1. If we consider Taj Mahal, the industries located in and around Agra like rubber processing, automobile, chemicals and especially the Mathura oil refinery, have been responsible for producing pollutants like sulphur dioxide and nitrogen dioxide.
2. These gases react with the water vapour present in the atmosphere to form sulphuric acid and nitric acid.
3. The acids drop down with rain, making the rain acidic. This is called acid rain.
4. Acid rain corrodes the marble of the monument.
5.The phenomenon is also called “Marble cancer”.