Neighborhoods in Chinese cities Ningbo, Zhengzhou and Tianjin are using “electronic door seals” that alert the police if people under quarantine leave their homes, according to local media reports.
The devices are sensors made by state-owned telecom companies China Mobile and China Telecom, according to Zhejiang Communications Administration and China Telecom. But these sensors reportedly can’t tell why a door might have been opened. When police were alerted about one household breaking quarantine, they learned over a phone call that the residents were just taking out the trash, according to a Zhengzhou newspaper.
The use of door sensors to track people’s whereabouts seems to be growing. In January, a court in Changsha used a different kind of electronic seal to keep someone out of an apartment after she defaulted on her mortgage. That one was also equipped with a camera and sent footage to judges when it detected movement nearby, according to the company that made it.