Acid rain is a major threat to the beauty of the Taj Mahal. Taj Mahal is made up of marble. When acid rains fall on the monument made of marble, they react with marble to form a powder-like substance that is then washed away by the rain. This phenomenon is known as marble cancer. Also, the soot particles emitted from the Mathura oil refinery located near Agra is leading to the yellowing of the marble of Taj Mahal.

The images show the yellowing effect on the marbles of The Taj Mahal.