@anemone @mian The twin towers did in fact use asbestos and them collapsing released ~400 tons of pulverized asbestos.

The WTC7 did not use asbestos fireproofing - instead it used gypsum-based Monokote spray-on fireproofing for structural steel elements.

Monokote has a two-hour fire rating for steel beams, girders, and trusses, and a three-hour rating for columns, while the WTC7 burned for 7 hours before collapsing - maybe if it had used more heat-resistant asbestos for fireproofing it wouldn't have collapsed.