Some public transportation systems, including Los Angeles County Metropolitan Transportation Authority, plan to use terahertz millimeter-wave screening devices that can screen passengers for explosives and weapons from up to 30 feet away.
The devices detect body heat and show images of anything blocking heat — such as guns and suicide vests. If a passenger’s image displays something suspicious – a dark mass around the waist, for instance, a bomb-sniffing K9 would go by the passenger to check. If the dog detects nothing, the passenger would be free to proceed.
Groups such as the American Civil Liberties Union have expressed concerns about how the devices would be used and asked how the scanners could expose people of color to unfair searches.
Wendy M. Grossman asked a variety of security experts for their opinions about terahertz millimeter-wave screening for Scientific American.
