If a visitor to the Nanjing Building in downtown Shanghai opened a window and reached out to take a photograph of the area, security worker Fan Tianyu would receive an immediate alert on a smart bracelet.

He then would rush to the scene of the incident in the seven-story structure, which is nearly 100 years old and stands on the bustling Nanjing Road pedestrian street. Fan would tell the visitor to stop taking photos and close the window.

The bracelet is part of a smart system being used in the building to detect safety risks posed by objects that could fall on crowds of pedestrians below.

The system uses a range of advanced technologies, including big data, artificial intelligence and 5G, and is equipped with multilayer data and internet of things sensing abilities.

It assesses the building for visitor flow, fire prevention, noise levels, use of elevators and escalators, disinfection work and the efficiency of its water pipes.

The system produces reports that are like health checkups for the building around-the-clock.