[kms61]

The terrorists in this incident had gas masks (called "respirators" by the news reports, but I assume they were gas masks). But they would have had to wear the masks 24 hours a day for the duration, and even then it may not have helped, as I suspect this stuff may be absorbed through skin contact.

[strela]

The terrorists in this incident had gas masks (called "respirators" by the news reports, but I assume they were gas masks).

You're likely right. Something like a Scott Air Pack respirator that firefighters use would likely be too heavy, expensive, and cumbersome for terrorists.