The Chinese government has launched a massive crackdown on prostitution in Dongguan, a well-known sex industry hub in southern China.
In addition to a news feature  on China Central Television about the corruption of the sex industry in Dongguan, the official Sina Weibo published an eight-hour population in-flow and out-flow map of Donguan city, which has been interpreted as the escape path of “prostitutes” and “prostitution clients” during the crackdown. Generated by Baidu Qianxi  with data from Baidu map, the map indicated that most people fleeing the crackdown “escaped” to Hong Kong.
Originally, Baidu Qianxi was designed as a visualization tool that could map population flows during the Chinese Lunar New Year. But as Luo Changping at Letscorp pointed out  [zh], the fact that Baidu Qianxi was able to appropriate the data surrounding the prostitution crackdown suggests that authorities are using mass surveillance to track these patterns, rather than only targeting criminal suspects, and thereby violating the personal privacy of untold numbers of citizens.
Some technology bloggers such as Lui Xuewen noted  that the so-called “escape route” shown on the map was highly misleading as there were other reasons behind the population flow. In fact, in an ordinary day, population flow between the two cities can even be higher as many factories in Dongguan are owned by people from Hong Kong.
The use of geolocation tracking technology in this crackdown by the party propaganda authority indicates to the public that the police authority, through Baidu and other mobile application developers, is capable of tracking mobile phones and thus the real identity of individuals, as nearly all mobile numbers are linked with the owner's identity card. In reaction to this threat, many Hong Kong netizens said that they planned to shut down their mobile when traveling in China.