Abstract:
Air pollution, particularly in urban areas, puts human health in danger and has adverse impacts on the built environment. It can
accelerate the natural corrosion rate of cultural heritages and monuments, leading to premature aging and lowering their aesthetic
value. Globally, at the beginning of 2020, to tackle the spread of novel COVID-19, the lockdown was enforced in the most hardhit countries. Therefore, this study assesses, as a first time, the plausible benefits of traffic and urban mobility reductions on the
natural process of deterioration of materials during COVID-19 lockdown in twenty-four major cities on five continents. The
potential risk is estimated based on exceeding the tolerable degradation limits for each material. The notable impact of COVID-19
mobility restrictions on air quality was evidenced in 2020 compared to 2019. The introduced mobility restrictions in 2020 could
decrease the surface recession rate of materials. Extremely randomized trees analysis showed that PM10 was the main influencing
factor for corrosion of portland, copper, cast bronze, and carbon steel with a relative importance of 0.60, 0.32, 0.90, and 0.64,
respectively, while SO2 and HNO3 were mainly responsible for corrosion of sandstone and zinc with a relative importance of
0.60 and 0.40, respectively. The globally adverse governed meteorological conditions in 2020 could not positively influence the
movement restrictions around the world in air quality improvements. Our findings can highlight the need for additional policies
and measures for reducing ambient pollution in cities and the proximity of sensitive cultural heritage to avoid further damage.