Question

What do you mean by stone cancer? How and why does it occur ?

Answer 1

Sulphur dioxide present in air adversely affects the buildings, sculptures, painted surface, etc., where it causes decolouration and deterioration. The phenomenon is called stone cancer. The marble stones of the TajMahal have developed blackening due to $S{O}_2$ and other pollutants released by the Mathura Refinery.