Your math is a little off. Your lethal dose is for perfect conditions. Out in the real world the LCt50 (dose required to be lethal for 50% of those exposed) for vaporized Sarin gas is 100mg per m3 (remember it is normally a liquid). The better way to look at is that the amount of Sarin in that artillery shell (assuming prefect dispersal) would kill 50% of all oxygen-breathing organisms (can't forget about the little kitties,too)in a .4 square kilometer area. In an urban setting this would translate into massive causalities. Those not killed would be in severe distress. The ICt50 (dose required to incapacitate 50% of those exposed) is 75mg per m3, and The MCt50 (dose required to produce breath problems) is 3mg per m3.
The 'saving grace' of Sarin is that because of its density it hugs the ground, the LCt 50 for skin exposure is 1.7 g per m3, and it quickly dissipates. That is why chem shells are exploded above ground and it used in barrages rather than as individual shots.
Yeah, I know the math is a little off, but I figure, if the leftist peaceniks used this exact same math for the plutonium dioxide ceramic in the Cassini radioisotope thermal generator in their efforts to block its launch, I might as well use it myself. *grin*
Thanks. As usual around here, someone has answered my question before I've fully formulated it.
Of course, if the political dynamics of this were reversed (if this were, say, a hazmat release and a big bad company could be blamed), the worst case reckoning would be drummed into the public 24/7.