A report commissioned by Greenpeace estimates that the hidden cost of coal exceeds $170billion every year. This includes the cost of respiratory diseases, and the contribution that burning coal makes to climate change. It notes that while coal is usually considered a cheap source of energy, this is largely because most of the costs of mining and burning it are borne by society, not by the energy industry. Australia exports more than ten percent of the coal shipped in international markets.
The full report is availabe from the Greenpeace website.