Memo on asbestos dust sampling methods, May 2002

NYC 9/11 Public Portal Document

In 1999, the ASTM issued a standard test method for wipe sampling of surfaces. The limitations of this test method were similar to the limitations indicated for the microvacuum technique. This method also has not been adopted by any State or local regulatory agency.

A single direct relationship between asbestos-containing dust and potential human exposure has not been established. Although, a direct relationship between dust levels and exposure has been dociunented for other contaminants, including lead, this relationship has not been documented for asbestos fibers probably due to the unique aerodynamic aspects of asbestos fibers.

The scientific community is split on the use of a k-factor for evaluating the relationship between asbestos-containing dust and potential human exposure. The k-factor is expressed as the amount of asbestos in a volume of air divided by the amount of asbestos in the surface dust. The k-factor is a function of surface type, physical activity and the composition of the dust. The application of the k-factor to the response actions for the WTC is therefore questionable.

The circulation of air in conjunction with air sampling provides direct information on potential exposure. Asbestos is primarily an inhalation hazard that has been associated with lung cancer, mesothelioma, and asbestosis. The information is well established and is the basis for clearance air sampling in regulatory standards.

Clearance air monitoring following an asbestos removal project requires the use of forced air equipment to reentrain settled asbestos fiber and the collection of air samples during air circulation procedures. This methodology provides a direct evaluation of cleaning activities and has promulgated clearance criteria.

Individuals are trained and certified for collection of air and bulk samples. The training and certification requirements include units on hazard assessment, selection of sampling locations, and proper sample collection of air and bulk materials. Individuals are not uniformly trained or certified for collection of asbestos dust samples.

Further, conversations with the New York State Department of Health indicate that asbestos dust sampling and analysis procedures have not been adopted due to the lack of precision. Laboratories participating in the Environmental Laboratory Approval Program are not accredited to perform dust sample analysis. Reported results of dust sample analysis must indicate the laboratory is not accredited for the performance of the analysis.

NYC-WTC_000153166