The air around the statues and monuments in India contains fairly high levels of the oxides of sulphur and nitrogen. This is due to a large number of industries and power plants in the nearby areas. The problem has been further aggravated due to use of poor quality of coal, kerosene and fire wood as fuel for domestic purposes. The states acid rain affects for marble of these statues and monuments.
CaCO3+H2SO4 ‐> CaSO4+H2O+CO2
As a result, this away and marble is getting discoloured and lusterless.