VOC sampling locations table for Ground Zero area, Jan 2002

NYC 9/11 Public Portal Document

approximately one to fourteen times the OSHA limit. These exposures occurred during: 1) pre-drilling /slurry wall 2) jack hammering, 3) rubble removal and loading operations near the Winter Garden; 4) during the breaking up of concrete in the pit; 5) while drilling the concrete slurry wall, 6) flagging operations in pit, and 7) 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/pit.

Similar to other results, very few exceedences of organic compounds were identified, including one exceedence for the benzene OSHA Allowable Limit of 1 ppm, and 8 PAH exceedences of OSHA's coal tar pitch volatile PEL of 0.2 mg/m^.

For metals, OSHA took a total of 1331 samples (excluding bulk and blank samples) to monitor worker exposures to dusts, fumes, oxides, and other compounds of metals such as antimony, beryllium, chromium, cobalt, copper, iron, lead, manganese, mercury, molybdenum, nickel, vanadium, zinc, cadmium, magnesium, and arsenic. Results from these samples were generally well below the applicable OSHA limits. However, torch cutting and burning structural steel at the rubble pile resulted in instances of overexposures as follows: copper (17); iron oxide (28); lead (19); zinc oxide (1), antimony (1); and cadmium (3).

There were 236 samples collected for employee noise, and 20 samples exceeded the OSHA PEL of 90 dBA.

VI.a.2. NIOSH Data The NIOSH sampling occurred between September 18 and October 14,2001. The focus was on search-and-rescue persoimel, heavy equipment operators, and workers cutting metal beams, but other occupations were also sampled. A total of 1174 air samples were taken, including 804 for asbestos. The New York City Department of Health and Mental Hygiene (NCDOHMH) collected most of the asbestos samples, while NIOSH personnel collected all other samples. In addition to air samples, 33 samples of dust, debris, and other materials were taken. NIOSH has reported on results for asbestos, metals, respirable particulate, CO, hydrogen sulfide, inorganic acids, VOCs, elemental carbon, Freon™-22, and PAH (CDC, 2002).

The bulk samples mostly showed asbestos concentrations at <1% (by mass); 3 of 29 samples had mass concentrations ranging from 1-3%. Analysis of air samples for asbestos by PCM revealed fibers in 358 of 804 samples (45%). Of 25 samples measured by PCM which exceeded the 0.1 free REL, 18 were measured then by TEM, and all had asbestos concentrations less than 0.1 free. Differential analysis by polarized light microscopy of these 25 air samples revealed that most nonasbestos fibers were fibrous glass, gypsum, and cellulose.

Air concentrations of total (36 samples) and respirable (18 samples) particles showed maximum concentrations of 2.3 and 0.3 mg/m’, respectively, which are below the corresponding RELs of 10 and 5 mg/m’ for Portland cement. Respirable crystalline silica was not detected in any of the 18 samples measured for it.

Two instantaneous peak CO measurements exceeded the 1,200 ppm level (at 1239 and 1369 ppm), the level NIOSH considers an immediate danger to life and health. One was from a

DRAFT-DO NOT QUOTE OR CITE 126 October 2002

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