Coal breaker remaining. The sorting by size is particularly important for anthracite coal. In order to burn efficiently, air must flow evenly around anthracite. Subsequently, most anthracite coal is sold in uniform sizes. In the 1910s, there were six commercial sizes of coal (with the smallest size having three subsets): Coal pieces smaller than in size were considered "culm," and unable to be separated from the impurities (and thus useless). The grade of coal ranged from a low of 5 percent impurities for steam or broken coal to a high of 15 percent for pea-size coal and its subsets. Coal breakers were
Environmental impact of the coal industry to form fine particles and ground-level ozone and are transported long distances, making it difficult for other states to achieve healthy levels of pollution control. The wet cooling towers used in coal-fired power stations, etc. emit drift and fog which are also an environmental concern. The drift contains Respirable suspended particulate matter. In case of cooling towers with sea water makeup, sodium salts are deposited on nearby lands which would convert the land into alkali soil, reducing the fertility of vegetative lands and also cause corrosion of nearby structures. Fires sometimes occur in coal beds underground. When coal beds are