Depending on the type of mining, the requirements for gas detection can vary greatly, however, there are five main sources of hazardous gas in mining applications.

1. Gases from Blasting:
Gases resulting from blasting are principally carbon dioxide, nitrogen and steam.  However, toxic gases including carbon monoxide and nitrogen dioxide also result.  As oxygen is consumed in any such blast, oxygen deficiency may also be a result.

2. Methane from Coal Beds:
Highly combustible methane (CH4) or firedamp, as it is called in many coalfields, is formed in the latter stages of coal formation, and because of the depths and pressures, it becomes imbedded in the coal.  As excavations are made, methane gas is liberated into the air.  Gas is emitted not only from point of excavation, but also from the coal being transported to the surface.

3. Vehicle Exhaust:
As with any other vehicle exhaust application, toxic fumes are a result of the operation of internal combustion engines.  In mining diesel vehicles are used primarily, and carbon monoxide and nitrogen dioxide, as well as oxygen deficiency are of concern.

4. Underground Explosions and Fires:
Even small, smoldering fires can create toxic gases including carbon monoxide and nitrogen dioxide, and also consume enough oxygen to cause asphyxiation.

5. Drilling into Stagnant Water:
Pockets of stagnant water can contain large amounts of hydrogen sulfide resulting primarily from the breakdown of pyrites.

Because of the diversity of mining applications, any or all of the sources listed above may contribute to air quality issues, and your application should be looked at on an individual basis to determine which hazards may apply.