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Introduction

-Combustion of fossil fuels have been a major problem in twentieth century.
-Currently fossil fuels supply 86% of the global primary energy for transportation, industrial, commercial and residential use.
-This means a lot of emissions of pollutants which lead to greenhouse effect
-Combustion of fossil fuels generates sulfuric, carbonic, and nitric acids, which fall to Earth as acid rain, impacting both natural areas and the built environment.
-Monuments and sculptures made from marble and limestone are particularly vulnerable, as the acids dissolve calcium carbonate.
-Incomplete combustion processes can emit organic pollutants, metals, and fine particles.
-The gases emitted from vehicle, factories, spray cans and by the combustion of fossil fuels lead to greenhouse effect.