Two studies were conducted in the coal mines to evaluate worker exposures to a dust, and the effectiveness of air-purifying negative-pressure half mask respirators and was found that miners’ protection were insufficient. An elastomeric and filtering half-mask negative pressure respirators with (mid-efficiency) filters P2 (FFP2) were studied. Measurements of total dust concentrations in the in-mask and outer air were conducted simultaneously. Not identical sampling system led to an underestimation of the actual total inside dust concentration in the first study. The results have been corrected to reduce the systematic error. The inside total dust concentrations Ci exceeded national Permissible Exposure Limit (PEL) in most cases in both studies; in first GM Ci=24.7 mg/m3; in second 8.6 mg/m3. Protection factors were: from 2.9 to 6.9 in first study; and from 5.6 to 34 in second. Low efficiency of respirators can be caused by its non-continuous usage. High risk of miners’ occupational diseases should be reduced by decreasing the dust concentration in the breathing zone. It is advisable to check the possibility of improving respiratory protection of miners by powered air-purifying respirators.

Purpose. To define coefficient of protection of filtering respirators with elastomeric half-masks PR-7 in conditions of coal mines.Methods. Antidust respirators applied at mining enterprises of Ukraine were tested for determination of their protective efficiency.Findings. As a result, it was found that the protection coefficient of the provided half-masks is in the range from 5 to 34. The main reasons of half-masks protective properties deterioration are poor insulating properties of half-masks, their design defects, improper use, application of respirators in case of unacceptably high concentration of dust and also lack of standard sizes of half-masks for operating.Originality. It has been established that the value of protection coefficient in case of dust content growth due to increasing dust coarse fraction, which in combination with high moisture will quickly fill gaps on an obturation line and thereby will reduce penetration in under mask space of the half-mask. Practical implications.The received results indicate that the half-mask respirators of the PR-7 type of samples 1 and 4, used by miners, allow to provide effective protection according to DNAOP 0.00-1.04-07 "Regulations of selection and use of personal protection equipment of respiratory organs", in case of their use up to maximum allowable concentrations 12.

Purpose. To improve the occupational risk management system to increase the security stability of the enterprise in emergency situations. Methodology. The theory of system dynamics on the basis of which a dynamic Rasmussen model is built, describing the "movement/drift" of an industrial enterprise before an emergency occurs under the influence of three main external factors: economic, social and technological. Research results. It has been proposed to improve the occupational risk management system for monitoring and preventing the occurrence of COVID-19, which provides for the justification of appropriate measures in the economic, social and technological spheres of the enterprise in accordance with the identified opportunities and existing constraints. Two scenarios for the development of events in the conditions of pandemic have been considered, the strengths and weaknesses of each of them and possible consequences for the enterprise have been outlined, which allowed to develop the algorithms for assessing the risks and opportunities of enterprises facing the pandemic. Recommendations to strengthen the economic stability of the enterprise and increase the stability of its security have been made. Scientific novelty. The impact on the security stability of the pandemic has been determined, which made it possible to set the limits for external factors that reduce the risk of emergency. Practical significance. Recommendations have been developed to reduce the impact of the pandemic on the security stability of the enterprise.

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Introduction. Dust is one of the main harmful factors in underground coal mining. The dust concentration in the coal mines remains high due to the imperfection of the used technologies, increasing the pneumoconiosis risk in miners. Respirators are the last means of protection, but information about their effectiveness is contradictory. Aim. Assess the effectiveness of individual respiratory protective devices in the coal mines. Material and methods. The protection factor (PF), the ratio of the dust concentration outside the mask to the concentration under the mask) is used to assess respirators’ effectiveness. We measured the PFs in the laboratory and the workplaces. We also measured the time the miners did not use respirators. The measurements’ results were used as input data for mathematical modeling to reduce dust load reduction. Results. The concentration of dust under the mask exceeded the Occupational Exposure Limit (OEL) in most cases. Information about the high efficiency of the negative pressure half-mask respirators (in case of continuous use) was not confirmed. The PFs measured under laboratory conditions reached 6.2, and in the workplace were from 5 to 31. The miners did not use respirators from 10 to 45% of the shift duration (15 measurements). The measurements and information on the concentration of dust in 5 mines were used to simulate the impact of the respirators’ usage on the dust load. Calculations performed by different methods, and using various programs, gave the same result. The negative pressure half-mask respirators cannot reduce the dust’s concentration in the inhaled air to the OEL even with continuous use. Conclusion. The results showed that the respirators’ usage could not prevent developing incurable pneumoconiosis in miners.