Assessing the Benefit of Air Quality Improvement on Limestone Heritage in China

Atmospheric pollutants can corrode heritage materials, especially for stone, which can cause a great loss that goes far beyond the economic losses of the degraded materials. Over the past decades, conventional air pollutants had been slashed owing to clean air actions in China, which produces a significant co-benefits for heritage conservation. However, the benefits may be offset by increases in the photochemical oxidants in smog, such as ozone, which also damages heritage materials. The study employed the dose-response functions to quantify the impacts of air pollutants on the surface recession of the limestone heritage in China, and assessed the potential benefits of air quality improvement for heritage conservation. The results show that the annual recession rate decreased from 9.69 μmy-1 in 2006 to 6.71μmy-1 in 2020, resulting in a 41.4% increase in the number of heritage sites meeting the ICP Materials (The International Co-operative Program on Effects on Materials including Historic and Cultural Monuments) control target of 8µmy-1 for 2020.The air quality improvement avoided the￥136.2 million cost spent on heritage maintenance. The recession risk showed a distinct regional differences, the southern and northwest regions had been still at a higher material corrosion level than the northern and Qinghai-Tibet regions. In the nationwide, the PM10 is the main risk factor for the surface recession of limestone heritages. The study provides an evidence for the benefits of air quality improvement for heritage conservation. Further, the study also puts forward policy recommendations for heritage conservation, including assessing pollution risk, promoting heritage conservation though social sustainability and implementing differentiated conservation strategies.