Law Department notice on WTC document preservation, Oct 2001

NYC 9/11 Public Portal Document

EPA did not have health-based benchmarks for airborne asbestos nor for asbestos in bulk dust. Consequently, EPA used criteria from two programs originally developed for other purposes.

Asbestos Ha&ird Emergency Response Act (AHERA): Criteria for this program were developed for air monitoring inside schools following an asbestos abatement program, to clear those schools for re-entry. For the WTC testing, EPA used AHERA criteria to evaluate the ambient (outdoor) air quality for asbestos. However, this is not a health-based standard. The AHERA standard for re-entering schools was established at 70 structures per millimeter squared (s/mm2) in 1987 because this was considered to be the amount of background contamination found on the filters used to collect air samples when the AHERA standard was issued. Due to filter improvements over the years, the amount of background contamination today is considerably less, but the AHERA standard has not been revised.

Asbestos National Emissions Standards for Hazardous Air Pollutants (NESHAP): Criteria for this program were developed to identify asbestos-containing material subject to demolition and renovation work practices. This criteria states that material containing at least 1 percent asbestos, by volume, is considered asbestos-containing material and subject to EPA’s NESHAP regulations. The 1 percent threshold, based on the smallest amount that can be measured using Polarized Light Microscopy, is not a health-based standard. This was emphasized in a September 19 e-mail from an EPA Branch Chief, who has testified as an Agency expert at an asbestos penalty hearing that: “Additionally, 1% asbestos in a material is not a safe level of asbestos [emphasis in original quotation]... one-half percent asbestos-containing material (ACM) could be just as hazardous as 20% ACM depending on the condition of the material and how it is handled.” New York City also recommended that building owners use this I percent benchmark in determining whether the interior of buildings should be cleaned for asbestos (see Chapter 3).

Guidelines were not available to assess the impact of acute (up to 8 hours) exposures. People caught in the initial debris and dust cloud on September 11 were potentially exposed to high levels of various pollutants for a short duration. EPA has been funding a program to develop Acute Exposure Guideline Levels (AEGLs), but none of these levels had been finalized at the time of the WTC disaster. The program had developed several draft AEGL’s but these draft AEGLs were not applicable to the pollutants of concern at the WTC site.

In general, EPA did not have benchmarks to evaluate short-term exposures such as those experienced from the WTC collapse. For the WTC situation, EPA adjusted the Superfund 30-year exposure benchmarks to 1-year (short-term) exposure benchmarks. (See Appendix D for a list of benchmarks used by EPA in

12 Report No. 2003-P-00012

NYC-VVTC_000145367