New York City Mayor Zohran Mamdani has released around 170,000 documents showing that officials had internal concerns about air quality in Manhattan shortly after the 11 September 2001 attacks, even as the public was repeatedly told the air was safe to breathe. Mamdani said the papers reveal asbestos was found "nearly everywhere" tested near Ground Zero, and accused past administrations of misleading residents and workers about the dangers, with illnesses linked to the toxic dust having since killed more people than the attacks themselves. The release settles a lawsuit brought by advocacy group 9/11 Health Watch and follows years of pressure from survivors for greater transparency.

The documents, published via an online portal to coincide with the 25th anniversary of the attacks, cost the city more than $34m (£25m) to compile after 68 boxes were discovered last year having previously been said not to exist; further material is due to be released over the coming year. Among the files is the "Harding Memo" from October 2001, warning a deputy mayor under Rudy Giuliani that the city could face up to 35,000 legal claims over its handling of the disaster. Days after the attacks, city and federal agencies including the EPA had declared the air safe, a claim the EPA's then-head later apologised for; survivors, including former FDNY responders, have long said they knew at the time that the air felt toxic.