Coal was formed by in swamps which captured energy from the Sun of years ago. All living things contain which comes from the proteins in the cells. Sulphur is therefore found in coal. It is found as hydrogen , a poisonous gas smelling of rotten eggs.

When the coal is burned, sulphur is burned, reacting with oxygen to form sulphur . This in turn reacts with to make sulphurous acid. The rain is dilute sulphurous acid, with a of about 2. It reacts with , so that the limestone is away.

Sulphur is also found in diesel fuel.

The sulphur is removed at power stations using . The sulphur dioxide reacts with limestone to give calcium .