Q&A and FAQ regarding WTC response, Oct 2001

NYC 9/11 Public Portal Document MAY-29-2002 21:23 U.S. EPA/DEPP 212 6373772 P.04/0B

5. (Asbestos does not leave buildings with ordinary cleaning methods)

Issue - The asbestos contamination if not going to leave buildings in Manhattan by itself with ordinary cleaning any more than it will in Libby.

Response - It has been the longstanding position of EPA that all WTC related dust should be treated as potentially asbestos contaminated and should be cleaned in a professional manner by HEPA and/o? wet methods. Where significant amounts of dust and/or debris exist, hTfCDEP has provided guidance to property owners bn building clean-up. Where there is minimal dust, NYCDOH has recommended the use of wet cleaning methods and HEPA vacuuming. In conjunction with the NYCDOH, ATSDR is conducting indoor air sampling for asbestos in WTC area residences to, among other things, evaluate the effectiveness of cleaning methods. EPA has supported this study.

6. (EPA’s crude air testing .annot deU^A hazardous levels of asbestos)

Issue - EPA is using the Asbestos Hazard Emergency Response Act (AHERA) transmission electron microscopy (TEM) clearance test and claiming that if it shows 70 or fewer asbestos structures per mm2, then the air is safe.

Response - EPA has utilized the AHERA re-occupancy standards for schools to evaluate the ambient air in Lower Manhattan and elsewhere in New York City to provide information pertinent to long-term public health concerns, and best management practices for the debris removal operations. The AHERA standard of 70 lZmm2 is based on the background contamination of blank asbestos sampling filters. EPA has evaluated the AHERA standard in a risk context, and it meets EPA’s criteria for protectiveness (less than a one-in ten thousand excess lifetime cancer risk) for a continuous one year exposure duration. This was estimated to be the reasonable maximum exposure duration for WTC-rclated contaminants. Also, the AHERA standard has been employed in Libby to determine residential occupancy with the understanding that additional analysis would be performed to evaluate long-term exposure.

7. (EPA’s crude air testing cannot detect hazardous levels of asbestos)

Issue - Memo states that 70 f/mm2 (.02 fee) is the lowest level that the method (AHERA) can delect.

Response - EPA, in utilizing the AHERA standard, has employed an analytical tool (TEM) that is widely acknowledged to represent the state of the science in airborne asbestos analysis. The AHERA standard of 70 f7mm,7 ’«the school re-entry criteria, not the detection limit. The standard is based on the bav&ground contamination of blank sample filters. In effect, the AHERA standard was intended to insure drat the remediation of asbestos conataining material (ACM) in schools would be deemed complete when results of air sampling in the impacted area were statististically indistinguishable .from background contamination of blank filters. The actual detection limits of TEM are a function of grid openings (i.c., filter area) analyzed and the sampling air volume. As prescribed by AHERA, the method sensitivity is .005 fZee, not .02 fee.

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