I had to look it up!
A vesicant is a drug or other agent that produces blisters.
Vesicants include mustard gas, phosgene oxime and lewisite. Comparing the available symptoms listed from the reporter that callapsed, lewisite was the best match. The itching, blanching and collapse (possibly from hypotension) were the key discriminators.
http://www.freerepublic.com/focus/f-news/1144246/posts
Good FR terror post.
Pay special attention to "oil refineries." [We haven't built one since 70's and if we lose even one or two, it would shut things down..for a loooong time]
The lack of refining capacity...this is treason on the part of those who opposed this over the years.