NYC-WTC_000205208

NYC 9/11 Public Portal Document

■Latest WTC Air Monitoring Summaries Page 1 of 3

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Protecting the Safety and Health of America's Wort

OSHA SAMPLING RESULTS SUMMARY AS OF 11/8

Asbestos A total of 642 air monitoring samples for asbestos have been taken. From J 9/13 - 9/21, 177 samples were taken in the financial district. They were taken on OSHA personnel as they walked within certain predetermined zones. Results revealed asbestos concentrations ranging from none detected, (ND), to 0.037 f/cc., Weil below OSHA's permissible exposure limit (PEL) of 0.1 f/cc.

After 9/21, sampling focused on the rubble pile and those workers working on or immediately next to it. 63 of 465 samples exceeded OSHA's limit via PCM analysis. However, upon further analysis using discriminating counting methods and/or TEM analysis, the number of asbestos fibers found dropped dramatically to below detectable levels or well below 0.1 f/cc.

Carbon Monoxide A total of 47 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.

Noise OSHA has been conducting noise monitoring in the rubble pile. Twelve personal samples have been conducted on employees performing, (or working near), various operations, such as jack hammering. Employee exposure to the noise range from 80.6 dBA to 89 dBA. OSHA's permissible noise exposure for construction is 90 dBA.

Respirable Silica The overwhelming majority of the 226 silica samples show no detectable levels of airborne silica. The highest sample result was approximately twice the OSHA limit, whereas the next highest level was less than half of this limit. Both of 3 these levels were found on personnel working in the rubble pile, an area where OSHA continues to encourage the use of respiratory protection.

Volatile Organic Compounds OSHA has taken 366 samples for volatile organic compounds, (VOCs), such as acetaldehyde, acrolein, acrylonitrile, benzene, 2-butanone, carbofurans, chlorodiphenyl (PCB), ethyl benzene, formaldehyde. Freon R-22 (chlorodiflouromethane), hexone, isocyanates (e.g. MDI, TDI),

http://www.osha.gov/nyc-disaster/suinmary.htnil 11/10/2001

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NYC-WTC_000205208