1. Introduction

Unfavourable conditions of industrial environment against the background of socio-economic well-being have a negative impact on the state of health of the working population of the republic. In workers of mining industry [2,5], especially underground mines in the structure of general pathology the leading place belongs to diseases of cardiovascular system [4,9]. In terms of prevalence, severity of course, complications, cardiovascular diseases are one of the main causes of disability, disability, premature death of men of working age [10,13].

Currently, the pathogenetic relationship and prognostic significance of diseases of the cardiovascular system caused by exposure to harmful industrial factors are insufficiently studied [7,12]. Interest in the study of interorgan connections in the pathology of a number of diseases does not lose its relevance [3]. Despite a considerable number of works devoted to this problem, the issues of causal relationships between the factors of industrial environment and the development of cardiovascular system pathology in workers of mining industry remain poorly studied [1,6].

Consequently, the study of the influence of a complex of production harmful factors on the health of workers in the mining industry remains a priority task of public health and is an urgent problem [8,11].

Purpose of the study: Hygienic assessment of working conditions of workers in the main occupations of underground mines.

2. Materials and Methods

The working conditions of the main occupations of underground subdivisions of the mines Razvedochnaya, Kairagach, Semguron and Samarchuk were studied. A total of 240 workplaces were studied, where 649 people work. Of all employees 433 people work in underground conditions in contact with harmful production factors exceeding the norm.

The main professions working in conditions of exposure to dust, chemical (nitrogen oxide, sulfur dioxide, carbon oxide) and physical factors (noise, vibration, increased atmospheric pressure), unfavourable meteorological factors, severity and tension of the labour process are tunnellers, loading machine operators, loading and delivery machine operators, explosion operators, fasteners, drilling rig operators, underground miners.

To study and assess the impact of a complex of production factors on the organism of workers, the occupational groups were selected, which were affected by the most harmful and hazardous factors of the production environment: 7 occupational groups Exploration mine (283 people) Kairagach mine 7 occupational groups (177 people), Semguran mine 4 occupational groups (70 people) and Samarchuk mine 6 occupational groups (119 people), a total of 649 workers. Labour conditions of these workers were studied in different seasons of the year with identification of the main production factors. In the dynamics of the working day, measurements were made of the parameters of dustiness and contamination of the air of the working zone, noise and vibration, severity and tension of the labour process.

Studies on acoustic characteristics of permanent and non-permanent noise, parameters of local vibration at workplaces were carried out with the help of the device VSHV-003 MZ in accordance with the SSBT GOST-12.1.050-86 ‘Methods of noise measurement at workplaces’. Hygienic assessment of the measured noise and vibration levels for compliance with their permissible levels for permanent and non-permanent workplaces of production premises was carried out in accordance with SanPiN RUz #0325-16 ‘Sanitary norms of permissible noise levels at workplaces’ and SanPiN RUz #0326-16 ‘Sanitary norms of general and local vibration at workplaces’.

General assessment of working conditions by class and degree of harmfulness was carried out in accordance with the ‘Methodology for assessment of working conditions and certification of workplaces by working conditions’, SanPiN RUz № 0141-03 ‘Hygienic classification of working conditions by indicators of harmfulness and danger of factors of the industrial environment, severity and tension of the labour process’. Occupational risk was determined in accordance with the ‘Methodological Guidelines for the development of occupational risk prediction model and preventive measures for workers’ health’.

3. Result and Discussion

We studied the working conditions of the main occupations of underground subdivisions of the mines Razvedochnaya, Kairagach, Semguron and Samarchuk. A total of 240 workplaces were studied, where 1103 people work. Of all employees, 649 people work in underground conditions in contact with harmful production factors exceeding the norm.

To identify harmful production factors, to establish the level of these factors, 53 workplace attestation cards (2018), protocols of laboratory-instrumental measurements performed within the framework of scientific research of the laboratory of diagnostics, treatment and prevention of occupational diseases of the Research Institute of Sanitary Hygiene and Occupational Diseases of the Ministry of Health of the RUz were analysed.

The main professions working in conditions of exposure to dust, chemical (nitrogen oxide, sulphur dioxide, carbon oxide) and physical factors (noise, vibration, increased atmospheric pressure), unfavourable meteorological factors, severity and tension of the labour process are tunnellers, loading machine operators, loading and delivery machine operators, explosion operators, fixers, drilling rig operators, underground miners.

Vibration on all machines has a broadband character, with maximum energy at low frequencies of 2-4 Hz. The drivers of the loading machine driver and the driver of the loading-delivery machine are affected by the general transport-technological vibration, which corrected equivalent levels of vibration velocity for the working shift were 107 and 107.2 dB exceeding the MPL (with the norm - 101 dB). On the vertical axis Z the maximum level, which is observed in octave bands 2-4 Hz and exceeds the MPL by 6 and 6.2 dB.

At the working chair of the drilling rig operator, the corrected equivalent levels of vibration velocity for the working shift were 106 dB, respectively, exceeding the MPL of general vibration of category 3a - technological - 9 dB with the standard - 92 dB. The highest measured levels of vibration velocity were observed during drilling work on Z axis - 124, 119 dB - in octave bands of frequencies 4 and 8 Hz and on X and Y axes - 98-101 dB in octave bands of frequencies 16 and 31.5 Hz (Table 1).

Table 1. Level of general vibration at workplaces of main occupations underground mines

The estimation of industrial vibration level according to the corrective equivalent level showed the excess at the workplaces of the tunnelling machine operator - 115 dB, loading machine operator, loading and delivery machine operator, drilling rig operator - 114 dB, compressor unit operators - 112 dB (with the norm 101 dB) (Table 2).

Table 2. Level of local vibration at workplaces of the main occupations of underground mines

Depending on the machines and mechanisms used, workers may be affected by local vibration transmitted to the hands when holding the tool, or general vibration - with its transmission to the whole body through the floor, seat. When drilling, tunnellers are exposed to local vibration exceeding the MPL by 3 dB. In a number of professions there is a combined effect of broadband noise, general vibration of the workplace and local vibration on the controls (loading machine operator, loading and delivery machine operator, drilling rig operator). It is important to emphasise that when operating different mining machines and mechanisms, vibration levels and the nature of its impact on the worker are significantly different.

4. Conclusions

The results of hygienic studies have shown that in the process of labour activity of miners there is an impact of a complex of unfavourable production factors, the leading of which is noise-vibration, reaching maximum intensity in the miners of the underground mines under study.