China is deploying its mass surveillance system in an effort to combat the spread of the coronavirus.

As millions return to major cities and resume work, they will be subject to unprecedented monitoring.

New facial recognition and temperature scanning technology have been installed in public transport systems.

The government says it is being used to keep everyone safe.

But concerns are growing over the "big brother" use of data, giving police the power to create a digital authoritarian state.

Al Jazeera's Katrina Yu reports from Zhengzhou, China.