VOC sampling locations table for Ground Zero area, Jan 2002

NYC 9/11 Public Portal Document

A total of 12,676 ambient samples in lower Manhattan were measured by phase contrast light microscopy (PCM, used to identify structures greater than 5 pm in length), and 8,872 of these were also measured by transmission electronic microscopy (TEM; used to identify structures less than 0.5 pm in length). Only 23 samples were found to exceed the Asbestos Hazard Emergency Response Act (AHERA, which uses the TEM measurement technique) abatement standard of 70 structures per square millimeter (S/mm^), and there were no exceedences of the OSHA PEL (which uses the PCM measurement technique) of 0.1 fiber per cubic centimeter (f/cc). Most of the exceedences of the AHERA standard occurred during September 2001 adjacent to Ground Zero in “restricted zones”. The highest concentrations of PCM-measured fibers in ambient air were recorded during the 30 days following September 11,2001, at sites in the vicinity of the WTC. Concentrations during this time were in the range of 0.04 to 0.08 f/cc. There has been a steady decline in the asbestos levels through the first few months of 2002, to correspond to a steady background state of ND to <20 S/mm^ as measured by TEM and in the range of 0.003 J7cc as measured by PCM, a level which is typical for urban background.

A slightly higher occurrence rate of AHERA exceedences occurred within the exclusion zone at the Staten Island Landfill; 51 out of 5,207 samples taken. Most of the exceedences occurred during October and November 2001, corresponding to the time that most of the debris was being unloaded. Only one sample in Queens was above 70 S/mm\ whereas no exceedences were observed in the other boroughs of NYC or in New Jersey.

The highest measurements of asbestos available for evaluation in this report were taken within two apartments sampled on September 18,2001. One apartment was highly affected by die collapse of the WTC towers with completely shattered windows and dust piled throughout the apartment. The other was in a building that had little exterior damage, but had visible dust on surfaces within the building and in the apartment sampled. In the severely damaged apartment, five air measurements of asbestos ranged from 6277 to 10,620 S/mm^ using the AHERA protocol. One sample taken just outside on a window ledge of this apartment measured 548 S/mm^. However, it is likely this high reading was influenced by the air quality on the inside of the apartment, which showed exceedingly high asbestos concentrations, and was likely not representative of outdoor concentrations. The six indoor samples in the less impacted apartment exceeded the 70 S/mm^ AHERA standard at levels ranging from 141 to 379 S/mm7 A rooftop sample at this location was low at 6.5 S/mm^.

A systematic study of residential apartments by the NYCDOHMH and the ATSDR showed very little impact to residential apartments compared with this September 18 study, but still a difference between apartments in lower Manhattan and comparison apartments. From November 4 through December 11,2001, environmental samples were collected in and around 30 residential buildings in lower Manhattan. In addition, four buildings above 59th Street were sampled and used as a comparison area for this investigation. Importantly, asbestos was not detected above background levels in air samples in all apartments sampled (with background defined as 0.003 fi'cc, a level which is typical for urban background). Bulk dust samples were collected both indoors and on

DRAFT-DO NOT QUOTE OR CITE 9 October 2002

NYC-WTC_000149090