China’s Terracotta Warrior Army Is Deteriorating

China’s famed terracota army, which consists of more than 8,000 life-size soldiers, 130 chariots with 520 horses and 150 cavalry horses made out of terracota clay, may eventually turn into piles of dust if the country doesn’t take steps to better preserve the relics, says a paper published in Environmental Science and Technology.

The army, which was part of an emperor’s funerary procession around 209 B.C., was discovered in 1974 by some local farmers digging in their fields. In 1979, China set up a vast museum to hold the treasures. The mausoleum was declared a UNESCO World Heritage site, and more than 5 million visitors walk among the warriors per year.

But researchers worry that environmental control systems used in the terracotta warrior’s museum (and in other archaeology museums in China) is slowly ruining these treasures. Environments like this one, often designed for visitor comfort rather than the well-being of artifacts, can be detrimental to the conservation of the museum’s holdings.

Some of the soldiers, the authors write, have already begun showing signs of wear and deterioration since they were first unearthed and put on display. In an analysis of air pollutants affecting the soldiers, the researchers found notable concentrations of sulfur dioxide, nitrogen oxide, nitrogen dioxide and ozone. The levels the researchers recorded exceeded those typically reported each year by the museum. Some of the pollutants could be wafting in from a nearby thermal power plant, they hypothesized.

Currently, the artifacts are held in a large open space. The researchers point out the difficulty of maintaining specific temperatures, humidity levels and airflows in such a big area, and they suggest some possible fixes. Recreating the pit-like environment where the warriors were first found and which preserved them intact for so many years may be the best solution. The exhibition pit’s temperature and humidity would reflect the conditions under which the army was first discovered. Visitors could still tour these semi-exposed pits, but their presence would not cause the same impact as it seems to today.

More than fifty archeology museums are currently under construction in China, and the authors hope curators take relic preservation into serious consideration. They conclude:

Archeology museums have the responsibility of preserving and exhibiting the cultural inheritance of our ancient civilization.

The challenge for the archeology museums is to produce an appropriate environmental control to ensure long-term preservation of relics within the premise that could also maintain the panorama view of the excavation sites.

More from Smithsonian.com:

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Rachel Nuwer is a freelance science writer based in Brooklyn.