[Kelly_2000]

"We're not talking about trace amounts here. We're talking about enough to make a bomb. "

It doesn't matter a device that allows people to shuffle through an arch that looks for semtex, C4, nitro, chemical or incendiary bombs, biological etc does not exist.

[null and void]

Actually, there are sniffers that can and do detect vapors from explosives.

Google it and see...