Silica, amorphous
Synonyms & Trade Names
Diatomaceous earth, Diatomaceous silica, Diatomite, Precipitated amorphous silica, Silica gel, Silicon dioxide (amorphous)Exposure Limits
NIOSH REL
TWA 6 mg/m3OSHA PEL
TWA 20 mppcf (80 mg/m3/%SiO2) See Appendix C (Mineral Dusts) See Appendix GPhysical Description
Transparent to gray, odorless powder. [Note: Amorphous silica is the non-crystalline form of SiO2.]Molecular Weight
60.1Boiling Point
4046°FMelting Point
3110°FSolubility
InsolubleVapor Pressure
0 mmHg (approx)Ionization Potential
NASpecific Gravity
2.20Flash Point
NAUpper Exposive Limit
NALower Explosive Limit
NAIncompatibilities & Reactivities
Fluorine, oxygen difluoride, chlorine trifluorideExposure Routes
inhalation, skin and/or eye contactSymptoms
irritation eyes, pneumoconiosisTarget Organs
Eyes, respiratory systemPersonal Protection/Sanitation
(See protection codes)Skin:No recommendation
Eyes:No recommendation
Wash skin:No recommendation
Remove:No recommendation
Change:No recommendation
Respirator Recommendations
NIOSH
Up to 30 mg/m3:
(APF = 5) Any quarter-mask respirator.
Click here for information on selection of N, R, or P filters.
Up to 60 mg/m3:
(APF = 10) Any particulate respirator equipped with an N95, R95, or P95 filter (including N95, R95, and P95 filtering facepieces) except quarter-mask respirators. The following filters may also be used: N99, R99, P99, N100, R100, P100.
Click here for information on selection of N, R, or P filters.
(APF = 10) Any supplied-air respirator
Up to 150 mg/m3:
(APF = 25) Any supplied-air respirator operated in a continuous-flow mode
(APF = 25) Any powered, air-purifying respirator with a high-efficiency particulate filter.
Up to 300 mg/m3:
(APF = 50) Any air-purifying, full-facepiece respirator with an N100, R100, or P100 filter.
Click here for information on selection of N, R, or P filters.
(APF = 50) Any supplied-air respirator that has a tight-fitting facepiece and is operated in a continuous-flow mode
(APF = 50) Any powered, air-purifying respirator with a tight-fitting facepiece and a high-efficiency particulate filter
(APF = 50) Any self-contained breathing apparatus with a full facepiece
(APF = 50) Any supplied-air respirator with a full facepiece
Up to 3000 mg/m3:
(APF = 1000) Any supplied-air respirator operated in a pressure-demand or other positive-pressure mode
Emergency or planned entry into unknown concentrations or IDLH conditions:
(APF = 10,000) Any self-contained breathing apparatus that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode
(APF = 10,000) Any supplied-air respirator that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode in combination with an auxiliary self-contained positive-pressure breathing apparatus
Escape:
(APF = 50) Any air-purifying, full-facepiece respirator with an N100, R100, or P100 filter.
Click here for information on selection of N, R, or P filters.
Any appropriate escape-type, self-contained breathing apparatus
See also
INTRODUCTION- Page last reviewed:April 11, 2016
- Page last updated:April 11, 2016
- Content source:
- National Institute for Occupational Safety and Health (NIOSH) Education and Information Division