What a full body scanner is

One technology used under the name “full-body scanner” is the millimeter wave scanner, the active form of which reflects extremely high frequency radio waves off the body to make an image on which one can see some types of objects hidden under the clothes. Passive millimeter wave screening devices rely on only the raw energy […]

One technology used under the name “full-body scanner” is the millimeter wave scanner, the active form of which reflects extremely high frequency radio waves off the body to make an image on which one can see some types of objects hidden under the clothes.

Passive millimeter wave screening devices rely on only the raw energy that is naturally emitted from the human body or objects concealed on the body; passive devices do not transmit millimeter waves. Another technology in use is the backscatter X-ray.

Two advantages of full-body scanners over a physical strip search are that it is quicker (takes only 15 seconds) and that people do not have to physically remove their clothes.

A disadvantage is that the scanners are being used to perform routine, virtual strip searches without probable cause which opponents claim are illegal unreasonable searches that violate basic human rights.

Furthermore, the true long-term health effects of the active, radiating technologies are unknown. Passive millimeter wave screening is marketed as safe because its technology does not require radiating the subject with specific wavelengths.

Source: Wikipedia