NIOSH Air Sample Summary Report for WTC Response Sept-Oct 2001

NYC 9/11 Public Portal Document

majority of the fibers reported from the PCM analyses are non-asbestos fibers. Further analyses are being performed to determine the nature of these non-asbestos fibers.

Carbon Monoxide: A total of 98 air samples were collected for carbon monoxide indicating TWA concentrations ranging from 0.16 to 242 ppm. All but 4 of these measurements were below the NIOSH REL of 35 ppm and all but 1 were below the OSHA PEL of 50 ppm. One sample (242 ppm) exceeded the NIOSH recommended ceiling limit of200 ppm. Additionally, 2 instantaneous peak measurements (1,239 and 1,368 ppm) exceeded the NIOSH unmediately dangerous to life or health (IDLH) value of 1,200 ppm and 15 others exceeded the NIOSH recommended ceiling limit of200 ppm. All carbon monoxide measurements exceeding one or more of these evaluation criteria were being performed by workers using either a cutting torch or a cutting saw. This underscores the need for adequate ventilation and worker awareness when using these tools.

Diesel Exhaust: A total of 8 air samples were collected for diesel exhaust indicating TWA (elemental carbon) concentrations from none detected to 0.023 mg/m^. These measurements are all well below the proposed American Conference of Governmental Industrial Hygienists (ACGIH®) threshold limit value (TLV®) for diesel exhaust of 0.20 mg/m^ (element^ carbon). (NIOSH and OSHA currently have no evaluation criteria for diesel exhaust.)

Freon® 22: A total of 5 air samples were collected for Freon® 22 (chlorodifluoromethane). No Freon® 22 was detected on any of these air samples.

Hydrogen Sulfide: A total of 10 air samples were collected for hydrogen sulfide. Hydrogen sulfide was detected on only 1 of these samples indicating a TWA concentration of 1.0 ppm and a instantaneous peak concentration of 3.0 ppm. These measurements are well below the NIOSH recommended ceiling limit and the OSHA ceiling limit of 10 ppm.

Inorganic Acids: A total of 27 air samples were collected for inorganic acids including hydrobromic, hydrochloric, hydrofluoric, nitric, phosphoric, and sulfuric acids. Except for sulfuric acid, only trace amounts of inorganic acids were detected on these samples. Small quantities of sulfuric acid were detected on all but 1 of the air samples which were below the NIOSH REL and OSHA PEL of l.Omg/m^

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