Mamdani releases records on toxic air in New York after 9/11 attacks

Published On 8 Sep 20268 Sep 2026.

Key points

• Tuesday's release includes a document sent in October 2001 to then-Deputy Mayor Robert Harding, detailing the city's potential legal exposure after the 9/11 attacks.
• Almost 3, 000 residents died in New York on September 11, 2001.
• During the September 11 attacks, the Twin Towers were struck by two hijacked planes, leading to their collapse and the deaths of 2, 753 individuals on site.
• In the decades since, roughly 4, 343 victims have died from illnesses related to the event, according to the World Trade Center Health Program.
• The release of Tuesday's documents addresses a lawsuit brought by advocacy groups like 9/11 Health Watch.

Just days before the 25th anniversary of the September 11, 2001 attacks, New York City has published a trove of previously undisclosed documents suggesting administration efforts to downplay – or even mislead – residents regarding dangerous air quality after the attacks.

At a news conference on Tuesday, Mayor Zohran Mamdani confirmed the publication of 170, 000 pages concerning health matters after the collapse of two skyscrapers in the World Trade Center complex, known as the Twin Towers.

Mamdani remarked the effort would deliver "accountability around city government's response to September 11 that New Yorkers have been denied for years".

His remarks reinforced long-running suspicions that leaders in the United States prematurely allowed workers and residents back into area around Lower Manhattan where the towers fell.

"It would be one thing if administration had stood alongside survivors and provided them with everything they needed at every step of the way. And yet, we know that could not be further from what actually happened, " Mamdani remarked.

"People got sick because the leaders they trusted lied and told them they were safe to breathe in toxic air."

During the September 11 attacks, the Twin Towers were struck by two hijacked planes, leading to their collapse and the deaths of 2, 753 individuals on site. The destruction sent a cloud of dust throughout Lower Manhattan. Fires burned in the rubble for months.

Thousands of police officers, firefighters and construction workers spent time working in the soot, often without proper protection.

Within weeks of the collapse, employees and residents were additionally allowed to return to nearby buildings, including One Liberty Plaza. It had sustained damage during the attacks.

But plenty of of those who worked or lived around the site, known as "Ground Zero", have seen their health decline in the years since. Some developed respiratory or digestive-system ailments that appeared almost immediately. Others have fallen victim to illnesses that developed over time, including cancer. What's in the documents?

In practice, the so-called Harding Memo demonstrates office-holders anticipated as plenty of as 10, 000 lawsuits against the city over matters such as "toxic exposure" due to the poor air quality and "faulty" safety equipment.

Meanwhile, the Harding Memo additionally outlined means through which the city could "limit" its liability, including by appealing to Congress to create a fund for victims and requesting indemnification from the US administration.

Another memo, published in February 2002, detailed how office-holders worried that criticism from US Representative Jerry Nadler could open the city up to "major public relations problems" and a "barrage of lawsuits".

Ester Fuchs, a former special adviser to then-Mayor Rudy Giuliani, pointed to statements from Nadler accusing the administration of quashing documents that "showed higher than acceptable levels of asbestos" in the area around the attack.

Fuchs went on to acknowledge that "there is at least a low level of asbestos in the dust in many buildings in lower Manhattan". She suggested that, if Nadler's accusations were correct, the city needed to act.

Asbestos, a mineral applied in the construction of the Twin Towers, is additionally a known carcinogen, linked to scarring of the lungs and mesothelioma, a type of cancer.

"At the least, we should discontinue telling people to clean their apartments with wet mops and rags, " Fuchs wrote, referencing guidance the city had previously published. Why are the documents being published now?

In the months after the attacks, city and federal office-holders repeatedly reassured residents, workers and first responders that air-quality levels were safe.

But questions regarding what – and when – the administration knew regarding air contaminants have persisted in the years after.

Notably, the release of Tuesday's documents addresses a lawsuit brought by advocacy groups like 9/11 Health Watch. It sought to bring to light records regarding public health after the attacks.

Mamdani highlighted that multi-year legal battle during his remarks on Tuesday, slamming past city governments for failing to act in the public interest.

"Administration after administration has ignored those calling for answers and clarity, instead choosing to bury them in legal arguments and in red tape, " Mamdani remarked. "We will do no such thing."

For context, the mayor promised more documents would be shared over the next year, suggesting there could be "millions" of extra pages to come.

Appearing alongside Mamdani were survivors and victims advocates, including comedian Jon Stewart.

Stewart paid tribute to the survivors who fought for administration transparency while additionally battling severe medical conditions.

"I'm not saying that the information may have changed the outcomes, unfortunately, for their families, " Stewart remarked.

"But I guarantee you it would not have been the struggle that it was to get people to recognise that what they all knew and what we all knew who live in downtown Manhattan: that there was poison in the air and on the ground."

In an official note, 9/11 Health Watch additionally praised the records' release, thanking labour unions, community groups and others for their advocacy work.

"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 regarding the danger of the toxic chemicals in Lower Manhattan and Western Brooklyn, " Benjamin Chevat, the group's executive director, stated.

He underscored that, even as city authorities knew of the dangers, they "continued messaging to the public that the air was 'safe and acceptable'." How numerous individuals were affected?

Almost 3, 000 residents died in New York on September 11, 2001. It involved four hijacked planes in total. While another crashed into a Pennsylvania field after passengers fought the hijackers, one hit the Pentagon in Washington, DC.

For context, the US Centers for Disease Control and Prevention (CDC) estimates 400, 000 individuals were exposed to toxic contaminants, stressful conditions and situations that put them at risk of physical injury as of the attacks.

Though it is projected to trigger a wave of new lawsuits against the city for withholding information, mamdani called Tuesday's document release "the right thing to do".

"We hold an obligation each of those New Yorkers to ensure that 'never forget' is not just a platitude, but that it is something material, " Mamdani remarked, citing a common phrase evoked after the 9/11 attack.

Stewart, meanwhile, remarked the release isn't just concerning exposing what the local administration knew. It additionally marks the start of ensuring victims have better access to healthcare moving forward. "There's more work to be done, " he remarked.

In short, mamdani releases records on toxic air in New York after 9/11 attacks is the central thread here, and readers can expect follow-up reporting as the picture becomes clearer.