DEP memo on vehicle release from Ground Zero, January 24,

NYC 9/11 Public Portal Document 1-24-02 ; 12:30PM;NYC Law Department ;i2i236i8Y65 # 15/ 55 JFlN-22-2002 09=50 O5EP UNIT RM. 7345 202 324 9235 P. 11/43 Industrial Hygiene Survey_________________________ Federal Bureau of Investigation, Staten Island, NY

Cobalt O.l mg/M3 Chromium I mg/M3 Copper I mg/M3 Iron 10ms/M3 Lead 0.05 mg/M3 Magnesium 15 mg/Mj Manganese 5 mg/M3 Nickel lmg/M3 Thallium O.l mg/M3 Vanadium 0.5 mg/M3 Zinc 5 mg/M3

Silica Dust Crystalline silica is found in materials such as concrete, masonry and rock. When these materials are made into a fine dust and suspended in the air, such as in the WTC buildings, breathing in these fine particles can produce lung damage, leading to a disease called silicosis. The crystalline silica dust limit is for respirable dust (<10 microns) and is regulated as an eight-hour time weighted average. The current OSHA PEL for respirable dust containing crystalline silica (quartz) for the general industry is measured by (mg/M3) and is calculated using the following formula; PEL - 10mg/M3 % silica +2

In addition, for cristobalite and tridymite forms, the same formula should be used for determining the PELs, divided by one-half. The National Institute for Occupational Safety and Health's (NIOSH) recommended exposure limit (REL) for respirable crystalline silica is 0.05 mg/M3 (50 mg/M3) for up to ten hours/day during a 40-hour work week. Where no silica detected in the sample the PEL is 5 mg/m3. Where the sample is 100 % quartz the PEL is 0.1 mg/m3. This gives a range for permissible exposure limits for respirable dust of 0.1 to 5 mg/m3 depending upon the crystalline silica content.

Volatile Organic Compounds The charcoal tube samples were desorbed and scanned on a gas chromatograph for 36 different volatile organic compounds. The detection limit for each VOC ranged from 3 to 5 micrograms. The volume of air sampled for the VOC samples ranged from 60 to 80 liters. This gives a detection limit for each VOC ranged from 0.04 to 0.06 mg/m3. The compounds tested have permissible exposure limits that range from the lowest limit for benzene of 3 mg/M3 to the highest limit set for acetone of 2400 mg/m3. The OSHA Z tables provide the permissible exposure limit for each of the compounds tested. In the results section of this report the PEL is provided for each of the compounds detected.

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