IIRC, There was asbestos cladding on some of the structural elements in the towers. It was likely reduced to dust (airborne) and breathed by thousands of New Yorkers when the towers collapsed.
Bad enough we get the aerial effluent from all the major fires in the Pacific Northwest and Western Canada every summer (weeks of red suns at noon and seriously reduced visibility), but there is no way I would have wanted to breathe the dust from the tower collapses.