In 2016, limits for NO and NO2 have been reduced in Germany to 2 and 0.5 ppm respectively. In mining operations, it was not possible to reduce emissions below these values. For this reason these limits are not valid for mining until 2021. Emission sources for NOx in mines are mainly exhaust fumes from diesel engines and explosives. Due to the introduction of diesel engines in the subsurface in the 60ies, the ventilation became a challenge. Volume flows have been increased drastically. Since this time, a lot was done to reduce diesel motor emissions. CO could be used as leading component in the air. That means if concentrations of CO were under the limit, it could be assumed that also NO and NO2 are under the limit values. But the introduction of the new reduced TLV´s is again a challenge. Theoretically, 10 times more volume flow is needed resulting in a too high air-velocity in the drifts ore shafts with diameters of more than 20 m. An instant transition from diesel to electric driven vehicles is not possible for several reasons (availability, costs, infrastructure,
). Furthermore, measurements have shown that even with electric equipment, emissions from blasting fumes exceed the TLV´s. Here the problem is not the cloud of blasting fumes after the blast, but the blasting fumes which remained in the muck. Consequently, the focus is now on the development of new explosives with drastically reduced NOx concentrations in the blasting fumes. Furthermore, CO is no longer the leading component for underground gas measurements. And new sensors had to be developed which can measure concentrations not only in ppm like in the past but in ppb.