India is a country with more than 1.32 billion people accounting for more than 17.74% of the world’s population. Coal has played a significant role in the development of India. Total coal reserves are about 860 billion tonnes in the world and procurable only next 120 years at the current rate of production . India is the third major coal producer in the world after China and USA. Global coal reserves are about 7.0 % (301.80 billion metric tonnes) and production is 8.75% (538.76 million metric tonnes) in India, in 2016.
Major coal reserves states are Jharkhand (81.7 billion metric tonnes), Odisha (75.90 billion metric tonnes), Chhattisgarh (56.04 billion metric tonnes) West Bengal (31.53 billion metric tonnes), Madhya Pradesh (26.91 billion metric tonnes) in India  Quality of Indian coal is poor which contain high percentages of ash 22.52 to 50.47 wt.%, mineral cont ins matter 5 to 20 wt.%, carbon 25-30 wt.%, Sulpher 0.5 wt.% and calorific value 2450-3000 kcal/kg . Population exploration, rapid economic growth, and a luxurious lifestyle are exploring the energy demand. Fossil fuel, coal is the cheapest source of energy across the world.
About 40% of electricity production is from coal combustion in the world  where India shares about 60.0% . Availability of electricity has enhanced the quality of life, but on the other side, it oppresses the environment and health due to released pollutants from coal combustion for electricity generation .
Indian power generation growth rate was 5.64% in 2015-16 . Energy consumption in India is 128 watts/person compared to 1377 watts/person in the USA, and 492 watts/person in China with an average of 309 watts/person in the world. The energy demand is expected to cross 8, 00,000 MW by 2030 in India .
About 132 CTPPs are producing 1, 86,213 MW of electricity, which is 61.15% of the total installed capacity of 304505.75 MW in India as of June 2016 . Indian CTPPs are emitting more pollutants per unit of energy production compared to European/Australian power plants due to low-grade coal and poor plant efficiency. Global average coal thermal power plant efficiency is high, 33 to 40% compared to Indian CTPP efficiency 29-32%. Governments have been planned to establish>40 percent efficiency and looking forward to replacing 2020, those coal-fired power plants built over 25 years old. National Thermal Power Corporation (NTPC) has collaborated with Indira Gandhi Centre for Atomic Research (IGCAR) and Bharat Heavy Electricals Limited (BHEL), to reduce the emission of pollutants. Japan has provided technical support by introducing high-efficiency power generation technologies. Fly ash is a by-product of coal combustion at high temperatures (about 1250 ̊C) in CTPP. About 35 heavy and trace cum toxic elements are present in fly ash, including Al, As, Cd, Co, Cr, Cu, Pb, Ni, planningHg, Se, and Si  and contain carcinogenic organic compounds like chloro-phenol, chloro-benzene, polychlorinated dibenzo are shown to be concentrated on particle surface which accelerates deterioration quality of environmental. The generation rate of fly ash is about 131.09 million tonnes per year . Proper disposal, recycling, and sustainable utilization of fly ash are at least 20-35 % in India as compared to other countries. Negligence disposal of fly ash released toxic metals and other compounds which are hazardous to the environment and human health.
Stack emission from CTPP is a complex mixture of particulate matter (PM), SO2, NOx, CO2, CO, trace elements including arsenic, lead, mercury, acidic gases (HCL and HF), hydrocar¬bons (PAHs), and radioactive elements. The hazardous impact of a CTPP has been found more than 100 km . Under windy conditions, pollutants were carried distances more than 500 km from the source . Annual anthropogenic contributions from CTPP emission are accounted for wt. 15% for PM2.5, wt. 50% of SO2 and wt. 30% for NOx in India . Emission standard for >210MW are PM 30mg/Nm3, SO2 100 mg/Nm3, NO2 100 mg/Nm3, mercury 0.03 mg/Nm3 in India. Mercury is a highly neurotoxic heavy element. Power plants are a major anthropogenic point source of mercury. Mercury content in Indian coal is 0.01 to 1.1 ppm and India, one of the mercury hotspots in the world, is adding 26 percent (339-657 metric tonnes/year) of mercury to the global atmosphere . PAHs, traces, and heavy metals are associated with the surface of fly ash, which has hazardous properties and is a threat to air quality, the environment as well as human health. Air pollution accelerated chronic cardiovascular, respiratory disease, or lung cancer  and increases illness and the number of deaths in the general population in the vicinity of a coal thermal power plant .
Worldwide, five percent of deaths are due to air pollution . PM2.5 is more destructive compared to PM10 because it contains toxic ingredients and enters into blood circulation through the alveoli . Exposure to PM2.5 can accelerate the development of atherosclerosis and increase congestive heart problems . About 151 million minor illnesses, about 2 million serious ill¬nesses, and 210,000 deaths are per year from the pollution of CTPP . Deaths cost by air pollution to the global economy are $225 billion . For that reason, the Pollution load index(PLI) and Hazard Index (HI) studies are essential for identifying the regional impact of CTPP. According to the calculated Hazard Quotient (HQ), for non-cancer effects, the ingestion of dust appears to be the major route of exposure that results in a higher risk for heavy metals, followed by dermal contact and inhalation pathways. However, compared to inhalation and dermal contact exposure, exposure through ingestion is almost negligible. Hazard Index (HI) values for all studied elements were lower than the safe limit of 1 and this result suggests that the population groups would likely experience potential health risks due to exposure to heavy metals from coal thermal plants in the study area.