By Rob Coppinger in London

Explosive chemicals can be detected through techniques known as bulk and trace detection - X-rays and electronic noses, respectively - that identify molecules from a compound's vapour around its container or handler.

X-ray machines can indicate the presence of organic, carbon-based compounds. Methyl nitrate is a liquid explosive and it is carbon based. Electronic noses can be handheld or large box units, called trace portals, which can analyse the air immediately around a person. They are in use at over 30 US airports and two have recently been installed at UK airports.

US company DefenderTech International Solutions is offering Protadas, a millimetre-wave camera that detects energy given off by all things, living and inanimate, at terahertz wavelengths. This technique can detect hidden non-metallic materials.

While X-ray machines with various levels of capability are operational, there is no guarantee that every Western airport's X-ray machines are capable of detecting explosives and a majority of major airports do not have the trace portals, which have until recently been on trial. But it could take years and a lot of investment before there is a comprehensive array of bulk and trace technique detection technologies in place to check all baggage and passengers.

Source: Flight International