VOC sampling locations table for Ground Zero area, Jan 2002

NYC 9/11 Public Portal Document

indicate that large percentages of firemen caught in the initial WTC dust cloud and others who worked at Ground Zero during the first 2 to 7 days post September 11 experienced respiratory (e.g., “WTC cough” and/or bronchial hyperactivity) or other symptoms that still continue to persist for some individuals several months after cessation of exposures at WTC Ground Zero.

During the week following September 11, the plume from initial high-intensity WTC fires appears to have been largely convected upwards and dispersed mainly to the south-southeast or south-southwest without much evident ground level contact, except perhaps for a few hours on the mornings of September 12 and 13, when it flowed to the east-southeast of the WTC. This resulted in briefly increased hourly PM2 5 levels at sites in lower Manhattan (166 pg/m^ at PS 64 on 9/13) and in Queens (100 pg/m^ at PS 199 on 9/13). Probably few people were exposed around the PS 64 site, given the restrictions in effect on motor vehicular or pedestrian traffic below 14* Street imtil September 14, but some may have been briefly exposed in the vicinity of the PS 199 site and/or at locations between the two sites. Although it is doubtful that the brief, several-hour PM2 5 excursion on the morning of September 13 resulted in harmful PM exposures, retrospective examination of physician and emergency department visits and/or hospital records in the affected areas may help to verify this.

After September 21, EPA/ORD monitoring indicated initially high levels of WTC-derived airborne particles (especially at certain Ground Zero perimeter sites) during late September and early October, but occurrences of PM excursions decreased over time through late October and into November. The rate of decrease in concentrations was not uniform throughout the monitoring period; rather, there were episodes of high PM levels spaced between periods of much lower concentrations. The frequency of the episodes was highest during the first month following the collapse of the WTC buildings and then declined afterwards. For example, notable PM emission episodes occurred during the first month of sampling, as shown in Figure 11. PMjs concentrations varied over a wide range (sometimes exceeding the relevant AQI40 pg/m’ action level) during late September and early October at EPA/ORD WTC perimeter Site A. The concentrations of a number of elements measured at this site also showed large day-to-day variability, as shown in Figures 14-18. On a number of days in late September and early October, concentrations of several elements were many times higher than the more typical background levels recorded for December-January, after the WTC fires had largely or entirely burned out.

On the basis of overall air quality results summarized above, it appears that 24-hour PM,,, and PM2 5 values throughout most all of the NYC metropolitan area generally remained at or returned rather quickly to historical background levels and WTC PM emissions posed no increased health risks beyond those due to usual PM levels for most areas of NYC. On the other hand, high PM2 5 concentrations recorded on the perimeter of Ground Zero during late September and early October may imply increased health risks for the most highly exposed individuals (that is, persons who spent extended periods of time within the WTC Groimd Zero work zone without wearing protective respirators). Specifically, acute exposures to irritating materials present in either the PM2 5 or coarse particle components of PM,o, especially during any high hourly peak excursions, may have contributed to acute or continuing respiratory symptoms reported by some workers and/or residents in lower Manhattan areas in the immediate WTC vicinity. It is much less likely that any markedly increased health risks were posed by ambient air PM exposures

DRAFT-DO NOT QUOTE OR CITE 38 October 2002

NYC-WTC_000149119