How does air pollution threaten Athens and its ancient monuments?

Air pollution poses a significant threat to the ancient monuments of Athens, particularly those constructed from marble and limestone, such as the Parthenon and other structures on the Acropolis.123

The primary mechanism of damage is acid deposition. Sulfur dioxide, a common precursor to acid rain, reacts with the calcium carbonate found in these stone materials in the presence of water to form gypsum. This chemical transformation causes the stone surfaces to flake off or dissolve, leading to the gradual degradation of intricate architectural details and sculptures.1

Beyond these chemical reactions, air pollution generally refers to the presence of gases and particulates at levels that cause harm to property and the environment. While the Acropolis has been a UNESCO World Heritage site since 1987 and has undergone extensive restoration efforts to preserve its integrity, the ongoing impact of atmospheric pollutants remains a critical concern for the long-term conservation of these historic sites.43