The air samples were analyzed using transmission electron microscopy (TEM) following the International Organization for Standardization (ISO) method 10312 (1995). As shown in the air sample analyses (Table 2), the asbestos concentration of all but one sample (i.e. Sample 5) was below the analytical sensitivity for the 8-hr time-weighted average (TWA)-permissible exposure limit (PEL) of 0.1 s/cc set by the Occupation Safety and Health Administration (OSHA). The asbestos concentration of sample 5 (i.e. 0.0048 s/cc) was measurable, but also below the OSHA TWA-PEL.

Table 2

Air sample asbestos results summary

Sample no.Number of asbestos structures detectedAnalytical sensitivity (s/cc)Asbestos concentration (s/cc)a
ND 0.0050 BAS
ND 0.0050 BAS
0.0048 0.0048
ND 0.0050 BAS
Field Blank-2 ND NA BAS
Field Blank-3 ND NA BAS
Sample no.Number of asbestos structures detectedAnalytical sensitivity (s/cc)Asbestos concentration (s/cc)a
ND 0.0050 BAS
ND 0.0050 BAS
0.0048 0.0048
ND 0.0050 BAS
Field Blank-2 ND NA BAS
Field Blank-3 ND NA BAS

s/cc, structures per cm3; ND, none detected; NA, not available; BAS, below analytical sensitivity.

aOSHA TWA-PEL = 0.1 s/cc.

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