We probably have passed each other on the street.

I remember the clouds on 9-11 well. I was on the phone at the time with my them girlfriend, and she was urging me to leave my office. I am very glad I did not. Many that I know did ended up covered by and enclosed within the cloud. My building was in the cloud, but not much came into our office. Didn't have a mask, but I walked out about 4:30 with a wet t-shirt over my face. That was an unforgettable walk.

I tend to think that potential chemical and biological attacks would be of such a nature that the agents could not travel very far. So long as you were not very close, staying put as I did on 9-11 would probably be a good move. Still, I feel better knowing my wife has a hood. I cannot count on her thinking calmly and makign the right decision, especially if there is a crowd making a wrong decision.