CHICAGO — This week, Metra is testing new security technology with the TSA at several of its downtown Chicago stations.

Metra said it’s a new type of “passive screening technology” used to detect potential threats, like explosive devices, that could be concealed under clothes.

It does not take photos or videos and does not emit radiation or show anatomical details of a person.

Metra said this was not in response to any specific threat, but is party of a nationwide effort to determine whether this type of technology can help safeguard against terrorist threats in mass transit.

Riders will see it at the Van Buren Station Wednesday and at Ogilvie Thursday. It was at Millennium Station Tuesday.

Metra said it’s too early to say if the screenings will ever be implemented permanently.