New York City Mayor Zohran Mamdani has released more than 170,000 pages of previously unpublished records that challenge official assurances given after the 11 September 2001 attacks that the air around Ground Zero was safe to breathe. The disclosure, made just days before the 25th anniversary of the attacks that killed 2,977 people, adds to long-standing criticism of the response by federal and city authorities, given that thousands of people exposed to the resulting toxic dust have since died and many more continue to suffer related illnesses.

The documents, found in 68 boxes at the city's Department of Environmental Protection in 2025, include evidence of asbestos contamination well after the attacks, including traces detected on a rooftop near the World Trade Center ten months later and dangerously elevated levels found in carpeting at Stuyvesant High School in August 2002. A February 2002 memo from an adviser to then-mayor Michael Bloomberg is also included, warning that the city faced public relations and legal risks over its handling of indoor air quality and its advice for residents to clean with wet mops and rags. The findings contradict a September 2001 statement by then-EPA Administrator Christine Todd Whitman that monitoring showed the air was safe, with Mamdani saying residents were failed by leaders who told them otherwise.