## 7 Conclusions  
A fire in an underground mine is a major source of risk for workers. In fact, in a confined environment, the fire can evolve very quickly, and the produced toxic fumes can reach the miners in the active site where they operate or along the escape routes to the surface.  
The diesel vehicles operating in underground mines use a considerable amount of fuel; it is not uncommon for some anomaly to occur and cause an instance of overheating or a spark to start a fire. The presence of ventilation inside the mine is an aspect that must be properly considered for its effects on the evolution of the fire and on the movement of toxic fumes.  
For a detailed analysis of fires in underground mines, it is necessary to use numerical modeling. Thanks to this, it is now possible to study the effects of an underground fire on the environmental conditions in the mine and, in particular, to verify the propagation, over time, of the toxic fumes.  
In this paper, different fire scenarios were studied in an underground gypsum mine in northwest Italy. For each of the hypothesized positions of a fire due to a diesel vehicle, it was possible with the Ventsim 5.4 calculation program to evaluate the propagation of toxic fumes (in particular, carbon monoxide and carbon dioxide) and the available time to allow a safe evacuation. For each examined case, the strategies for choosing the escape route and managing the mine's main fan were evaluated.  
The conducted study represents a successful application of sophisticated calculation methods regarding a coupled analysis of ventilation and underground fires in mines. This was conducted as a useful support for the definition of emergency plans that are capable of guaranteeing the safety of personnel in high-risk conditions. In fact, it was possible to identify the suitable escape routes for evacuating personnel for the various assumed fire scenarios, as well as the management strategies that are to be adopted in the event of an emergency. In the event of a front loader fire at the deepest level, i.e., Level F, as an example, it is necessary to deliver an immediate evacuation order to the personnel toward the San Pietro ramp and to immediately reverse the main fan of the mine, thus guaranteeing the abandonment of the deepest levels within the available 6 min.  
The evolution of studies and research in this delicate area of mining safety will have to be concerned with the implementation of emergency plans on a probabilistic basis, determining what is the probability of survival for each individual miner when a fire is triggered on a vehicle or plant at a specific point of the mine. These probabilistic studies will have to take into account all the machines or plants that are present in the mine and, therefore, also the probability that a fire will start in a particular area; in the same way, the probability that each individual miner is located in the various possible areas in which they operate must be considered. The probabilistic studies will have to use the same three-dimensional numerical models illustrated in this paper, as well as having to demonstrate that they are able to evaluate the time available to the miners to be able to safely undertake the escape route, specifically before the toxic fumes of the fire make the atmosphere unbreatable.  
Conceptualization, A.N.S. and P.O.; methodology, A.N.S. and P.O.; software, A.N.S. and P.O.; validation, A.N.S., P.O. and S.G.; formal analysis, A.N.S. and P.O.; investigation, A.N.S., P.O. and S.G.; resources, A.N.S. and P.O.; writing--original draft preparation, A.N.S., P.O. and S.G.; writing--review and editing, A.N.S., P.O. and S.G. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The authors declare no conflict of interest.