Seam gases are the most important atmos- phere contaminants in Australian collieries, their importance increasing with depth; C02 as well as CH4 may be important in intruded envir- onments. The generally high rank of the coal, with low moisture content, makes for abnormal dust production. The other contaminants are introduced and subject to better control, in- cluding products of spontaneous combustion._x000D_
Due to market situations the generally lower rank and higher sulphur coals more prone to self heating are mined less. Future mining at greater depths should see greater problems with atmosphere contaminants.