> Then again there are well practiced methods for removing sources of similarly hazardous air-bourn particulates such as asbestos, i'm not sure how much difference there is between the two beyond the low risk of pure exposure (inhalation being the serious risk here).

There's also the difference that this is a U-Bahn station in use, in the rough middle of a line. Closing it down for a prolonged period of time, and fully sealing it from the rest of the line to avoid the spread of dust through the metro tunnels would be a significant and disruptive undertaking.