NYC Releases 170,000 Secret 9/11 Documents Showing Officials Knew Air Was Toxic

A Quarter Century of Silence Broken

For nearly a quarter century, New Yorkers, Ground Zero workers, advocates, and elected officials had called on City Hall to reveal the truth about what it knew about the air quality in downtown Manhattan after the 9/11 attacks. On September 8, that wait ended. New York City released more than 170,000 pages of previously undisclosed records about air quality following the September 11, 2001, attacks, showing city officials at the time knew conditions around Ground Zero were unsafe to breathe despite repeated assurances to the public.

Mayor Zohran Mamdani's administration launched the city's first dedicated 9/11 document portal as part of a settlement resolving two lawsuits brought by the advocacy group 9/11 Health Watch. The initial release includes the frequently cited Harding Memo, records concerning World Trade Center 7, and material from 68 boxes that were not located until 2025 despite multiple Freedom of Information Law requests. The sheer scale of what was hidden — and for how long — is staggering.

What Officials Knew — and When

One undated internal document — a letter to former Mayor Rudy Giuliani's deputy mayor, Robert Harding — listed various potential grounds for lawsuits against the city, including health advisories that caused people to return to the area too soon, causing toxic exposure, rescue workers being provided with faulty equipment, and police failing to secure businesses from looters. Another memo early in the Michael Bloomberg administration, five months after 9/11, said the city was "leaving itself open to a barrage of lawsuits."

The documents contain a fraction of the air quality reports taken at Ground Zero, but they also include crucial internal memos in which officials raised alarms regarding environmental testing between October and November 2001, which regularly detected elevated levels of toxins, including asbestos and hard-to-detect chemicals that were dangerous. Ten months after the terrorist attacks, traces of asbestos were found on the roof of a building located at 15 John Street, less than a mile from where the World Trade Center once stood. The records show that asbestos was detected at some locations at levels below applicable cleanup or exposure benchmarks and at others at levels that appeared to exceed them — and health authorities have said there is no known safe level of asbestos exposure.

The Human Toll the Documents Reveal

Many residents and workers, the documents say, developed "severe, persistent health problems," including chronic nosebleeds, skin rashes, headaches, newly onset asthma, and cough. The impact on children was especially alarming. Researchers found that roughly 25% of kids exposed to 9/11 dust developed asthma, compared with 16% of their peers. Chinese American children who were receiving care in Chinatown showed a "substantial increase in the severity of asthma symptoms," according to one study cited in the documents. The toxins largely came from pulverized building materials and smoldering fires fueled by jet fuel.

Comedian Jon Stewart joined Mayor Mamdani's announcement, shedding new light on the air quality around Ground Zero in the months following the September 11, 2001, terror attacks. Stewart did not mince words. "There was poison in the air, and on the ground, and in the window sills, and in your air conditioners and covering your pets and your clothes, and it stayed there for months. Everyone knew. Now it's very clear that the city knew as well," Stewart said.

What Comes Next for Survivors

"For 25 years, four different Mayoral administrations kept from the public, the U.S. Congress, and the City Council documents showing what the city actually knew about the danger of the toxic chemicals in Lower Manhattan and Western Brooklyn," said Benjamin Chevat, the executive director of 9/11 Health Watch. Mamdani declined to directly blame any of his predecessors, saying he would "leave that to New Yorkers," but said, "administration after administration has ignored those calling for answers and clarity."

The mayor said the city will continue to use its resources to promote two federal programs established under the Zadroga Act: the World Trade Center Health Program and the September 11th Victim Compensation Fund. The records release comes just days before the 25th anniversary of the 9/11 terrorist attacks. As researchers, lawyers, and survivors begin combing through 170,000 pages of long-suppressed truth, the documents may finally give thousands of sick New Yorkers something they have spent decades fighting for — answers, accountability, and perhaps a clearer path to the care they were always owed.