NYC-WTC_000232549

NYC 9/11 Public Portal Document

Mr. Steve Thompson October 24, 2001 Page 2

TWA = (Ti X Cl) 4- (T; X Cy) + (Ta x C.-,) + ... 480 Minutes Where:

Ti = 367 minutes 0, = 0.165 f/cc T2 = 30 Minutes C2 = 0.047 f/cc TWA = 0.129 f/cc

• The 8-hour Time Weighted Average for this sample set, calculated using both samples from this set, showed a value of 0.129f/cc.

• Sample # 101701JF11, which showed 0.165 f/cc when analyzed by PCM. yielded a concentration of less than 0.004 f/cc when analyzed by Transmission Electron Microscopy (TEM) utilizing NIOSH Method 7402. The laboratory analysis identified one asbestos fiber in this sample.

• One of the fourteen sample sets contained a short duration sample (# 101701PH02), which yielded a concentration of 0.123 f/cc when analyzed by PCM. Whole shift sampling could not be obtained (sample overloaded, as mentioned above).

• The Short-Term Exposure Limit (STEL) result of 0.123 f/cc is below the limit established by OSHA for the STEL and the other sample in the set that was representative of the remainder of the work shift was overloaded. The STEL was presumed to be representative of the whole shift exposure. Based on this presumption, the whole shift exposure would be presumed to be above the PEL. The calculation is done with the same formula for the TWA as presented above where Ci = 0.123 f/cc and Ti = is assumed to be 480 minutes.

• This same sample (#101701PH02), when analyzed by TEM using NIOSH Method 7402 identified no asbestos fibers.

• Pursuant to the request of DSNY, EE&G reviewed its notes regarding the DSNY “oiler" who wore the sample in which the asbestos PEL was exceeded. EE&G’s field industrial hygiene technician reported that the “oiler” was not wearing a respirator, when observed.

• The 0.129 f/cc result that was collected from the worker group “oiler” exceeded the OSHA defined PEL.

Metals and Silica/Total Particulate

On October 17 and 19, EE&G collected air samples for metals and silica/total particulate from DSNY workers performing the following job functions:

Dozer 003 operator, silica/total particulate. Truck counter, silica/total particulate.

CONFIDENTIAL, CITY_2IMCl00_008486379 SUBJECT TO PROTECTIVE ORDER NO. 2, SEPT. 2008

NYC-WTC_000232550