It is possible that the “black stuff” was asbestos but I would characterize your exposure as very minimal and the risk very slight, assuming that you avoided proximity to the material to the extent that you did not breathe-in fibers, if they were present and you made no bodily contact with it. Should this not allay your concern completely, it would be reasonable for you to request an official report on the nature of this material, from the building Manager or the Royal Bank and, were you unsatisfied with their response, to report this incident to the Vancouver or BC Department of Public Health.
Good luck
Dear Dr. Tinkelman,
Thank you very much for your reply and suggestions.
John