OSHA sampling results summary, World Trade Center, Dec 2001

NYC 9/11 Public Portal Document

OSHA SAMPLING RESULTS SUMMARY AS OF 12/22 A.sbesuis- .A ictal of 910 air monitoring samples for asbestos have bee 1 ■ten. From 9-1; -A21. 1'7 samples were taken in the linanciai disiric;. They we ken ;n OSHA .’ers.mne! .n they walked within certain predetermined zone i. Results revealed asbestos concentrations ranging from ND (.none detected) to 037 f ee., well below OSHA's permissible e.xposure limit (PEL) of.! fee. .After 9 21. sampling focusedcn the rubble pile and those workers working on or immediately next to it. 82 of the samples analyzed exceeded OSHA's limit via PCM analysis. However, upon fupher analysis using discriminating counting methods and/or TEM analysis, the number of asbestos fibers found dropped dramatically to below detectable levels or well below .1 fee.

Carbon Monoxide: A total ot 77 personal samples of workers on the rubble pile showed results ranging from 1 ppm to 34 ppm which are well below the OSHA 50 ppm permissible exposure limit.

Auisc; OSHA has been conducting noise mcnitoring in the nibble pile. 41 personal samples have been conducted on employees performing (or working near) various operations such as jack hammering, drilling and equipment operations. Employee’s e.xposure to the noise range from 73.7 dBA to 94.5 dBA. OSH.A’s permissible noiseexposure for construction is 90 dB.A. One personal sample and one area sample during core drilling operations exceeded the OSH.A noise PEL of 90 dBA. OSHA continues to recommend the use of appropriate hearing protection for workers performing tasks where high noise levels are likely to be encountered. Respirable Silica: The overwhelmi.ng majority of the 408 silica samples show no detectable levels of airborne silica. However, fourteen e.xposures exceeded the PEL. The highest sample result was approximately nine limes the OSH.A limit (pre-drillers working on the slurry/ or "bathtub" wall). The oilier twelve elevated exposures were approximately one to seven times the OSH.A limit. These exposures occurred during; I)rubble removal and loading operations near the Winter Garden; 2) during the breaking up of concrete in the pit; 3j while core drilling the concrete slurry wall, and 4) while chipping concrete with power tools during demolition activities at 7 WTC's parking garage. Most of the work areas where apparent overexposures to silica occurred were in the rubble pile; an area where OSHA continues to encourage the use of respiratory protection. \’olatile Organic Compounds: OSH.A has taken 608 samples for (VOCs) such as acetaldehyde, acrolein, acrylcnitTiie, benzene, 2-butanone. carbofurans, chlorodiphenyl (PCB). ethyl benzene, formaldehyde, Freon R-22 (chloroditlouromeihane). hexone, isocyanates (e.s, MIDI, TDI), perchloroethylene, phosgene, sixTene, toluene, 1-3 butadiene, trichloroethylene, vinyl chloride, glutaraldehyde, and xylene. Screening samples initially showed elevated levels of some organic chemicals resulting from the fires burning in the rubble pile. Subsequent personal and area samples show worker exposure levels to be below OSHA limits. However, one personal sample result for benzene was found to be at the S-hr. OSH.A Allowable Limit concentration of I ppm. This was found or a baclthoe operator moving debris. See information below for polynuclear aromatics. Freon R-22, phosgene and dioxin.

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