"New system can shield national relics from damage by pollution. Even the Terracotta Warriors are feeling the effects of China's choking air pollution. Chinese scientists have found that the indoor environment where the Terracotta Warriors are housed could cause them to deteriorate, prompting some scientists to raise the idea of using air curtain technology to help control the environment in the pits."
More at http://www.chinadaily.com.cn/cndy/2013-03/02/content_16268606.htm
Adapted from Wikipedia, courtesy Maros