ugh its Sarin
Just for those that are curious
http://en.wikipedia.org/wiki/Sarin
Sarin is a persistent agent, a tiny quantity on the skin pretty well dooms you unless you have a an atropine injector on hand. You don't need to breath it in to die, you need a vapor droplet on your skin.
On top of that its persistent over weeks. that means that every surface that it touches remains deadly, undersides of boards and fences, hedges etc.
If this is deployed and there's any wind, thousands could die.