WTC asbestos wipe sampling and cancer risk analysis, December 2001

NYC 9/11 Public Portal Document

A.

CONTRADICTORY ASBESTOS TESTING GUIDANCE

Impossible instructions from NYC PEP

The NYC Department of Environmental Protection (NYC DEP) gave impossible and unsafe instructions to owners of buildings. Furthermore, the instructions violated the standards set by the federal EPA. The NYC DEP advised building owners' to test dusts inside buildings to see if they were over 1%. They said that if the dusts were over 1%, a professional asbestos abatement contractor should be used for the cleanup:

EPA is using the 1% definition in evaLiating exterior dust samples in the Lower Manhattan area near the World Trade Center. All affected landlords have been instructed to test dust samples within their buildings utilizing this standard. Landlords were notified that they should not reopen any building until a competent professional had properly inspected their premise. If more than 1% asbestos was found and testing and cleaning was necessary, it had to be performed by certified personnel.

Unless the windows were blown out by the blast, interior dusts are in too thin a layer to enable them to be scooped up into a jar or bag. Only dusts that are in “bulk” form, which can be put into a bag or jar, can be tested for the percentage of asbestos.

If there is only a thin, visible surface dusting, or even an invisible layer of dust, you are forced to use what are called “wipe” samples or “microvacuum” samples. Wipe samples can only be tested for the number of asbestos fibers per area, not a percentage of asbestos in the total dust. Microvacuum samples are also typically only analyzed for number of structures per area, although there is a rarely used, very expensive ASTM method for microvacuum samples that can sometimes be employed to give mass concentration - percent values.

Laboratory results for settled dust layers are reported as “asbestos structures/square centimeter (structures/cm^).” This caimot be converted into a percentage of asbestos. Thus, it is almost impossible for building owners to even test for the 1% level in the first place. See the last section of this memca-andum for more information on asbestos sampling and analysis techniques.

NYC PEP instructions also contrary to stated EPA standard for the cleanup

The NYC DEP instructions also reversed the decision by the federal EPA that asbestos levels should be non-detectable. After the disaster, the federal EPA declared that it was applying the most stringent standard, namely the 70 asbestos structures per millimeter of air in the Asbestos Hazard Emergency Response Act (AHERA)? This “70" level is the lowest level that can be detected in air using the AHERA test method, because of the background level of asbestos in the filter through which the air is drawn. In other words, the level EPA stated that it required was NO detectable asbestos, not 1% or lower.

EPA regulations apply the 1% level to the asbestos containing materials themselves, such as insulation or asbestos floor tiles, not to the dusts that would result from the presence somewhere in the building of asbestos containing materials (ACM). EPA assumed that the dusts resulting from the presence of these ACM somewhere in the building would have much lower levels of

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