VOC sampling locations table for Ground Zero area, Jan 2002

NYC 9/11 Public Portal Document

elsewhere in the lower Manhattan neighborhoods surrounding the WTC, although more thorough analysis and modeling of potential PM exposures and correlation with health records is needed to evaluate this issue more fully.

It may be useful to place the above potential airborne PM exposures in perspective by comparing them to (a) exposures that occurred during some past notable PM air pollution episodes and (b) more recent historical data recorded for New York City areas. As discussed in U.S. EPA (1982,1986a) and Elsom (1992), a number of past severe air pollution episodes involved extended periods of exposure of urban populations to high concentrations of airborne PM and associated air pollutants such as SO2. In contrast to relatively brief periods (< 8 hours) of September 11 inhalation exposures on September 11,2001 to concentrations in the range of, and maybe in excess of, 1000-2000 pg/m’ of WTC-derived airborne coarse and fine PM, a number of past air pollution episodes in U.S. cities (e.g., Donora, PA in 1948; NYC in 1953 and 1962/63) and internationally (e.g., Neuse Valley, Belgium, 1930; London, UK in 1952, 1957, 1963) involved exposures to very high levels of PM that lasted for at least several days. Probably the most famous such episode occurred in London in December 1952, when millions of Londoners were exposed to daily PM levels (measured as British Smoke, which included high percentages of fine particles) of 1000-4000 pg/m’ (sometimes reaching hourly peaks of 6000 pg/m^ or more) on 3 to 5 consecutive days in the presence of 1000-4000 pg/m’ of SO2.

In NYC, PM2 5 values recorded on some days at the Ground Zero perimeter and occasionally elsewhere in lower Manhattan during late September and early October clearly exceeded the more usual background levels of fine PM seen in NYC since implementation of the PM NAAQS in the 1970s began to substantially reduce ambient PM concentrations in U.S. urban areas. For example, some ORD WTC perimeter site 24-hour PMj , measurements of more than 100 pg/m’ likely exceeded most - but not necessarily all - values recorded at the New York University Medical Center in an aerosol sampling study conducted in August 1976 (Lippman, et al. 1979), as per the mean value shown for PMj o samples in Table 2. However, the 24-hour PM2.5 concentrations (predominantly below 30-40 pg/m’) usually seen during most of the rest of October and into November at ORD WTC perimeter sites were notably lower than the 1976 values; and the PM2 5 levels reached by December and January generally compare favorably with PMj s values obtained at a monitoring site at the Bronx Botanical Gardens during February-June 2000. This Bronx site can be considered to be a relatively “clean” urban background site largely fi-ee of the effects of strong local sources. Maximum PM2 5 values ranged fi-om 35.4 to 43.3 pg/m’ fi-om three inter-compared collocated samplers at that Bronx site and average 24-hour PM2 5 values ranged fi-om 12.5 to 15.6 pg/m\ analogous to the mean PM2 5 concentrations shown in Table 2 for Boston and Philadelphia during February-June, 2000. Also, PM,o values for lower Manhattan sites, which were mainly in the range of 50-90 pg/m’ during October and mostly below 50 pg/m’ in November, were not markedly different from historical values observed in NYC. For example, the fourth highest and the maximum 24-hour PMk, values reported in the EPA Aerometric Information Retrieval System (AIRS) database for the five NYC boroughs during 1996 to 2001 ranged from 40-89 pg/m’ and from 51-121 pg/m’, respectively.

During September-October, 2001, concentrations of many elements, including heavy metals, at Ground Zero perimeter sites were at times much greater than those observed at several sites in the Northeast in February-June 2000. As part of a pilot study for EPA’s PM2 5 speciation

DRAFT-DO NOT QUOTE OR CITE 39 October 2002

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