A large numbers of industris and power plants are around near the area of Taj Mahal. Which uses poor quality of coal, kerosene and firewood because of this the air around the Taj Mahal contains fairly high level of sulphur and nitrogen oxides. This resulting in acid rain which reacts with marble of Taj Mahal.

$\mathrm{CaCO}_{3}+\mathrm{H}_{2} \mathrm{SO}_{4} \rightarrow \mathrm{CaSO}_{4}+\mathrm{H}_{2} \mathrm{O}+\mathrm{CO}_{2}$

Thus, this wonderful monument that has attracted people from around the world. As a result, the monument is being slowly disfigured and the marble is getting discoloured and lustreless.