Bronze sculptures, renowned for their durability and artistic value, face unique challenges in environments with high sulfur dioxide (SO₂) concentrations. This gas, commonly emitted by industrial activities and urban pollution, reacts with bronze to form a surface layer of copper sulfate and other compounds. While this process initially causes discoloration, it often leads to the development of a protective patina—a naturally occurring oxide layer that shields the underlying metal from further degradation.

The alloy composition of bronze (typically copper and tin) enhances its resistance to SO₂-induced corrosion. Over time, the patina evolves into a stable greenish-blue hue, which many artists and conservators consider aesthetically desirable. However, in extreme cases, prolonged exposure may accelerate structural weakening, particularly in outdoor sculptures exposed to acid rain.

To mitigate damage, experts recommend regular maintenance, including gentle cleaning and protective wax coatings. Modern bronze alloys with added elements like phosphorus or aluminum further improve sulfur dioxide resistance. Understanding these interactions helps conservators preserve bronze artworks in urban or industrial settings while maintaining their historical and artistic integrity.