Mayor Zohran Mamdani announced this week that New York City has made public a set of air‑quality monitoring records that were collected in Lower Manhattan following the September 11, 2001 attacks. The data, which had not been released previously, were issued by the city administration during the week of September 7‑13, 2026, marking the first disclosure of the information after a quarter‑century.
The released documents contain measurements taken in the immediate aftermath of the attacks, documenting levels of dust, pollutants, and other airborne substances in the affected area. The city said the files were compiled by municipal agencies tasked with environmental monitoring at the time and have now been uploaded to an online portal for public access.
Survivors of the attacks and advocacy groups have welcomed the release, noting that the information addresses questions that have persisted since the disaster. The records are expected to provide details that can help individuals assess the conditions they experienced while working, living, or attending school in Lower Manhattan during the recovery period.
Since the attacks, residents, office workers, and students returned to buildings and neighborhoods throughout Lower Manhattan despite ongoing concerns about air quality. The presence of dust and other contaminants was a source of uncertainty for many, and the lack of publicly available data contributed to the uncertainty.
The city administration indicated that making the monitoring data available is intended to contribute to a fuller understanding of the environmental impact of the September 11 events. Officials said the release aligns with efforts to answer long‑standing inquiries from the community and to document the city’s response to the disaster.