1 1 gram of SO 2 for every million mL of air (parts per million by mass per volume). 2  Write ppm in terms of cubic meters. 3  There are a million cubic centimeters in a cubic meter (1 cm 3 = (10 -2) 3 m 3 = 10 -6 m 3) so one part per million of SO 2 by volume in air is actually 1 cm 3 SO 2 / 1 m 3 of air. 1 gram of SO 2 for every million grams of air (parts per million by mass); 2  1 mL of SO 2 for every million mL of air (parts per million by volume); 3  1 gram of SO 2 for every million mL of air (parts per million by mass per volume). 4  Write ppm in terms of cubic meters.
Mining is classified by the method needed to reach the coal seam. When the coal is found close to the Earth's crust and taking away the overlying layers of material is not too expensive, surface mining is used to remove the top layers of materials and expose the coal.If coal is found in layers far from the surface, underground mining is the preferred technique.Vertical or slanted holes (shafts) are cut down to the mining area underground for ventilation for the workers and for transporting the miners, equipment, and coal.ining is classified by the method needed to reach the coal seam. When the coal is found close to the Earth's crust and taking away the overlying layers of material is not too expensive, surface mining is used to remove the top layers of materials and expose the coal.
A third of the coal is mined in the Appalachian Coal Region where the larger mines are underground and the smaller ones are surface mining. West Virginia produces the most coal for this region and is the second largest coal producing state in the country.eeper coal beds can be found up to one thousand feet below the earth. Miners tunnel underground to get this coal. This is the most dangerous kind of coal mining. If a mine shaft collapses, miners can become trapped and miners are at risk to develop black lung disease after a career of breathing the coal dust.