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VOCS IN AMBIENT AIR NEAR WORLD TRADE CENTER SITE
Citation:
Seila, R L. AND W A. Lonneman. VOCS IN AMBIENT AIR NEAR WORLD TRADE CENTER SITE. Presented at 12th Conference of the International Society of Exposure Analysis, Vancouver, Canada, August 11-15, 2002.
Impact/Purpose:
The overall goal of human exposure research in air toxics is to develop the methods, data, and models of exposure that will provide the scientific basis for EPA to move to a risk-based program and that will enhance NATA. Specific objectives for this measurement task are to:
o Characterize exposure concentrations and variability in critical microenvironments using targeted measurement studies;
o Quantify the relationship of personal exposure to ambient and indoor concentrations;
o Identify critical microenvironments, human activities, and factors influencing exposure to air toxics;
o Develop methods to quantify exposure from background, point or area sources, and microenvironmental sources;
o Evaluate aggregate and cumulative exposures.
Description:
Beginning on September 22, 2001 and continuing through February 2002, ambient air samples were collected at three sites within a block of ground zero and at a fourth site on the 16th floor of a building at 290 Broadway. Grab samples were collected in evacuated, electro-polished stainless steel canisters. The canisters were returned to Research Triangle Park for determination of C2 to C10+ volatile organic compounds by capillary GC-FID with cryogenic preconcentration. The limit of quantitation is less than 1 part-per-billion (ppb). Some samples were analyzed by GC-MSD. Of 193 samples collected 96 have been analyzed and qualified.
In general concentrations were highest at the site north of ground zero followed by the southerly site and 290 Broadway. Some compounds showed a trend with maximum concentrations at the beginning of the study period followed by a decrease to background levels around mid-November. This behavior was displayed by the following compounds in order of decreasing abundance with maximum concentration indicated: ethylbenzene (44 ppb), benzene (26 ppb), propylene (21), toluene (16 ppb), xylenes (6 ppb), styrene (5 ppb), and naphthalene 1 ppb). All of these compounds are also present in vehicular emissions and gasoline. After November, when levels had returned to background, there was no significant concentration difference between the sites.
Other compounds that are prominent in automobile exhaust and gasoline showed very little or no discernable trend. In this category, with maximum concentration indicated, were acetylene (59 ppb), n-pentane (28 ppb), isopentane (34 ppb), ethylene (32 ppb), benzaldehyde (7 ppb), and decane (3 ppb). Other abundant light hydrocarbons without a trend were ethane (59 ppb), propane (26 ppb), n-butane (24 ppb), and isobutane (18 ppb).
This is an abstract of a proposed presentation and does not necessarily reflect the United States Environmental Protection Agency (EPA) policy. The actual presentation has not been peer reviewed by EPA. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.