E-mails R. Avaltroni 2002

NYC 9/11 Public Portal Document

Dr. Mark A. Maddaloni Senior Toxicologist U.S. EPA, Region II 290 Broadway New York, NY 1 EH7

Mr. Matthew Onek Special Advisor to the Chancellor New York City Department of Education 52 Chambers Street New York, NY 1 OS7

Dear Mr. Onek:

EPA has reviewed the sampling results conducted by Taylor Environmental for the NYC Dept. of Education re: asbestos air sampling at select locations in Stuyvesant HS during August, 2002. The air sampling results at all locations (auditorium, library and principal’s office) meet the clearance criteria (70 s/mm^) set forth in the Asbestos Hazard Emergency Response Act (AHERA) for re-entry into schools.

The EPA method (EPA-600/J-93/167) to test carpet for asbestos by ultrasonification is intended to determine the total asbestos content imbedded in a carpet and to evaluate the efficiency of carpet cleaning methods. There exists no widely recognized correlation between asbestos concentration (fibers per unit area) in carpet as measured by ultrasonification and associated air concentrations. Accordingly, it is not feasible to assess the risk posed from asbestos as measured by this method.

Positive ultrasonification results indicate a potential, albeit of unknown magnitude, for asbestos exposure. Actual risk from asbestos is best determined by air sampling.

Another method that can be employed for measuring asbestos on porous surfaces is the “microvac” technique developed by the American Society for Testing and Materials (ASTM Method D5755-95). Investigators (* Millette and Hays, 1994) have evaluated the relationship between asbestos load (frcm^) on surfaces and corresponding concentrations (free) in the indoor air during various types of activities. However, these relationships (referred to as “K” factors by the authors) have been developed primarily from studies on hard surfaces. In addition to activity, a K factor (i.e., relationship between asbestos surface and air level) will be influenced by room volume and air exchange rates as well. Due to a lack of adequate empirical data, an estimation of airbome asbestos concentration based on extrapolation of asbestos load (frem^) data from a “microvaced” porous surface would be highly uncertain.

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