US EPA

Following the collapse of the World Trade Center towers on September 11, 2001, New York State and Federal agencies initiated numerous air monitoring activities to better understand the ongoing impact of emissions from the disaster. This report focuses on these air measurement data, evaluating them in terms of what is typical for New York City or general urban background and interpreting it with regard to the potential for human health consequences. The report does not evaluate exposures possibly faced by rescue or clean-up workers and briefly discusses past and current indoor monitoring efforts.

The analysis in this report supports three general findings: 1) Persons exposed to the extremely high levels of ambient particulate matter and its components during the collapse of the World Trade Center towers and for several hours afterwards were likely to be at risk for immediate acute (and possibly chronic) respiratory and other types (e.g., cardiovascular) of symptoms. 2) The first measurements of some of the contaminants were on September 14, while other contaminants were not measured until September 23. Available data suggest that the concentrations within and near Ground Zero were likely to be highest in the few days following September 11. Because there are only limited data on these critical few days, exposures and potential health impacts cannot be evaluated with certainty for this time period. 3) Except for exposures on September 11 and possibly during the next few days, persons in the surrounding community were unlikely to suffer short-term or long-term adverse health effects caused by exposure to elevations in ambient air concentrations of the contaminants evaluated in this report. These elevated concentrations were measured mostly within and near Ground Zero, and they lasted for one to three months after September 11.

The monitoring data indicate that air concentrations decreased to background levels that are characteristic of pre-September 11 levels in the New York City metropolitan area by around January or February of 2002.

This report was released for public review and comment in December of 2002. In July of 2003, an expert panel met in New York City to review this document. A report on their deliberations has now been completed and is posted below. This report captures the main points and highlights of the meeting, including a compilation of the individual reviewers' comments, summaries of the panel discussions, and appendices which include comments and materials provided by the public during the meeting. EPA is in the process of addressing the expert comments heard at the meeting, as well as the public comments.

U.S. EPA. Exposure and Human Health Evaluation of Airborne Pollution from the World Trade Center Disaster (External Review Draft). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-02/002A, 2002.