In terms of the potential for economic damage, a full-fledged bioweapon attack is not all that much more effective than a low-sophistication attack (or several, staged at the same time). So while it is useful to understand the way subway systems may disperse particles, this kind of research does not reduce the risk of economic damage from low-sophistication attacks targeted at the subway system. It is difficult to ob…
Obviously there are cheaper ways to cause more expensive damage. That's not what terrorists care about and that's not what potential victims of terrorism care about.