According to the Environmental Protection Agency, “acid rain" refers to a mixture of wet and dry deposition (deposited material) from the atmosphere containing higher than normal amounts of nitric and sulfuric acids. Apart from its adverse effects on the ecosystem, acid rain degrades stone monuments, especially those built out of limestone or marble.
Fading and tarnishing of color are the most common effects of acid rain. The milky white marble of the Taj Mahal in India is turning pale.
Acid rain causes pock marks in various marble structures, thereby marring their appearance. The marble columns of the Capitol building in Washington D.C have developed such pock marks.
Disintegration of Parts
As a result of exposure to acid rain, parts of several monuments are falling off. Some of the pieces of the Acropolis of Athens, Greece have begun falling off and a total structural collapse is possible in future.
Sometimes the damage of acid rain on monuments is irreversible. Acid rain is erasing most of the art in the Dampier rock art complex in Australia, and it is estimated that by the middle of the 21st century, most of this art will disappear completely.
Continuous erosion of monuments from acid rain is a global problem. In order to preserve these heritage sites, governments spend huge sums of money on their renovation.