The effectiveness of the miners’ respirators

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.