This paper reports the principles of design and the examined protective properties of liquid materials for shielding the electric, magnetic, and electromagnetic fields over a wide frequency range. The materials were made on the basis of iron ore concentrate and a pigment additive, with water-dispersed and geopolymer paints used as a matrix. The tests of protective properties for the electrical and magnetic components of the electromagnetic field of industrial frequency showed that the electric field shielding coefficients at a concentration of the screening substance of 15−60 % (by weight) equaled 1.1−8.6; magnetic field – 1.2−5.3. The shielding coefficients of the material based on a water-dispersed paint are lower than those of a geopolymer one, which can be explained by the oxidation of an iron-containing component and a decrease in electrical conductivity. The shielding coefficients of the electromagnetic field with a frequency of 2.45 GHz are 1.2−7.9. The highest coefficients are inherent in the material with filler made of iron ore concentrate and titanium-containing pigment powder in a ratio of 1:1. To design materials with the required (predictable) protective properties, the relative magnetic, dielectric permeability of materials was calculated. It is shown that the obtained data are acceptably the same as the results from direct measurements of magnetic and dielectric permeability and could be used to calculate the wave resistance of the material and the predicted reflection coefficient of electromagnetic waves. Thus, there is reason to assert the need to build a database on the frequency dependence of effective magnetic and dielectric permeability in order to automate the design processes of composite materials with predefined protective properties.

This paper reports a study into the quantitative values and dynamics of physical factors in premises and workplaces of stationary and portable computers. The factors that are practically not perceived by the senses of operators were investigated. It is established that modern monitors do not generate electromagnetic fields of hygienically significant levels. System units generate electric fields (18‒22 V/m) and magnetic fields (220‒245 nT) that are approaching the maximum permissible. Sources of uninterruptible power supply and fluorescent lighting systems generate excess magnetic fields (up to 2250 nT and 2300 nT), respectively. The main excessive factor for portable computers is electric fields (up to 9 kV/m), which is the cause of air deionization in the user's zone of stay. It is shown that one system unit in the normative volume of the room (20 m3) deionizes air (into 100 cm-3 positive and 200 cm-3 negative). The generation of ions by modernized laser printers and photocopiers of various models (up to 1500 cm-3 and 2800 cm-3, respectively) was investigated. The distances at which the ionic composition of the air corresponds to the background values (1.0‒1.5 m) were determined. That requires the introduction of artificial air ionization in workplaces of users and a decrease in the levels of electrostatic fields. The spectral composition and amplitudes of magnetic fields of external power supplies of laptop computers were determined. It is shown that the difference in sound levels measured on the scales "Lin" and "A" reaches 24 dB, which indicates a significant impact of infrasound on users. Membrane-type protective panels configured for maximum resonant frequencies of low-frequency sound and infrasound have been proposed

This paper reports a study into the possibility of using LED systems of ultraviolet radiation for air ionization and disinfection of air and indoor surfaces in the presence of people. It has been established that UV LED lamps with 120° opening angles have parameters under which radiation intensity does not exceed 30 J/m2 at distances of 2 meters. Based on experimental data, a methodology for designing the placement of lamps in the room was devised, which meets the requirements of the SBM-2015 standard and the European Directive 2006/25/EU. The use of LED emitters with a total intensity of up to 25 J/m2 increases the concentration of aero ions. The background concentrations were 140‒180 cm-3 (positive) and 160‒190 cm-3 (negative). The minimum permissible level is 500 cm-3. As a result of irradiation, the concentrations were 1100‒1460 cm-3 (positive) and 1260‒1470 cm-3 (negative). The influence of the recirculator-air purifier on the concentration of aero ions has not been established. The ionization process began immediately after turning on the irradiation systems in the entire volume of the premises (4‒5 meters from the source). The dynamic equilibrium of aero ion concentrations was established within 10‒15 minutes after the irradiation was switched on. The presence of a large number of people (up to 0.97 m2 per person) did not affect the concentration of aero ions. Under the combined effect of ultraviolet radiation and a recirculator-air purifier, the number of mold fungi colonies decreased by 20 times. Under the influence of only ultraviolet radiation – by 2.3 times. The decrease in the number of microbes under the combined effect was 1.6 times, and under the effect of only ultraviolet radiation – 2.8 times

A set of measures and means to control the electromagnetic situation of the environment in the territories of urban development, in buildings and individual premises has been substantiated and developed. The simulation tools show the ability to rationalize the parameters of overhead lines with voltages of 220 kV and below, which will reduce the electromagnetic load in the territories. Modeling the propagation of fields from underground high-voltage lines has established that the values of magnetic fields compared to overhead lines are lower up to 30 times. Models of propagation of electromagnetic fields of very high and ultrahigh frequency were built. Sources of electromagnetic fields of non-production origin in industrial buildings have been investigated. Uncompensated currents in power networks with nonlinear electric consumers generate magnetic fields by induction of 0.35−1.20 μT, which exceeds the maximum permissible levels of operation of computer equipment. Leakage currents on grounded metal structures generate magnetic fields with 1.52−6.75 μT. Simulation of the propagation of electric and magnetic fields of components of personal computers of controlled ranges according to the MPRII standard was carried out. Models of propagation of the magnetic field of industrial frequency around electric motors and generators with their cross sections were built. On the basis of such models, design schemes for placing equipment in production areas are selected or places of safe stay and movement of personnel are selected. The expediency of using shielding to reduce field levels to safe values due to coating surfaces with liquid protective mixtures was shown. Metal-containing composition based on water-dispersion paint makes it possible to reduce the level of magnetic field of industrial frequency by 2.5−2.6 times, electric field by 1.6−1.7 times, electromagnetic field of industrial frequency – by 1.2−1.3 times.

In the modern world, protection against the influence of man-made electromagnetic fields shielding will be increasingly used. In the transition to international standards (in various industries) in the manufacture of the latest facing and finishing materials, the most promising and demanded building materials with shielding properties. Reducing weight due to the thickness of the shielding coating of building material is not always expedient and is not always allowed by the relevant state and international sanitary norms. Theoretical calculations on this issue or mathematical forecasting minimize the cost of manufacturing the substance of the shielding material, and in general, reduce the total number of measurements to their confirmation. The presented methodology enables to predict protective properties, depending on the parameters of fields that need shielding. The purpose of the study is – the manufacture of the latest coatings of composite structures to predict the protective properties of building materials in a wide frequency range. Methods and methods of research – improvement of the development of a new shielding material by producing metal-polymer material for shielding physical fields and developing a technology for increasing the distribution of shielding particles in the body of a polymeric material (matrix), preventing particle adhesion and increase their dispersion.