An assessment of the contribution of air pollution to the weathering of limestone heritage in Malta

Malta's limestone megalithic temples, including those inscribed on the UNESCO World Heritage List, experience weathering primarily influenced by natural climatic factors and sea salt deposition rather than air pollution. A study found that annual stone surface loss due to air pollution is minimal (about one micrometer), overshadowed by variations caused by relative humidity, temperature, wind, rainfall, and ground water replenishment. The research used exposure–response functions from the ICP-materials program to compare atmospheric chemical weathering between urban and rural areas in Malta, evaluating the protective effect of open-sided shelters built over three temples. Findings suggest that while air pollution contributes to deterioration, its impact is less significant than other environmental factors, including salt crystallization events inside and outside shelters.

Grøntoft, T., & Cassar, J. (2020). An assessment of the contribution of air pollution to the weathering of limestone heritage in Malta. Environmental Earth Sciences, 79(12). https://doi.org/10.1007/s12665-020-09027-x