Q&A and FAQ regarding WTC response, Oct 2001

NYC 9/11 Public Portal Document MAY-29-2002 21:25 U.S. EPA/DEPP 212 6373772 P.06/08

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standard of 70. fZmml (.02 f.cc) is within EPA’s acceptable risk range of one-in ten thousand to one-in a million for carcinogens.

10. (There are no AHER.4 or other test methods for percent levels of asbestos in thin layers of settled dust)

Issue - Obtaining a percent level of asbe; .os is not possible when only a fine layer of settled dust is evident. Accordingly, instructions to landlords to determine if dust is greater than 1% asbestos may not be possible.

Response - This point is agreed upon; however, NYCDEP recommendations (9/26/01) advise building owners to use wet cleaning methods and HEPA filters where there is only a “light coating" (i.e, not enough to obtain percent level measurements) of dust. Also, as previously stated, EPA’s position has been that all WTC-related dust should be treated as potentially asbestos contaminated.

11. (Current EPA recommendations for Manhattan will leave most asbestos)

Issue - EPA recommendations for interior clean-up, specifically the use of dry HEPA vacuums, are ineffective and unsafe.

Response - The guidance that NYCDOH has provided for caipet cleaning (combination of diy HEPA vacuum and wet methods (i.e., shampoo) is consistent with the recommendations made in a study EPA performed on this subject matter. The report, Evaluation of Three Cleaning Methods for Removing Asbestos from Carpets: Determination of Airborne Asbestos Concentrations Associated vnth each Method (1993). recommends: “If ACM has been released onto a carpeted area during an operation and maintenance activity or as a result of fallen surfacing material, the gross debris should be removed by a HEPA-filtered dry vacuum cleaner, followed by wet cleaning of the caipet.” Additionally, the NYCDOH recommendations are consistent with the following EPA publications that provide guidance on asbestos removal from indoor envi’-onments. 1) AHERA (P. 659) states that cleaning of abated areas should be performed according to the following procedures: i) HEPA vacuum or steam clean all carpets. ii) HEPA vacuum or wet clean all other floors and all other horizontal surfaces. iii) Dispose of all debris, filters, mopheads and cloths in sealed, leak-tight containers. 2) Managing Asbestos in Place (OPPTS. 1990) recommends (P. 19) that the operation and maintenance of buildings with asbestos containing material should include routine cleaning of f oots using wet methods and/or the use of HEPA vacuums.

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