Acids have a corrosive effect on limestone or marble buildings
or sculptures. It is well established that either wet or dry
deposition of sulfur dioxide significantly increases the rate
of corrosion on limestone, sandstone, and marble.
sulfur dioxide plus water makes sulfurous acid
SO2 + H2O --> H2SO3
sulfur trioxide plus water makes sulfuric acid
SO3 + H2O --> H2SO4
The sulfuric acid then further reacts with the limestone in
a neutralization reaction.
Limestone: CaCO3 + H2SO4
--> CaSO4 + H2CO3
H2CO3 --> CO2 gas + H2O
The calcium sulfate is soluble in water and hence the limestone
dissolves and crumbles.