Home Office counter-terror boffins from the chemical, biological, radiological, and nuclear (CBRN) Science and Technology Programme will carry out "tracer gas trials" in London starting this weekend.
Tony McNulty, the minister in charge of security spooks and special-powers cops, revealed the plans to Parliament yesterday.
"The trials will improve our understanding of the movement of air-borne material in the urban environment and will enable enhancements in public protection to be developed," he said.
"It will improve the UK's ability to deal with the consequences of a CBRN release."
The trials will involve the release of small amounts of "non-toxic, odourless gases" in the Marylebone area starting on Sunday, and will run for a four to six week period. The Press Association reports that about 20 scientific monitoring stations will be set up in the area.
The government terrorist-busting eggheads will use the data gleaned from the trials to develop computer models of dirty-bomb or urban chemical-weapons attacks. These are expected to form part of security plans for the 2012 Olympics, perhaps even feeding into the design and location of sports facilities.
Mr McNulty also revealed that similar tracer trials have already taken place in the London Underground during March and April.
Even so, it could be that if you build it (a big CBRN-response organisation) the dirty-bomb and chemical weapons terrorists may not come. Not if they know what they're doing, anyway.
The US Nuclear Regulatory Commission says that: "Most [dirty bombs] would not release enough radiation to kill people or cause severe illness - the conventional explosive itself would be more harmful to individuals than the radioactive material. However, depending on the scenario, a [dirty bomb] explosion could create fear and panic. Making prompt, accurate information available to the public could prevent the panic sought by terrorists.
"Immediate health effects from exposure to the low radiation levels expected from a [dirty bomb] would likely be minimal."
As ever, plain old explosives are the big worry. As for chemicals, compare the effects of the Tokyo subway gas attack (10 terrorists, five attacks each involving 1kg of hard-to-get sarin nerve gas, 12 dead total) with a typical backpack-bomb attack (London 7/7: four terrorists, four simple home made devices, 52 dead). Only a stupid attacker would bother with chemicals. Real pros like the IRA, for instance, never have.
Still, nobody ever made a mistake over-estimating the ability of Western citizens and in particular their media to get in a panic. ®