NYC-WTC_000231627

NYC 9/11 Public Portal Document

while drilling the concrete slurry wall, and 6) 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 occuired were in the rubble pile/pit; an area where OSHA continues to encourage the use of respiratory protection.

Organic Compounds: OSHA has taken 579 samples (excluding bulk and blank samples) for (VOCs) such as acetaldehyde, acrolein, acrylonitrile, benzene, 2-butanone, carbofurans, PCBs, ethyl benzene, formaldehyde. Freon R-22 (chlorodiflouromethane), hexone, isocyanates (e.g. MDl, TDl), perchloroethylene, phosgene, styrene, 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 a benzene sample taken was found to be at the 8-hr. OSHA Allowable Limit concentration of 1 ppm. This was found on a backhoe operator moving debris on 10/7/01. See information below for polynuclear aromatics. Freon R-22, phosgene and dioxin.

Inorganic Acids OSHA has taken approximately 75 samples for inorganic acids such as hydrochloric, phosphoric, and sulfuric acids. Two samples for sulfuric acid were found to exceed OSHA’s permissible exposure limit (PEL) of 1 mg/m^.

Oxides of Nitrogen/ Sulfur: Sampling on grappler operators on the rubble pile, and on employees at the truck wash stations revealed trace levels of nitric oxide and nitrogen dioxide. This was repeated (1) sample, now that the wash station is been enclosed. SO2 personal and area results were found to be below OSHA limits.

Metals: OSHA has taken 784 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, molybdenum, nickel, vanadium, zinc, cadmium, magnesium, and arsenic. Results from these samples are generally well below the applicable OSHA limits. However, torch cutting and burning structural steel at the rubble pile have resulted in instances of overexposures as follows: copper (12); iron oxide (23); lead (12); and cadmium (2). Accordingly, OSHA is recommending that workers engaged in these operations wear appropriate respiratory protection.

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CITY_21MC100_010177962

NYC-WTC_000231628