safety of a particular AIMD user may be significantly different (usually shorter) from the presented SSD, but needs to be considered in the context of detailed safety data from the AIMD manufacturer (if available). The labelling indicating the location of the area of a strong EMF increases safety of AIMD users in the work environment. Int J Occup Med Environ Health 2018;31(6):795-808.

In silico modelling of influence from low or intermediate frequency magnetic fields on users of wearable insulin pumps.

PURPOSE: The aim was to model the effects of exposure to a low or intermediate frequency electromagnetic field (LIF-EMF), characterized by the electric field induced in the body, in order to evaluate how the type of insulin needle and the way it is injected influences the exposed user of a wearable insulin pump. MATERIAL AND METHODS: Numerical models of exposure scenarios (sources of LIF-EMF, with a dominant magnetic component: 50Hz-1MHz; the insulin needle type; the way it is injected and insulin pump user) were worked out. The influence of the insulin needle on the user's safety (the ratio of the induced electric field in tissues surrounding the needle and tissues of a person without an injection, both exposed identically) were calculated. RESULTS: The effects of LIF-EMF exposure in insulin pump users were found to be up to approximately 7-times higher, varying with statistically significance (p < .05) with the material of the needle, the way it is injected and the polarization of the affecting magnetic field. CONCLUSIONS: When steel insulin needles is used, the assessment of user's EMF exposure should be carried out using magnetic field limits at least 5-times lower than given in general international requirements.

An In Situ and In Silico Evaluation of Biophysical Effects of 27 MHz Electromagnetic Whole Body Humans Exposure Expressed by the Limb Current.

OBJECTIVES: The aim was to evaluate correlations between biophysical effects of 27 MHz electromagnetic field exposure in humans (limb induced current (LIC)) and (1) parameters of affecting heterogeneous electric field and (2) body anthropometric properties, in order to improve the evaluation of electromagnetic environmental hazards. METHODS: Biophysical effects of exposure were studied in situ by measurements of LIC in 24 volunteers (at the ankle) standing near radio communication rod antenna and in silico in 4 numerical body phantoms exposed near a model of antenna. RESULTS: Strong, positive, statistically significant correlations were found in all exposure scenarios between LIC and body volume index (body height multiplied by mass) (r > 0.7; p < 0.001). The most informative exposure parameters, with respect to the evaluation of electromagnetic hazards by measurements (i.e., the ones strongest correlated with LIC), were found to be the value of electric field (unperturbed field, in the absence of body) in front of the chest (50 cm from body axis) or the maximum value in space occupied by human. Such parameters were not analysed in previous studies. CONCLUSIONS: Exposed person's body volume and electric field strength in front of the chest determine LIC in studied exposure scenarios, but their wider applicability needs further studies.

[Evaluation of hazards caused by magnetic field emitted from magnetotherapy applicator to the users of bone conduction hearing prostheses]. / Ocena zagrozen wynikajacych z oddzialywania pola magnetycznego emitowanego przez aplikator magnetoterapeutyczny dla uzytkowników protez sluchu wykorzystujacych przewodnictwo kostne.

BACKGROUND: Low frequency magnetic field, inducing electrical field (Ein) inside conductive structures may directly affect the human body, e.g., by electrostimulation in the nervous system. In addition, the spatial distribution and level of Ein are disturbed in tissues neighbouring the medical implant. MATERIAL AND METHODS: Numerical models of magneto-therapeutic applicator (emitting sinusoidal magnetic field of frequency 100 Hz) and the user of hearing implant (based on bone conduction: Bonebridge type - IS-BB or BAHA (bone anchorde hearing aid) type - IS-BAHA) were worked out. Values of Ein were analyzed in the model of the implant user's head, e.g., physiotherapist, placed next to the applicator. RESULTS: It was demonstrated that the use of IS-BB or IS-BAHA makes electromagnetic hazards significantly higher (up to 4-fold) compared to the person without implant exposed to magnetic field heterogeneous in space. Hazards for IS-BAHA users are higher than those for IS-BB users. It was found that applying the principles of directive 2013/35/EU, at exposure to magnetic field below exposure limits the direct biophysical effects of exposure in hearing prosthesis users may exceed relevant limits. Whereas applying principles and limits set up by Polish labor law or the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines, the compliance with the exposure limits also ensures the compliance with relevant limits of electric field induced in the body of hearing implant user. CONCLUSIONS: It is necessary to assess individually electromagnetic hazard concerning hearing implant users bearing in mind significantly higher hazards to them compared to person without implant or differences between levels of hazards faced by users of implants of various structural or technological solutions. Med Pr 2017;68(4):469-477.

Evaluation of exposure to (ultra) high static magnetic fields during activities around human MRI scanners.

OBJECTIVE: To assess the individual exposure to the static magnetic field (SMF) and the motion-induced time-varying magnetic field (TVMF) generated by activities in an inhomogeneous SMF near high and ultra-high field magnetic resonance imaging (MRI) scanners. The study provides information on the level of exposure to high and ultra-high field MRI scanners during research activities. MATERIALS AND METHODS: A three-axis Hall magnetometer was used to determine the SMF and TVMF around human 3- and 7-Tesla (T) MRI systems. The 7-T MRI scanner used in this study was passively shielded and the 3-T scanner was actively shielded and both were from the same manufacturer. The results were compared with the exposure restrictions given by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). RESULTS: The recorded exposure was highly variable between individuals, although they followed the same instructions for moving near the scanners. Maximum exposure values of B = 2057 mT and dB/dt = 4347 mT/s for the 3-T scanner and B = 2890 mT, dB/dt = 3900 mT/s for 7 T were recorded. No correlation was found between reporting the MRI-related sensory effects and exceeding the reference values. CONCLUSIONS: According to the results of our single-center study with five subjects, violation of the ICNIRP restrictions for max B in MRI research environments was quite unlikely at 3 and 7 T. Occasions of exceeding the dB/dt limit at 3 and 7 T were almost similar (30% of 60 exposure scenarios) and highly variable among the individuals.

Radiofrequency electromagnetic radiation exposure inside the metro tube infrastructure in Warszawa.

Antennas from various wireless communications systems [e.g. mobile phones base transceiver stations (BTS) and handsets used by passengers, public Internet access, staff radiophone transmitters used between engine-drivers and traffic operators] emitting radiofrequency electromagnetic radiation (RF-EMR) are used inside underground metro public transportation. Frequency-selective exposimetric investigations of RF-EMR exposure inside the metro infrastructure in Warsaw (inside metro cars passing between stations and on platforms) were performed. The statistical parameters of exposure to the E-field were analyzed for each frequency range and for a total value (representing the wide-band result of measurements of complex exposure). The recorded exposimetric profiles showed the dominant RF-EMR sources: handsets and BTS of mobile communication systems (GSM 900 and UMTS 2100) and local wireless Internet access (WiFi 2G). Investigations showed that the GSM 900 system is the dominant source of exposure - BTS (incessantly active) on platforms, and handsets - used by passengers present nearby during the tube drive. The recorded E-field varies between sources (for BTS were: medians - 0.22 V/m and 75th percentile - 0.37 V/m; and for handsets: medians - 0.28 V/m and 75th percentile - 0.47 V/m). Maximum levels (peaks) of exposure recorded from mobile handsets exceeded 10 V/m (upper limit of used exposimeters). Broadband measurements of E-field, including the dominant signal emitted by staff radiophones (151 MHz), showed that the level of this exposure of engine-drivers does not exceed 2.5 V/m.

The role of the location of personal exposimeters on the human body in their use for assessing exposure to the electromagnetic field in the radiofrequency range 98-2450 MHz and compliance analysis: evaluation by virtual measurements.

The use of radiofrequency (98-2450 MHz range) personal exposimeters to measure the electric field (E-field) in far-field exposure conditions was modelled numerically using human body model Gustav and finite integration technique software. Calculations with 256 models of exposure scenarios show that the human body has a significant influence on the results of measurements using a single body-worn exposimeter in various locations near the body ((from -96 to +133)%, measurement errors with respect to the unperturbed E-field value). When an exposure assessment involves the exposure limitations provided for the strength of an unperturbed E-field. To improve the application of exposimeters in compliance tests, such discrepancies in the results of measurements by a body-worn exposimeter may be compensated by using of a correction factor applied to the measurement results or alternatively to the exposure limit values. The location of a single exposimeter on the waist to the back side of the human body or on the front of the chest reduces the range of exposure assessments uncertainty (covering various exposure conditions). However, still the uncertainty of exposure assessments using a single exposimeter remains significantly higher than the assessment of the unperturbed E-field using spot measurements.

Evaluation of exposure to electromagnetic radiofrequency radiation in the indoor workplace accessible to the public by the use of frequency-selective exposimeters.

OBJECTIVES: The aim of the study was to identify and assess electromagnetic radiofrequency radiation (EMRR) exposure in a workplace located in a publicly accessible environment, and represented by offices (where exposure is caused by various transmitters of local fixed indoor and outdoor wireless communication systems). MATERIAL AND METHODS: The investigations were performed in 45 buildings (in urban and rural areas in various regions of Poland), using frequency-selective electric field strength (E-field) exposimeters sensitive to the EMRR with a frequency range of 88-2500 MHz, split into 12 sub-bands corresponding to the operating frequencies of typical EMRR sources. The variability of the E-field was analyzed for each frequency range and the total level of exposure by statistical parameters of recorded exposimetric profiles: minimum, maximum, median values and 25-75th - percentiles. RESULTS: The main sources of exposure to EMRR are mobile phone base transceiver stations (BTS) and radio-television transmitters (RTV). The frequency composition in a particular office depends on the building's location. The E-field recorded in buildings in urban and rural areas from the outdoor BTS did not exceed respectively: medians - 0.19 and 0.05 V/m, 75th percentiles -0.25 and 0.09 V/m. In buildings equipped with the indoor BTS antennas the E-field did not exceed: medians - 1 V/m, 75th percentiles - 1.8 V/m. Whereas in urban and rural areas, the median and 75th percentile values of the E-field recorded in buildings located near the RTV (within 1 km) did not exceed: 1.5 and 3.8 V/m or 0.4 and 0.8 V/m, for radio FM band or for TV bands, respectively. CONCLUSIONS: Investigations confirmed the practical applicability of the exposimetric measurements technique for evaluating parameters of worker's exposure in both frequency- and time-domain. The presented results show EMRR exposure of workers or general public in locations comparable to offices to be well below international limits.

[Anthropometric differentiation of effects of radiofrequency electromagnetic fields of frequency 100 MHz on workers]. / Antropometryczne zróznicowanie oddzialywania na pracownika radiofalowych pól elektromagnetycznych o czestotliwosciach 100 MHz.

BACKGROUND: Thermal effects of radiofrequency electromagnetic fields (REMF) exposure of humans may be assessed by calculations of the parameter recognized as SAR (specific energy absorption rate) in virtual human body models, which actually do not represent anthropometric properties of the entire population. Therefore, it is important to determine the relations between SAR values and anthropometric parameters that enable individualization of SAR estimation independently of body properties of a given person. MATERIAL AND METHODS: The analysis concerned 48 exposure scenarios of 4 virtual body models (male and female) to vertically or horizontally polarized REMF of 27 MHz or 100 MHz frequency of various directions of propagation. RESULTS: In the subgroup of results 100 MHz/vertical polarization statistically significant (strong; p < 0.05) correlations were identified between SAR averaged in the whole body and height, mass, BMI, circumference of chest, waist, neck and frontal cross-section area, and between local SAR in head and neck and the height, mass, circumference of chest waist or neck and frontal cross-section area. Identified relations and SAR in the Gustav model were used to estimate the variety of SAR in Polish population of adults (5-95. percentile of female and male): +/- 30% for SAR averaged in the whole body, +/- 50% for localized SAR. CONCLUSIONS: It was demonstrated that in the preliminary classified type of assessed REMF exposure (e.g., in terms of field polarization and frequency) it is possible to identify statistical relations between various SAR parameters and anthropometric properties of the exposed body. Related quantities can be used for individualized assessment of worker's electromagnetic hazards.

Environmental impact of the use of radiofrequency electromagnetic fields in physiotherapeutic treatment.

BACKGROUND: Electromagnetic fields used in physiotherapeutic treatment affect not only patients, but also physiotherapists, patients not undergoing treatment and electronic medical equipment. OBJECTIVE: The aim of the work was to study the parameters of the electromagnetic fields of physiotherapeutic devices with respect to requirements regarding the protection of electronic devices, including medical implants, against electromagnetic intererence, and the protection of the general public (patients not undergoing treatment and bystanders), as well as medical personnel, against the health hazards caused by electromagnetic exposure. MATERIAL AND METHODS: The spatial distribution of electric and magnetic field strength was investigated near 3 capacitive short-wave and 3 long-wave diathermies and 3 ultrasound therapy units, as along with the capacitive electric currents caused by electromagnetic field interaction in the upper limbs of the physiotherapists operating these devices. RESULTS: The physiotherapists' exposure to electromagnetic fields depends on the spatial organisation of the workspace and their location during treatment. Electric fields able to interfere with the function of electronic medical implants and in whic anyone not undergoing treatment should not be present were measured up to 150-200 cm away from active applicators of short-wave diathermy, and up to 40-45 cm away from long-wave diathermy ones. Electric fields in which workers should not be present were measured up to 30-40 cm away from the applicators and cables of active short-wave diathermy devices. A capacitive electric current with a strength exceeding many times the international recommendations regarding workers protection was measured in the wrist while touching applicators and cables of active short-wave diathermy devices. CONCLUSIONS: The strongest environmental electromagnetic hazards occur near short-wave diathermy devices, and to a lesser degree near long-wave diathermy devices, but were not found near ultrasound therapy units.

An assessment of hazards caused by electromagnetic interaction on humans present near short-wave physiotherapeutic devices of various types including hazards for users of electronic active implantable medical devices (AIMD).

Leakage of electromagnetic fields (EMF) from short-wave radiofrequency physiotherapeutic diathermies (SWDs) may cause health and safety hazards affecting unintentionally exposed workers (W) or general public (GP) members (assisting patient exposed during treatment or presenting there for other reasons). Increasing use of electronic active implantable medical devices (AIMDs), by patients, attendants, and workers, needs attention because dysfunctions of these devices may be caused by electromagnetic interactions. EMF emitted by 12 SWDs (with capacitive or inductive applicators) were assessed following international guidelines on protection against EMF exposure (International Commission on Nonionizing Radiation Protection for GP and W, new European directive 2013/35/EU for W, European Recommendation for GP, and European Standard EN 50527-1 for AIMD users). Direct EMF hazards for humans near inductive applicators were identified at a distance not exceeding 45 cm for W or 62 cm for GP, but for AIMD users up to 90 cm (twice longer than that for W and 50% longer than that for GP because EMF is pulsed modulated). Near capacitive applicators emitting continuous wave, the corresponding distances were: 120 cm for W or 150 cm for both-GP or AIMD users. This assessment does not cover patients who undergo SWD treatment (but it is usually recommended for AIMD users to be careful with EMF treatment).

Experimental evaluation of ballistic hazards in imaging diagnostic center.

BACKGROUND: Serious hazards for human health and life and devices in close proximity to the magnetic resonance scanners (MRI scanners) include the effects of being hit by ferromagnetic objects attracted by static magnetic field (SMF) produced by scanner magnet - the so-called ballistic hazards classified among indirect electromagnetic hazards. International safety guidelines and technical literature specify different SMF threshold values regarding ballistic hazards - e.g. 3 mT (directive 2004/40/EC, EN 60601-2-33), and 30 mT (BMAS 2009, directive proposal 2011). Investigations presented in this article were performed in order to experimentally verify SMF threshold for ballistic hazards near MRI scanners used in Poland. MATERIAL/METHODS: Investigations were performed with the use of a laboratory source of SMF (0-30 mT) and MRI scanners of various types. The levels of SMF in which metal objects of various shapes and 0.4-500 g mass are moved by the field influence were investigated. The distance from the MRI scanners (0.2-3T) where hazards may occur were also investigated. RESULTS: Objects investigated under laboratory conditions were moved by SMF of 2.2-15 mT magnetic flux density when they were freely suspended, but were moved by the SMF of 5.6-22 mT when they were placed on a smooth surface. Investigated objects were moved in fields of 3.5-40 mT by MRI scanners. Distances from scanner magnet cover, where ballistic hazards might occur are: up to 0.5 m for 0.2-0.3T scanners; up to 1.3 m for 0.5T scanners; up to 2.0 m for 1.5T scanners and up to 2.5 m for 3T scanners (at the front and back of the magnet). CONCLUSIONS: It was shown that SMF of 3 mT magnetic flux density should be taken as the threshold for ballistic hazards. Such level is compatible with SMF limit value regarding occupational safety and health-protected areas/zones, where according to the Polish labor law the procedures of work environment inspection and prevention measures regarding indirect electromagnetic hazards should be applied. Presented results do not support the increase up to 30 mT of the SMF limit for protected area.

The pattern of exposure to static magnetic field of nurses involved in activities related to contrast administration into patients diagnosed in 1.5 T MRI scanners.

Static magnetic fields (SMFs) and time-varying electromagnetic fields exposure is necessary to obtain the diagnostic information regarding the structure of patient's tissues, by the use of magnetic resonance imaging (MRI) scanners. A diagnostic procedure may also include the administration of pharmaceuticals called contrast, which are to be applied to a patient during the examination. The nurses involved in administering contrast into a patient during the pause in examination are approaching permanently active magnets of MRI scanners and are exposed to SMF. There were performed measurements of spatial distribution of SMF in the vicinity of MRI magnets and parameters of personal exposure of nurses (i.e. individual exposimetric profiles of variability in time of SMF affecting the nurse who is performing tasks in the vicinity of magnet, characterized by statistical parameters of recorded magnetic flux density affecting the nurse). The SMF exposure in the vicinity of various MRI magnets depends on both magnetic flux density of the main field B 0 (applicable to a patient) and the construction of the scanner, but the most important factor determining the workers' exposure is the work practice. In the course of a patient's routine examination in scanners of B0 = 1.5 T, the nurses are present over ∼0.4-2.9 min in SMF exceeding 0.03% of B0 (i.e. 0.5 mT), but only sometimes they are present in SMF exceeding 5% of B 0 (i.e. 75 mT). When patients need more attention because of their health status/condition, the nurses' exposure may be significantly longer--it may even exceed 10 min and 30% of B 0 (i.e. 500 mT). We have found that the level of exposure of nurses to SMF may vary from < 5% of the main field (a median value: 0.5-1.5%; inter-quartile range: 0.04-8.8%; max value: 1.3-12% of B0) when a patient is moved from the magnets bore before contrast administration, up to the main field level (B0) when a patient stays in the magnets bore and nurse is crawling into the bore.

[Objectivized evaluation of surgeons exposure to radiofrequency electromagnetic fields -- in the context of exposure duration and Polish and new international requirements regarding workers protection]. / Zobiektywizowana ocena narazenia chirurgów na radiofalowe pola elektromagnetyczne - w kontekscie czasu narazenia oraz Polskich i znowelizowanych miidzynarodowych wymagai dotyczicych ochrony pracowników.

BACKGROUND: Use of electro surgery units (ESU) in surgeries is linked with electromagnetic field emission, which is assessed according to the requirements of occupational health and safety legislation. MATERIAL AND METHODS: Surgeons' exposure characteristics was monitored during 11 surgeries (proctectomy, patency of artery, hepatectomy, cystectomy, tonsilectomy, laparoscopy) by real time of monopolar ESU activity recorder. Investigations of root-mean-square value of electric and magnetic field strength was also performed at various modes of ESU operations during cutting (output power, 55-150 W; frequency, 330-445 kHz) and coagulating (40-240 W, 335-770 kHz). Statistical parameters of distribution of ESU operation over any 6-min periods (according to international requirements regarding protection against adverse thermal effects of electromagnetic field) were assessed. RESULTS: Electric field strength, measured 10 cm from the cable supplying an active electrode was 147-675 V/m during cutting and 297-558 V/m during coagulating; magnetic field strength was less than 0.2 A/m in both modes. Monitoring of ESUs showed the following ranges of their operation during surgeries 5-66% of time over starting 3 min of surgery, 3-40% over starting 6 min, and the distribution of their use over any 6-min periods 0-12% (median) / 7-43% (maximum value). CONCLUSIONS: The real operation time of ESUs ing surgeries was significantly shorter than that declared by workers. The distance of at least 15 cm between cables, connecting electrodes with generator and workers meets the requirements of the Polish legislation on permissible exposure limits. The assessment of localized exposure of the hand needs a detailed analysis of the SAR ratio distribution and further studies are required.