What role does humidity play in the preservation of outdoor marble sculptures?

Humidity plays a dual role in the preservation of outdoor marble sculptures, acting as both a destructive force and an environmental factor that requires careful management. High humidity accelerates chemical erosion through acid rain formation and promotes the growth of algae, lichen, and moss which secrete damaging acids. Conversely, extremely dry conditions can cause micro-cracking. Optimal preservation occurs when relative humidity remains stable between 40-60%, minimizing thermal expansion and contraction. Modern conservation techniques include breathable protective coatings and environmental shelters that mitigate humidity's harmful effects while allowing natural ventilation. Regular monitoring using humidity sensors helps conservators implement timely interventions to prevent irreversible damage to these cultural artifacts.