VOC sampling locations table for Ground Zero area, Jan 2002

NYC 9/11 Public Portal Document

Section V. Comment on the First Several Days After September 11

An event such as September 11 demonstrates that the greatest environmental impacts occur in the first 24 to 48 hours and in areas close to the site. Difficulties associated with site access and security, power supply sources, equipment availability and analytical capacity hindered efforts by EPA and the New York State Department of Environmental Conservation (NYSDEC) to put air monitors in place immediately after the attack. Region 2 collected numerous samples of dust on September 11 and the next few days, and analyzed them for asbestos and lead. However, the first air samples of some of the critical contaminants from Ground Zero and nearby were not taken until September 14, such as asbestos, while other contaminants were not sampled until September 23, such as dioxin. Rapid initiation of monitoring will allow the measurement of air concentrations that can be very important for evaluation of inhalation exposures and potential short and long-term human health impacts.

Therefore, very little data are available to quantify exposures which could have occurred in the hours and days following the collapse of the WTC towers on September 11. As discussed in all of the individual contaminant sections, the general trend was that air concentrations were elevated in the earliest samples, and that concentrations appeared to return to background within weeks to a few months. The section on particulate matter (PM) went further by speculating on what the air concentrations of PM might have been in the initial plume cloud that occurred on September 11, based on an empirical relationship between visibility and PM concentration. The PM section also included discussions on the findings published by Lioy et al. (2002), who sampled dust which had settled onto cars and other surfaces, and had been undisturbed when their sampling occurred a few days after September 11. The USGS has similarly sampled and reported on measurements of contaminants in dust and debris (http://speclab.cr.usgs.gov/wtc/). Modeling studies within EPA to evaluate the movement of plumes in the few days after September 11 are ongoing (preliminary results are presented in the PM section), and these may shed light on exposures which could have occurred during these few critical days. Epidemiological studies may also elucidate information on exposures during the first few days after September 11.

It seems apparent that higher concentrations would have been found in the time frame of about September 11 to September 18 compared to the concentrations that were found when monitors did get in place. The earliest ambient monitoring data within Ground Zero and in the closest monitors are the asbestos sampling results which were measured first on September 14. Benzene and PCB measurements were reported for September 16. Lead was reported starting on September 18, and PM2.5 was reported first on September 21. The first measurements for dioxin­ like compounds were not available until September 23.

Table 15 lists the first measurements on dioxin, asbestos, and lead in samplers within Ground Zero (the “WTC” sampler) and at locations bordering Ground Zero (e.g.. Church & Dey). The data on that table supports the hypothesis that higher concentrations were likely to have been present within the first few days after September 11 as compared to when monitoring did begin. As seen, generally the highest concentrations were the very first ones available or within the first week or two of sampling. It is also noted that for dioxin and lead, the monitoring stations on South End Avenue (Liberty & South End, Albany & South End, and Rector & South

DRAFT-DO NOT QUOTE OR CITE 122 October 2002

NYC-WTC_000148963