The administrators of ancient Buddhist grottoes in northwest China\'s Gansu Province hope that newly-installed sensors will help protect the caves by allowing subtle environmental changes to be monitored. The devices will start monitoring changes in temperature, humidity, carbon dioxide density and other conditions in the Bingling Temple Grottoes near Yongjing County this month, said Shi Jingsong, head of an institute in charge of protecting the grottoes. \"The data will help us analyze the impact of visitors and weather on the caves\' environment,\" Shi said, adding that precautionary measures that are implemented based on the data will help protect the relics from potential damage. Twenty of the temple\'s 183 caves will be monitored, Shi said. Initially built in 420 BC, the Bingling Temple Grottoes are known for their large number of Buddhist statues, stupas and murals. The government is working to set up monitoring and early warning systems at heritage sites along the Silk Road in order to better protect the sites and prepare them for application to the World Heritage List this year. The construction of monitoring systems has been launched in other sites along the ancient trade route, including the Maijishan Grottoes and Yumenguan Site, said Xiao Xuezhi, vice head of the Gansu Provincial Bureau of Cultural Heritage.