5 sampling efforts instead exposures were estimated

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5 sampling efforts; instead, exposures were estimated by having an adult use the sampling device at a lower height representative of a child’s breathing height. Introduction Asbestos air sampling was conducted at the CCMA on September 27 through 29, 2005. The asbestos air sampling and analysis approach and methodology are presented in the “Sampling and Analysis Plan for Asbestos Air Sampling, Clear Creek Management Area” (CH2M HILL, 2004). Breathing zone air samples were collected by adult study participants while performing recreational and occupational activities (i.e. activity-based samples), listed in Table 1. Using standard asbestos sampling techniques, air was sampled from the personal breathing space of the participants. This was done using a calibrated air pump attached to a plastic cassette, which contained an asbestos fiber-sampling filter. Concurrently, samples were collected at assumed child’s breathing zone levels, by the adult study participants, for similar recreational activities, as appropriate. The collected samples were sent to an analytical laboratory, EMSL Analytical, Inc., which analyzed the filters for asbestos type and concentrations in air by Transmission Electron Microscopy (TEM), using ISO 10312 methodology. The analytical results were compiled and reported as PCMe (Phase Contrast Microscope equivalent) fibers by Lockheed Martin REAC. The number of samples counted, and both minimum and maximum measured air concentrations of asbestos (exposure point concentrations) in units of PCMe fibers/cc (which are equivalent to fibers/ml), are presented for adult and child receptors (Table 2A and 2C). Minimum and maximum chronic exposure concentrations were derived from these measured air concentrations of asbestos as presented below. For this HHRA, exposures and risks were calculated using EPA based approaches and methodology as presented in the PTI Environmental Services HRA (1992), as described in the following sections. Quality Control Data Utilization: The laboratories that performed the asbestos counts reported a number of Quality Control (QC) sample types. Because of these differences in reporting, the sample results, and how they were utilized in the risk calculations, were treated differently depending upon their QC designation. On Table A1, non-detected values are reported as less than the sensitivity analysis value. The equation used to calculate the sensitivity analysis value is: Sensitivity (S) = Af / (k*Ag*V) Where: Af = the area, in square millimeters, of sampling collection filter; Ag = the area, in square millimeters, of TEM specimen grid opening; k = the number of grid openings examined; V = the volume of air sampled, in liters Listed below are the QC sample types, how they were used or considered in the risk calculations, and the rationale:
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6 Not QC sample , revised count: Use the latest revision, since multiple analysts determined the best definitions for fibers and the latest revision is their consensus opinion Recount same grid (RS) - Average the recounted sample results since they are
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