Chemical, Air Dust Pollution Underground mining allows coal companies to dig for coal deeper into the ground. The problem is that huge amounts of earth and rock are brought up from the bowels of the earth. These mining wastes can become toxic when they are exposed to air and water. Examples of toxins are mercury, arsenic, fluorine and selenium. Mining in India is a major economic activity which contributes significantly to the economy of India. The GDP contribution of the mining industry varies from 2.2% to 2.5% only but going by the GDP of the total industrial sector it contributes around 10% to 11%. Coal with a proven reserve of 860 billion tonnes is mined the most in the world.