Nitrogen for mining & tunnelling dramatically increases safety during the operation. Tunnel sections that are being worked on are often blanketed by nitrogen to avoid fires and explosions.
In case of a fire in a tunnel section, nitrogen can serve as a fire extinguisher eliminating all the oxygen in the tunnel and quickly putting fires out. Thanks to its invertibility, it has rapidly become an essential part of mining and tunnelling operations safeguarding the entire project. More about tunnelling here.