Mayor Zohran Mamdani announced on September 12, 2026 that the city administration has released a collection of air‑quality monitoring data from Lower Manhattan that has been kept from public view for 25 years. The records cover the period following the September 11, 2001 attacks and are now accessible to the public, survivors of the attacks and advocacy groups.
The newly released files contain measurements taken in the wake of the attacks at locations that include offices, residential buildings and schools throughout Lower Manhattan. The data were gathered by city monitors that tracked pollutants and particulate matter in the immediate aftermath of the disaster. The release makes these observations available for review and analysis for the first time.
Survivors and environmental advocates have welcomed the publication, noting that the information can help answer long‑standing questions about the conditions in which residents, workers and students lived and worked after the towers collapsed. The city’s decision to make the data public responds to calls from those groups for greater transparency regarding the health impacts of the dust and fumes generated by the attacks.
Since 2001, concerns about toxic dust and air quality in the affected area have persisted, with many individuals seeking clearer evidence of exposure levels. Although monitoring had been conducted continuously, the results had not been released to the public until now. The mayor’s office cited the need to address these ongoing concerns as the primary reason for the disclosure.
The release of the air‑quality records marks a milestone in the city’s effort to document the environmental aftermath of the September 11 attacks. It provides a factual basis for evaluating health outcomes and for future reference in emergency response planning.