Mamdani says 9/11 records show authorities knew about toxic air at Ground Zero

New York City Mayor Zohran Mamdani announced the release of more than 170,000 pages of municipal records related to the September 11, 2001, terrorist attacks, saying the documents show that city and federal authorities knew the air around Ground Zero was contaminated while the public was being told it was safe.

The records were released just days before the 25th anniversary of the attacks. Mamdani made the announcement Tuesday at City Hall alongside public officials, first responders, survivors and community activists.

According to Mamdani, early environmental testing detected hazardous particles “almost everywhere” authorities examined at Ground Zero. Despite those findings, public messages from New York City and the U.S. Environmental Protection Agency told residents, workers and students that they could return to the area.

“The people got sick because the leaders they trusted lied to them and told them it was safe to breathe toxic air,” Mamdani said during the news conference.

The mayor said the human cost of the decisions made after the attacks has continued to grow. More than 9,000 people have died from illnesses related to 9/11, nearly three times the number of people who were killed on the day of the attacks, according to the information presented by the mayor.

Among the documents highlighted by Mamdani is an October 2001 memo known as the “Harding memo,” which was sent to then-Deputy Mayor Robert Harding during the administration of Mayor Rudy Giuliani. The memo warned that the city could face as many as 35,000 lawsuits over its handling of the response to the attacks.

The document also specifically raised the possibility of legal liability stemming from health advisories that encouraged people to return to the area too soon, potentially exposing them to toxic substances.

The records were among 68 boxes of documents that were only recently located. Mamdani said the release is part of a broader effort to make the city’s response to 9/11 more transparent.

The mayor’s administration also plans to release additional records over the coming months through a dedicated public website. The city’s first budget includes $34 million for a public portal documenting the municipal response to 9/11, as well as specialized staff to help victims seek assistance from available funds.

According to the administration, personal identifying information and security assessments involving Lower Manhattan buildings will be withheld, but other records will be made available.