...for spreading panic. Is there any mileage in this? I suppose it's too hard to legislate for sanity given the abuses to which such legislation could be subject.

Bit insensitive those closing comments. Even an attack harming 12 people is of concern and it is right that the authorities are carrying out experiments to get a better understanding of any threat such as this. I wonder if the author lives and works in London or not.

'Real pros like the IRA" and the rise in Islamic fundamentalist terrorism is that the IRA used to helpfully phone someone up and actually tell them when and where a bomb was due to go off. The 7/7 bombings make IRA activity in London seem almost nostalgic.

Oh yes, here we are 'A Higher from of Killing' by Robert Harris and Jeremy Paxman.

i950 - San Francisco was dosed with Bacillus globigii and Serratia marcescens to simulate a Soviet biological attack. Both bacteria were 'thought' to be harmless. Later tests showed that pretty much everyone in SF had inhaled the bacteria.

The next year, the Navy contaminated wooden crates in Pennsylvania then had them shipped to Norfolk VA. This time they included Aspergillus fumigatis because (and you're going to love this one) it was thought that black workers were more likely to host the bacterium.

1953, not just the East Coast of the US, but also Winnipeg - Canada, whose populaiton were told that the city was being sprayed with experimental chemicals that could hide it from radar. That test was repeated (with the same excuse) on Minneapolis.

Meanwhile back in Blighty, in 1952 and 1953, HMS Ben Lomand was dispatched to the West Coast of Scotland where it dispersed clouds of active disease-causing bacteria over rafts holding animals. Later trials were only cancelled because of bad weather. The tests were then repeated in the calmer weather of the Bahamas until 1955.

And from 1957 onwards, the RAF was busy flying round the coast spraying the supposedly harmless, but very easy to detect zinc cadmium sulphate from drop tanks. Pretty much the whole country was dosed with the stuff. Further clouds of zcs were also released from the chimneys of Harwell nuclear research station.

The end result of all this work? That it's pretty much impossible to stop people being exposed to some amount of contamination, but that the number actually exposed to deadly quantities is relatively small.

So what's changed? Ah yes, now we can expect lots of official Home Office footage of scary looking armed police in NBC suits; that'll teach us to doubt John Reid!

the wind is stronger and blowing in a different direction if and when such an attack occurs. I cannot see six weeks of trials covering all possible atmospheric conditions.

Of course the climate of fear generated by such actions makes it easier to curb our freedom.

However, not being prepared for such an eventuality would be gross negligence. After all we have upset a lot of people and created more enemies than we ever had before by bending over for the Bush administration.

Perhaps a policy change that curbs American imperialism in the middle east would be a more akin to dealing with the disease rather than preparing for the symptoms.

"Making prompt, accurate information available to the public could prevent the panic sought by terrorists."

Is this the kind of prompt & accurate information available to the public during 7/7? Or the Menezes shooting? Or the raid in North London where the guy was shot in the stomach? Or ...

This kind of information certainly stops me panicking!

Isn't gas and dust-plume modelling sufficiently good these days that there isn't much point doing real-world trials unless either the public publicity of doing so is what's really being looked for, or it helps to impress the political paymasters?

To Chris Matchett

How are you supposed to make a comparison of the deadliness of two forms of attack without comparing fatalities of historical events?

It is not insensitive but merely dispassionate, please learn the difference.

Yeah Dan,

Every IRA bomb was preceided by a very accurate warning of where the so called devices where placed.

Having survived the IRAs mischief (may as well downplay anything that didn't involve the London area). It was common practice to lie about locations or give warnings much too late to be useful. The lies where useful in having people security forces moving into closer to the real bomb. This happend to me on 3 separate occasions.

I point you to this as an oft forgotten piece of nostalga for the good old days

http://cain.ulst.ac.uk/events/bfriday/nio/nio72.htm which was etched on my then 9 year old mind

As for the bullsh1t regarding this test, how long till there an announcement wtating, "oops after further research the afent we release is toxic, sorry about that"

Fluid flow is extremely complex, even in something like a 2 foot long hose. To accurately model an entire region would not only take many many man hours to program, but an intense amount of cpu time to run. for arrucacy you'd probably need an element size of around .5 meters - consider how many of those it'd take to cover London and the surrounding areas. Then you have to accurately know the boundary conditions (incoming wind speeds at every point on the perimiter of the simulation.)

Even then, any computer model has to be validated with real world tests.

With a situation so complex, it is likely that any attempt to model it would just come out with garbage, and lots of wasted time and money.

- Nexox

After the post 9/11 anthrax scare int eh USA, someone in one of teh major news companies commented that if someone were to spray a sporrts stadium with water from a crop duster, the panic alone could kill a large number of people and cause a huge amount of chaos.

Correct, anyone who has never been a victim of terrorism, IRA or otherwise has no right to air a comment.

It may be easier to use explosive than the more complex dirty bomb attacks but the only result needed is media coverage and that cost serious money. Probably serval million per hour on the cheaper channels, but even more for talking point and newspaper coverage.

So it is easier to blow up some home made explosive but if you want even more coverage you need a gas or radioactive angle, although it does seem close at the moment in media returns I think Iraq is an example of the lowering value of blowing yourself up. I harldy notice unless it's in the 30+ range (in a single attack of course) and the bbc don't report the under 12 dead anymore.

So yeah you need dirty bombs or something to get the media back.

"not being prepared for such an eventuality would be gross negligence."

Not true: not doing a risk analysis of the suggested threat would be gross negligence.

Not preparing for an eventuality that you've determined not to be a threat is just like leaving your tinfoil hat at home or not buying that asteroid shield for the croquet lawn: a simple balance of percieved threat against the available resources and egreigousness of the protection.