NYC-WTC_000234890

NYC 9/11 Public Portal Document

Mr. Steve Thompson October 24, 2001 Page 3

• Barge operation, metals. • Pay Hauler, metals. Samples were sent to EMSL for analysis by inductively coupled plasma (ICP) following NIOSH method 7300. The laboratory analyzed for 8 metals including; arsenic, barium, beryllium, cadmium, total chromium, lead, selenium, and silver. Results were reported as micrograms of each metal per cubic meter of air (ug/m®). The method selected did not differentiate between soluble and insoluble forms of chromium. As such, the reported concentrations did not identify hexavalent chromium from other forms of the metal.

Silica/total particulate samples were collected by drawing a known volume of air across a 37 millimeter poly- vinyl chloride pre-weighted filter. These samples were also sent to EMSL for analysis. Samples were first weighed to determine total particles, and were then analyzed by X-ray diffraction microscopy following NIOSH method 7500. Results were reported as milligrams per cubic meter of air (mg/m’) for both parameters.

The metal samples did not identify concentrations of metals at, or above the current OSHA PEL for the individual constituents. The current exposure limits for each of the metals is presented below:

Arsenic 10 ug/m’ Barium 500 ug/m',3 Beryllium 2 ug/m’ Cadmium 5 ug/m’ Chromium 50 ug/m’ Lead 50 ug/m’ Selenium 200 ug/m,3’ Silver 10 ug/m’

The silica/total particulate samples did not show concentrations at or above the current OSHA PEL of 0.1 mg/m® for silica and 10 mg/m^ for total particulate.

A copy of the laboratory results and chain of custody forms for metal and silica/total particulate analysis are attached to this letter.

RECOMMENDATIONS

• The PCM method was developed by NIOSH to provide a rapid and inexpensive method to evaluate exposure to airborne asbestos fibers. While the method is not specific to asbestos fibers, and will count any fiber that has a certain morphology, the method is approved by OSHA as the preferred method of analysis for worker exposure to airborne asbestos. EE&G recognizes the potential limitation of the PCM method as applied to the current project, and has implemented the analysis of samples found to exceed the PEL by TEM. The TEM method will verify the presence or confirm the absence of asbestos fibers within a defined size range through a method utilizing discriminatory analysis. This method is limited to counting only those fibers greater than 5 microns in length and 0.5 microns in diameter (the same rules governing size as the NIOSH Method 7400). One should not presume that

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