Quantifying the Potential Co-Benefit of Air Quality Improvement on Cultural Heritage in China

Abstract

Atmospheric pollutants can corrode heritage materials, especially 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 have been slashed owing to clean air actions in China, which produces a significant co-benefit for heritage conservation. However, the benefits may be offset by increases in the photochemical oxidants in smog, such as ozone, which damage heritage materials. This study employed dose–response functions to quantify the impacts of air pollutants on the surface recession of the limestone of heritage structures 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 6.71 μmy−1 in 2020, resulting in a 41.4% increase in the number of heritage sites meeting the ICP Materials (International Co-operative Program on Effects on Materials including Historic and Cultural Monuments) control target of 8 µmy−1 for 2020. The air quality improvement avoided CNY 136.2 million in heritage site maintenance costs. The recession risk shows distinct regional differences; the southern and northwest regions are still at a higher material corrosion level than the northern and Qinghai–Tibet regions. Nationwide, PM10 (particles with aerodynamic diameter less than 10 μm) is the main risk factor responsible for the surface recession of limestone material of heritage structures in China. The study provides 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 through social sustainability, and implementing differentiated conservation strategies.