In 1979, the USSR had a similar incident at another facility, that resulted in many anthrax deaths downwind. Someone neglected to replace a filter during a routine filter change.
It was rumored to be a strain tailored to kill military-age men, which is why most of the victims were men and few women or children.
I know a guy who lived just half a mile from that place. Near all fatalities were limited to a a nearby barracks of an army motor rifle brigade, a factory and an office building in that very same neighbourhood. One thing all effected buildings had in common is centralized air conditioning. The laboratory was in a rather densely populated suburb with tracts of homes and apartment buildings, at least two schools and day care center. Noone was hurt apart from people in the buildings I said. So maybe centralized AC is not a good thing.