Coal used for this process is called steaming coal. In 2008 77% of the electricity generated in Australia was produced by coal fired power stations (includes black and brown coals). Some types of black coal are suitable for coke-making.
These symptoms may occur in the back, leg and down to the foot. The most common nerve irritation originating from the lumbar spine is Sciatica. This is an irritation of the sciatic nerve, which can produce pain, numbness, and weakness down the leg along the areas innervated by the sciatic nerve.
The close approximation of the sciatic nerve is the reason that increased tone of the piriformis muscle could cause irritation to the sciatic nerve. Irritation to the sciatic nerve in patients with left psoas syndrome often causes pain that radiates down the back of the right leg and stops at the knee.