Environmental problems caused by coal energy may be regarded in terms of various components: mining, transportation, and combustion and waste disposal. The environmental considerations include the emission of dust to the atmosphere and chemicals to groundwater; land subsistence in underground mining and land reclamation in surface mining; disposal of mine waste; miners' safety; and water consumption, especially in dry areas. Transportation problems include dust and water pollution (mainly from storage piles); traffic noise and congestion; and accident risk. Combustion and waste disposal elicit the most concern due to the oxides, monoxides, dioxides, trace minerals and volatile elements of which the flue gases are composed.
In China rapidly increasing energy generation from coal, three-quarters of which is for industrial or electric power use, has led to some of the world's highest concentrations of fine particulates and sulphur oxides, some of the most acidic rainfall in the world, and chronic obstructive pulmonary disease five times more prevalent in urban populations than in the United States.