There is the issue of persistence, but again the potency of chemicals is hugely exaggerated. Ordinary gas clouds typically disperse within minutes. There are longer-lasting agents such as VX, true. These will coat surfaces, remaining deadly to the touch until a few rains have fallen or someone hoses the place down with a solution of bleach. But persistent agents are extremely difficult to vapourise properly. They tend to form a spray of droplets which fall to earth almost at once, like rain.
Improvised protective gear might well get you through a VX attack unharmed, Sean Connery and Nicolas Cage antics in The Rock notwithstanding. Staying indoors would work even better. Once the attack was over, in many cases you'd be able to escape the area with no more than a pair of wellingtons. I'm not saying that a chemical attack would be a completely trivial matter, but it would almost always be preferable to being hit by the same weight of high explosives.
So, if your aim is to kill and injure as many people as possible, you'd be a fool to use chemicals. And yet chemicals are rated as WMDs, while ordinary explosives aren't. So too are biologicals, even more amazingly. Biological "weapons", in the modern sense, have yet to be even demonstrated.
I used to find that strange, as I got into my massive, heavy bomb-disposal armour and walked down a road to check out an ordinary suspicious bag. If it held a few kilos of Semtex, I would be in severe personal danger despite the fact that I was wearing a crippling load of plates and kevlar. On the other hand, I could walk merrily up to a gas shell in lightweight kit and feel almost completely safe (I ought to mention that in my own case there never was any Semtex in the bag. Sandwiches, yes, or shopping; on a couple of mildly sweaty occasions a hoax device. It's remarkable how few genuine bombs there are, outside war zones. You get a special tie if you manage to reach a real one before it goes off).
Back at the dinner table, I sometimes manage to convince people that chemical weapons really aren't as dangerous as ordinary ones – let alone being in the same league as nukes. Saddam Hussein is clearly a bad man, for instance, but his use of chemicals at Halabja and elsewhere doesn't make him significantly badder. Toppling him may or may not have been a good idea, but his possession – or lack of – battlefield chemical weapons shouldn't have affected anyone's thinking on the matter.
At around this stage, the more right-on dinner guests sometimes nod sagely. Evidently the hidden oil-industry puppeteers, or the intelligence agencies, or some other right-wing conspirators are behind this cynical push to demonise mild-mannered Third-World dictators.
But in fact it isn't only sabre-rattling politicians and spooks who stoke the chemical panic. Just about everyone uses the phrase "Weapons of Mass Destruction". Recent examples include the UN, the Lib Dems, Greenpeace, even noted Hollywood liberal George Clooney. All these people and organisations thereby tacitly accept that chemical weapons are equivalent to nukes. It's a foolish, inaccurate habit of thought. We really ought to get away from it, no matter what our politics. ®
Lewis Page did eleven years in the Royal Navy, after brief flirtations with the army and air force. Highlights of his service included Commando training with the Royal Marines, qualification as a mine-clearance diver, and command of a UK-based bomb-disposal team from 2001-04. Apparently they were keeping a few of the best men back to defend Blighty, in case Saddam tried a sneaky counterattack. His book Lions, Donkeys and Dinosaurs: Waste and Blundering in the Armed Forces is out now in paperback. He can occasionally be found on the web at www.lewispage.co.uk