# Coal Dust and Methane as a Hazard in Coal Preparation Plants
## 4 Discussion  
The analysis of coal dust and methane explosion hazards in coal preparation plants highlights significant trends and evolving risks over the two decades from 2003 to 2022. The period was characterized by substantial organizational changes within the Polish hard coal mining sector, including a sharp decline in the number of operational mines and coal production volumes. Despite these reductions, certain hazard indicators show concerning upward trends, reflecting complex relationships between workplace safety and operational adjustments. The total number of workplaces in explosive dust atmosphere zones (zones 20, 21, and 22) exhibited a strong correlation with coal production, as evidenced by a Pearson coefficient of 0.945. This finding aligns with the general expectation that fewer mines and lower production volumes would reduce workplace hazards. However, the share of workplaces in high-risk zone 20 increased relative to the total number of workplaces in explosive zones, even as overall production declined. The calculated index IEZ\({}_{20}\) demonstrated a negative correlation with production (\(r=-0.592\)), suggesting that high-risk areas may persist despite overall safety improvements. This is a surprising result that may indicate an obsolete infrastructure and inefficient safety measures. The findings of this study align with the work of [PERSON] et al. 2023 [37], who employed the Systems-Theoretic Accident Model and Process (STAMP) combined with the Rank-order Centroid (ROC) method to identify critical risk factors in non-coal mine explosion accidents. [PERSON] et al. 's emphasis on systemic risks--such as inadequate licensing, confusion in safety management systems, and failures in supervision--might reflect some of the hassle in Polish coal preparation plants. Their approach offers a valuable framework for improving  
Figure 7: Changes in calculated IMC index and average annual methane content in coal from 2000 to 2022.  
risk identification by integrating broader systemic considerations into hazard assessment methodologies. [PERSON] et al. 2023 [PERSON] et al. (2023) highlight the critical role of human factors in explosion hazards. Their study shows that unsafe acts--such as habitual violations driven by mental state and other factors--are significant contributors to coal mine gas explosions. This aligns with our findings that, despite declining production, the proportion of workplaces in high-risk zones continues to grow. These insights underscore the need to address behavioral and organizational factors alongside physical hazards. Integrating frameworks like the Human Factor Analysis and Classification System (HFACS-GE) and Bayesian Networks (BNs) could help identify and mitigate unsafe acts, enhancing safety compliance in coal preparation plants. On the other hand, technological advancements such as positive-negative pressure dust removal systems [PERSON] et al. (2020) can play a pivotal role in dust control. Their study showed that a positive- and negative-pressure composite dust removal system reduced average dust concentration in coal preparation plants by over 78%. The IMAC index, representing workplaces exceeding the Maximum Allowable Concentration (MAC) for dust, did not show a clear trend over the analyzed period. The weak Pearson correlation coefficient of 0.145 suggests no consistent relationship between coal production and dust-related hazards. This may reflect variability in workplace conditions, safety measures, or monitoring practices, rather than a direct influence of production volumes. Fluctuations in IMAC index may be also attributed to changes in coal geology where access to coal with a higher silica content may be encountered. This is in line with a broader studies [PERSON] et al. (2020); [PERSON] et al. (2020) in US mines, which show large variations in silica content depending on the strata and distance from longwall operation.