NIOSH 7501 (Issue 3)


This method is specific for amorphous silica in crystalline (e.g., quartz) matrices in the range 1 to 10 mg/m3 for a 200-L air sample. Amorphous silica usually contains some crystalline silica. See also discussion of crystalline silica in Chapter R of this volume. Silica is common found in nature as a mineral quartz.

Analysis Type (Application Method): X-ray powder diffraction

Link to NIOSH 7501 (Issue 3) Method

Compatible Filters:

C Total dust: 37mm filter holders type 5.0 μm PVC supported with backup pad in a two piece, 37 mm cassette filter holder (preferably, conductive) held together by tape or cellulose shrink band. Respirable dust: PVC (as above) plus cyclone, 10-mm nylon or Higgins-Dewell (HD), with sampling head holder. Additional filter 25 mm 0.45 μm PVC with 25mm filtration apparatus, alignment guide, side-arm vacuum flasks and 25 and forceps to handle filter membrane.


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