# Assessment of the Dust in Underground Coal Mine
## 3 Results  
### Measurement of Airborne Dust in the Mining Field  
Using the described procedures, dust concentration values were calculated and appropriate types of disconnecting mechanisms were assessed for dust production when the mining section was loaded with a certain number and type of active workplaces. For the month of February, the measured values are shown in Table 1.  
The development of dust in the 11 th mining field during I, II, and IV occurred mainly on the mechanized cutting 111 021-95 of the staff team X1 with mechanized support BMV--Mi with a total number of 42 pieces. The mechanized boring of the opening corridors of the future wall cutting with the designation 111 023-95 was affected partially by the boring in corridors 111 123-05 by the staff team X2 and 111 223-05 by the contractor LGO. During this period, we can assess the airborne dust as excessive due to the occupation of the mining section by a larger number of teams. In the third week of February, dust concentration levels were reduced due to the temporary suspension of work on the mechanized boring plant and the withdrawal of teams to other mining sections. At that time, there was only one active workplace in the mining section. For the month of March, the measured values are shown in Table 2. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Sampling** & **Day of Sampling** & **Place of Sampling** & **Stationing of Sample (bm)** & **Total Concentration** \\ \hline I. & 8 March 2023 & 08 240 & 220 & 28 \\ \hline II. & 15 March 2023 & 08 240 & 220 & 25 \\ \hline III. & 22 March 2023 & 08 240 & 220 & 39 \\ \hline IV. & 29 March 2023 & 08 240 & 220 & 38 \\ \hline V. & 1 April 2023 & 08 240 & 220 & 7 \\ \hline Average (mg\(\cdot\)m\({}^{-3}\)) & & & & 27.4 \\ \hline Standard deviation & & & & 12.93 \\ (mg\(\cdot\)m\({}^{-3}\)) & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Measurement of airborne dust in March 2023. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Sampling** & **Day of Sampling** & **Place of Sampling** & **Stationing of Sample (bm)** & **Total Concentration** \\ \hline I. & 8 March 2023 & 08 240 & 220 & 28 \\ \hline II. & 15 March 2023 & 08 240 & 220 & 25 \\ \hline III. & 22 March 2023 & 08 240 & 220 & 39 \\ \hline IV. & 29 March 2023 & 08 240 & 220 & 38 \\ \hline V. & 1 April 2023 & 08 240 & 220 & 7 \\ \hline Average (mg\(\cdot\)m\({}^{-3}\)) & & & & 27.4 \\ \hline Standard deviation & & & & 12.93 \\ (mg\(\cdot\)m\({}^{-3}\)) & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Measurement of airborne dust in February 2023. In the first two weeks, only three active sites were located in the 11 th mining field, there was one mechanized cutting and two mechanized borings. During this assessment period, mechanical rock disconnecting, breakdowns on the sprinkling mechanisms of the mining and boring machines and the transport of the rubble contributed to the development of the dust. In the period of weeks III and IV in the 11 th mining field, two active mechanized boring staff teams X3 and X4 were added in the boring of the future wall cutting marked 111 022-95 in the 111 122-05 and 111 222-05 corridors. During the evaluation period, the expansion of the wall breakthrough was proceeded with the subsequent installation of mechanized support in the 111 023-95 wall cutting. After the last sampling was performed and evaluated, the total specific dust concentration from the 11 th mining section was found to be 14 mg\(\cdot\)m\({}^{-3}\). In Table 2 we can see that this is the lowest calculated value. Taking into account the total exposure of the underlying measurement, 48 h, then, on average, the dust concentration per day at the end of March is 7 mg\(\cdot\)m\({}^{-3}\).