Articles

 

ARTICLES

 

 

  1. Karpowicz J., Miguel-Bilbao S., Ramos V., Falcone F., Gryz K., Leszko W., Zradziński P., The evaluation of Stationary and Mobile Components of Radiofrequency Electromagnetic Exposure in the Public Accessible Environment. EMC Europe 2017, Angers, Francja, 04-08.09.2017 r., IEEE Xplore (4 str.), DOI: 10.1109/EMCEurope.2017.8094751
    Abstract
    Frequency-selective exposimeters were used to evaluate stationary and mobile components of exposure to radiofrequency electromagnetic radiation in the public accessible environment, with respect to the location in the urban area and intensity of mobile communication traffic. It was found that in the crowded public space the uplink mobile component of exposure and wide-band internet access may be at least so strong as the exposure from stationary radiofrequency emitters. It needs attention in the context of safety of vulnerable population, such as medical implants or tele-medicine users, because it may cause local hot spots of overexposure with respect to the limit of radiofrequency exposure, which may influence function of medical electronic devices.

  2. Miguel-Bilbao S., Karpowicz J., Febles V., Hernández J. A., Suárez S., Ramos V., Leszko W., Gryz K., Electromagnetic Exposure Hot-spots in a Healthcare Environment, Caused by Smart Metering to Control Public Utilities. The 6th IEEE International Conference on E-Health and Bioengineering - EHB 2017 Sinaia, Rumunia, 22-24.06.2017 r.; IEEE Xplore (4 str), DOI: 10.1109/EHB.2017.7995496
    Abstract
    Smart metering systems using the wireless transfer of data to control the consumption of various public utilities are among the sources of localised electromagnetic exposure in a healthcare environment. The environmental health and safety impact of this technology is under public concern. Our study focuses on the international evaluation of parameters characterising localised hot-spot exposure near smart meter facilities used in various healthcare environments. Significant differences in the exposure characteristics were found between locations. Localised electromagnetic field exposure at levels that may cause electromagnetic hazards in the specific healthcare environment have been found near smart metering facilities (in the range of several dozen centimetres). It needs attention and further wider studies.

  3. P. Zradziński,A Comparison of ICNIRP and IEEE Guidelines to Evaluate Low Frequency Magnetic Field Localised Exposure. Proc. of the 2016 17th International Conference on Computational Problems of Electrical Engineering (CPEE), Sandomierz, Poland, September 14-17, 2016, pp. 668-671, IEEE Xplore Digital Library (4 str.), DOI: 10.1109/CPEE.2016.7738764 
    Abstract
    Numerical calculations of exposure to magnetic field of operators of suspended hand-operated resistance welding guns were performed using the own homogeneous, flexible human body models CIOP-MAN of the 95th and 5th percentile of adult men dimensions (185 and 164 cm in height), in 16 exposure situations with various postures of operator - typical for automotive factory. An assessment concerned calculated values of an induced electric field (Ein) in the brain and the heart - according to the ICNIRP (International Commission on Non-Ionizing Radiation Protection, 2010) and the IEEE (Institute of Electrical and Electronics Engineers, 2002). The results show applicability of flexible human body models in exposure evaluation based on Ein values, even homogeneous. The values of Ein in the brain and the heart are up to 34% higher when calculated following ICNIRP requirements than the values calculated following the IEEE method. The values of a welding current producing a B-field in the heart area of 100 μT/50Hz (i.e. the exposure limit for cardiac pacemakers users provided by ACGIH (American Conference of Governmental Industrial Hygienists, 2016) and CENELEC standard (European Committee for Electrotechnical Standardization)) are in the range of 0.43-1.6 kA, which is significantly lower than the typical current used in the industry (5-15 kA). Cardiac pacemaker users should not operate welding guns, as a result of the individual risk assessment required by the European directive on workers' protection (Directive 2013/35/EU).

  4. P. Zradziński, Difficulties in applying numerical simulations to an evaluation of occupational hazards caused by electromagnetic fields, International Journal of Occupational Safety and Ergonomics (JOSE), 2015, 21, 2: 213-220, DOI:10.1080/10803548.2015.1028233
    Abstract
    Due to the various physical mechanisms of interaction between a worker's body and the electromagnetic field at various frequencies, the principles of numerical simulations have been discussed for three areas of worker exposure: to low frequency magnetic field, to low and intermediate frequency electric field and to radiofrequency electromagnetic field. This paper presents the identified difficulties in applying numerical simulations to evaluate physical estimators of direct and indirect effects of exposure to electromagnetic fields at various frequencies. Exposure of workers operating a plastic sealer have been taken as an example scenario of electromagnetic field exposure at the workplace for discussion of those difficulties in applying numerical simulations. The following difficulties in reliable numerical simulations of workers' exposure to the electromagnetic field have been considered: workers' body models (posture, dimensions, shape and grounding conditions), working environment models (objects most influencing electromagnetic field distribution) and an analysis of parameters for which exposure limitations are specified in international guidelines and standards. n an exposure assessment for EMF-related epidemiological studies. The outcomes of the presented examination of virtual phantoms used in numerical simulations show that they can be effectively used in the assessment of compliance with the exposure limits specified by Directive 2013/35/EU, but various other factors should be also considered, e.g., the relationship between phantom posture and a realistic exposure situation (flexible phantoms use), limited resolution preventing reliable evaluation of physical estimators of exposure, or a non-realistic area of phantom surface in contact with the ground.

  5. P. Zradziński, The examination of virtual phantoms with respect to their involvement in a complance assessment against the limitations of electromagnetic hazards provided by European Directive 2013/35/EU, International Journal of Occupational Medicine and Environmental Health,  2015;28(5):781–792,  DOI:10.13075/ijomeh.1896.00342
    Abstract
    According to Directive 2013/35/EU, any assessment of hazards associated with exposure to electromagnetic fields (EMF) in the workplace needs an evaluation of quantities characterizing biophysical effects caused inside human bodies by exposure. Such quantities (induced electric field or specific energy absorption rate) may be evaluated by computer simulations in virtual models (phantoms), representing interaction between EMF and the worker's body with respect to modelling the EMF source, the structure of the working environment and the human body. The paper describes the effects of the properties of various virtual phantoms used in recently published studies on various aspects of EMF exposure with respect to their possible involvement in assessing occupational electromagnetic hazards as required by Directive 2013/35/ EU. The parameters of phantoms have been discussed with reference to: dimensions, posture, spatial resolution and electric contact with the ground. Such parameters should be considered and specified, and perhaps also standardized, in order to ensure that the numerical simulations yield reliable results in a compliance analysis against exposure limits or in an exposure assessment for EMF-related epidemiological studies. The outcomes of the presented examination of virtual phantoms used in numerical simulations show that they can be effectively used in the assessment of compliance with the exposure limits specified by Directive 2013/35/EU, but various other factors should be also considered, e.g., the relationship between phantom posture and a realistic exposure situation (flexible phantoms use), limited resolution preventing reliable evaluation of physical estimators of exposure, or a non-realistic area of phantom surface in contact with the ground.

  6. K. Gryz, P. Zradziński, J. Karpowicz, The role of the location of personal exposimeters on the human body in their use for assessing exposure to electromagnetic field in the radiofrequency range 98-2450 MHz and compliance analysis: evaluation by virtual measurements, BioMed Research International, 2015 online http://dx.doi.org/10.1155/2015/272460
    Abstract
    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.

  7. J. Karpowicz, K. Gryz, The practical application of limb contact current limits in the safety programme at electromagnetically exposed workplace – 2016 International Conference on Applied and Theoretical Electricity (ICATE), Book Series: International Conference on Applied and Theoretical Electricity – 2016 (5 str.) ‐ IEEE Xplore/Scopus/Web of Science; DOI: 10.1109/ICATE.2016.7754695
    Abstract
    The international guidelines (including European Directive 2013/35/EU) set out limits for limb contact currents in the frequency up to 110 MHz, in order to protect workers against the indirect effects of exposure to electromagnetic field. The aim of the study was to analyse the practical role of that kind of metric for an evaluation of the electromagnetic hazards at the workplace. For the practical application of limb contact current limits, the practical limitations need to be considered in their in-situ evaluation by measurements, such as the uncertainty of the level of contact current related hazards of at least +/-50% (covering inter-person variability, the influence of the contact and exposure conditions and the calibration of measurement devices). Additionally, with respect to bioethical rules, such an evaluation in routine occupational safety practice needs the use of phantoms (e.g. equivalent circuits) replacing the human body in the measurement circuits - which increases the uncertainty of the evaluation. The next important limitation is caused by inter-person variability in sensitivity to limb currents, which mean that some percentage of workers are sensitive to limb current flow at levels significantly lower than their relevant limits. Considering such practical problems, the management of contact current related hazards should be based on the implementation of sufficient protection measures where a high exposure level at the workplace is identified by electric or magnetic field measurements, avoiding individual tests of contact current levels.

  8. . Karpowicz, K. Gryz,  P. Zradzińsk, An Experimental Study on Limb Contact Current (Perception and Current Load) at an Electromagnetically‐exposed Workplace ‐ the study focused on intermediate‐and radio‐frequency exposure – International Conference on Applied and Theoretical Electricity (ICATE), Book Series: International Conference on Applied and Theoretical Electricity – 2016 (5 str.); IEEE Xplore/Scopus/Web of Science; DOI: 10.1109/ICATE.2016.7754696
    Abstract
    The limits for limb contact currents noted at the workplace exposed to electromagnetic fields with a frequency up to 110MHz have been set out by international guidelines (including European Directive 2013/35/EU) to protect workers against the indirect effects of exposure. The aim of this study was to analyse what level of limb currents exceed the perception threshold in the intermediate- and radio-frequency range used mostly by new telecommunication and power transfer technologies (f>15kHz). In tests with a group of healthy adult males, in the intermediate-/radio-frequency experiments, the contact current perception threshold was found to be proportional to the size of the contact area ((0.4-1.4)cm in diameter), and less inter-personally spread for larger contact areas, higher frequencies and for use of electro-conductive gel. Some percentage of workers are sensitive to limb current flow at levels significantly lower than the relevant limits. The tests, involving volunteers and the use of several clamp-on current meters, where focused on the in-situ evaluation of limb contact currents near broadcasting antennas. They showed that, in practice, the uncertainty of measurements reach +/-50%-covering inter-person variability, influence of the contact and exposure conditions and the calibration of measurement devices. The results indicate the limitations in the use of in-situ contact current measurements in occupational safety management system.

  9. K. Gryz, J. Karpowicz, Radiofrequency electromagnetic radiation exposure inside the metro tube infrastructure in Warszawa; Electromagnetic Biology and Medicine, Vol. 34, Issue 3, 2015, 265-273, doi: 10.3109/15368378.2015.1076447
    Abstract
    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. dy> sed subjects. Usually, the main attention is focused on the safety of patients undergoing medical procedure, for example, the use of electronic implants by patients was identified as a contraindication for various physiotherapeutic treatments. However, the attention is also needed for the proper identification of other mentioned EMF-related hazards in the medical environment near to any applicators emitting EMF during the patients’ treatment. The section discuss these topics without considering the safety of a patient who is the subject of EMF treatment.

  10. M. Fatahi,  J. Karpowicz, · K. Gryz, · A. Fattah, · G. Rose, · O. Speck,Evaluation of exposure to (ultra) high static magnetic felds during activities around human MRI scanners; Magnetic Resonance Materials in Physics, Biology and Medicine (2017) 30:255–264
    Abstract
    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.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).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.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. sed subjects. Usually, the main attention is focused on the safety of patients undergoing medical procedure, for example, the use of electronic implants by patients was identified as a contraindication for various physiotherapeutic treatments. However, the attention is also needed for the proper identification of other mentioned EMF-related hazards in the medical environment near to any applicators emitting EMF during the patients’ treatment. The section discuss these topics without considering the safety of a patient who is the subject of EMF treatment.

  11. S. Miclaus, P. Bechet, J. Karpowicz, Experimental Determination of Human Exposure in the Near Field of VHF Source: Correlations between Incident Field Strength and Currents Induced in Lower Legs of Persons –– 9th International Symposium on Advanced Topics in Electrical Engineering (ATEE), 7-9.05.2015, Bucharest, Romania; str. 408-412; DOI: 10.1109/ATEE.2015.7133838 [IEEE Xplore/Web of Science/Scopus]
    Abstract
    An experimental study was performed on seven human volunteers exposed in the reactive near field of a biconical antenna operating in the frequency range 30-110 MHz, in order to provide a preliminary framework for a further more complex study dealing with provision of a rapid and reliable procedure to assess personnel exposure to radiation emitted by nearby radio-communication antennas. Twenty experimental configurations were prepared for each individual to finally analyze the situation statistically. Incident field characterization - by electric field strength determination and body induced current measurement were accomplished. Challenging situations were encountered for reactive near field assessment. Significant correlations between incident field level and induced current were scarcely, being dependent on exposure configuration. Reliable correlations were however observed for a parameter described as `normalized current'.

  12. J. Karpowicz, Environmental and Safety Aspects of the use of EMF in Medical Environment [rozdział 21, str. 341-362 w monografii pt. Electromagnetic fields in biology and medicine, pod red. M. Markov, CRC Pres - Taylor & Francis Group; 2015]
    Abstract
    The electrodynamic effects of exposure to electromagnetic fields (EMFs) are used in medicine for therapeutic or diagnostic purposes. The devices used for such applications may emit EMF significantly stronger than typical environmental exposure and cause intentional exposure to patients undergoing treatment, as well as unintentional exposure to physiotherapists, surgeons, or radiographers, patients not undergoing treatment, and anyone visiting a medical center, as well as any electronic equipment present nearby, including medical implants. The effects of electromagnetic exposure of each of these subjects may influence the human body and electronic devices and may cause various health or safety hazards, such as excessive thermal effect, electrostimulation of tissues, projectile ferromagnetic objects, or electronic device malfunctions. Safety risks caused by EMF depend mainly on the field frequency, strength, and spatial distribution, as well as the characteristic and configuration of the exposed subjects. Usually, the main attention is focused on the safety of patients undergoing medical procedure, for example, the use of electronic implants by patients was identified as a contraindication for various physiotherapeutic treatments. However, the attention is also needed for the proper identification of other mentioned EMF-related hazards in the medical environment near to any applicators emitting EMF during the patients’ treatment. The section discuss these topics without considering the safety of a patient who is the subject of EMF treatment.

  13. K. Gryz, J. Karpowicz, W. Leszko, P. Zradziński, The frequency-selective evaluation of radiofrequency electromagnetic radiation in the public accessible indoor environment –– materiały konferencyjne EMC Europe 2014, 1-4.09.2014, Gothenburg, Szwecja; str. 381-384; DOI: 10.1109/EMCEurope.2014.6930936 [IEEE Xplore/Web of Science/Scopus]
    Abstract
    Frequency-selective exposimeters were used to evaluate exposure to radiofrequency electromagnetic radiation in 80 indoor public accessible locations (e.g. offices, libraries, shopping centres; in urban and rural areas). Exposures were characterised by statistical parameters.

  14. EU project EMF-NET: Effects of the Exposure to Electromagnetic Fields: From Science to Public Health and Safer Workplace – Final technical report on occupational EMF exposure (D49/MT2)

  15. EU project EMF-NET: Effects of the Exposure to Electromagnetic Fields: From Science to Public Health and Safer Workplace – Fact sheet on occupational EMF exposure (D49/MT2)

  16. K. Gryz, J. Karpowicz, W. Leszko, P. Zradziński,  Evaluation of exposure to radiofrequency electromagnetic radiation at an indoor workplace accessible by the public with the use of frequency-selective exposimeters, International  Journal of Occupational Medicine and Environmental Health (IJOMEH), 2014; 27(6), s. 1033-1044.
    Abstract
    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.

  17. K. Gryz, J. Karpowicz, Environmental impact of the use of radiofrequency electromagnetic fields in physiotherapeutic treatment, Roczniki Państwowego Zakładu Higieny, 2014; 65(1), s. 55-61.
    Abstract
    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 interference, 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 which 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.
    Streszczenie
    Wstęp.
    W rehabilitacji fizykoterapeutycznej wykorzystuje się pola elektromagnetyczne, które oddziałują nie tylko na pacjentów, ale także na fizjoterapeutów, pacjentów nie poddawanych tym zabiegom i aparaturę elektroniczną.
    Cel badań:
    Celem pracy była ocena oddziaływania pól elektromagnetycznych urządzeń fizykoterapeutycznych na funkcjonowanie elektronicznych urządzeń medycznych, w tym implantów, w kontekście bezpieczeństwa i zdrowia pracowników, pacjentów nie podlegających zabiegom i osób postronnych.
    Materiał i metody.
    Zbadano rozkład przestrzenny pola elektrycznego i magnetycznego przy 3 pojemnościowych diatermiach krótkofalowych i 3 długofalowych oraz 3 urządzeniach do terapii ultradźwiękami, a także pojemnościowe prądy elektryczne, płynące wskutek oddziaływania pola elektromagnetycznego przez kończyny górne osób obsługujących te urządzenia. 
    Wyniki.
    Narażenie fizjoterapeutów na pole elektromagnetyczne zależy od organizacji przestrzennej stanowiska pracy i miejsca ich przebywania w czasie zabiegu. Pole elektryczne, w którym możliwe są zakłócenia w funkcjonowaniu elektronicznych implantów medycznych i nie powinny przebywać w nim osoby nie podlegające zabiegom, stwierdzono w odległości do 150- 200 cm od aktywnych diatermii krótkofalowych, a do ok. 40-50 cm od diatermii długofalowych. W odległości do 30-40 cm od kabli i elektrod diatermii krótkofalowych stwierdzono pole elektryczne, w którym nie powinni przebywać pracownicy. Przy dotykaniu do elektrod i kabli aktywnej diatermii krótkofalowej, zmierzono pojemnościowy prąd elektryczny przepływający w ręku wielokrotnie przekraczający zalecenia międzynarodowe dotyczące ochrony pracowników.
    Wnioski. Najsilniejsze środowiskowe zagrożenia elektromagnetyczne występują przy aktywnych diatermiach krótkofalowych, przy diatermiach długofalowych znacznie słabsze, a przy urządzeniach do terapii ultradźwiękami nie stwierdzono takich zagrożeń.

 

 
01 Portal wiedzy o BHP - Centralny Instytut Ochrony Pracy - Państwowy Instytut Badawczy

Zobacz także