A preliminary Environmental Protection Agency report finds that persons living or working near the Ground Zero site after Sept. 11 were unlikely to suffer adverse health effects. But those exposed to high levels of dust, asbestos, metals and other toxins during the collapse of the twin towers and for several hours afterward were at risk for immediate acute or chronic respiratory symptoms.
In the days following the Sept. 11th attacks, EPA and other federal and state public health and environmental authorities initiated numerous air monitoring activities to better understand the ongoing impact of emissions from that disaster. From the data collected, EPAs Office of Research and Development conducted a human health evaluation of exposure to air pollutants resulting from the WTC disaster.
In the draft evaluation, written in October but released Dec. 27, EPA researchers assessed the measured outdoor levels of various air pollutants, including particulate matter (PM), metals (lead, chromium and nickel compounds), polychlorinated biphenyls (PCBs), dioxin-like compounds, asbestos and volatile organic compounds (VOCs). The draft was published in the Federal Register Dec. 27 for a 50-day comment period. A panel of independent scientific experts will conduct a peer review of the findings.
Exposure to PM was generated by the collapse of the twin towers, the recovery and demolition operations and the lingering fire. Lead and asbestos were believed to be components of the WTC building materials. PCBs were used as dielectric fluid in transformers and capacitors. Dioxin and VOCs are produced as a result of combustion and volatilization from fuels. The assessment is limited to an evaluation mainly of the inhalation of airborne contaminants, although dust ingestion and dermal contact may also have led to exposures. Air samples were taken from monitors located at the perimeter of Ground Zero and at various other sites in lower Manhattan and surrounding areas.
The report notes that the first measurement of some of the contaminants was on Sept. 14, while others were not measured until Sept. 23. 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, according to the draft.
Ambient air levels found to be high, decreased to levels characteristic of pre-Sept. 11 levels by around January or February 2002.
Numerous other efforts have been conducted or are ongoing that address other aspects of exposure and potential risk associated with the collapse of the WTC.
An EPA official says the agency believes the rules don't violate the Clean Air statute. This official says, "Once these rules are in place and implemented...they will provide greater environmental benefits. We believe that at the end of the day, actions we have taken will be consistent with the Clean Air Act."