Silica, crystalline (as respirable dust)
Synonyms & Trade Names
Cristobalite, Quartz, Tridymite, TripoliFormula
SiO₂Conversion
Exposure Limits
NIOSH REL
Ca TWA 0.05 mg/m3 See Appendix AOSHA PEL
See Appendix C (Mineral Dusts) See Appendix GPhysical Description
Colorless, odorless solid. [Note: A component of many mineral dusts.]Molecular Weight
60.1Boiling Point
4046°FMelting Point
3110°FSolubility
InsolubleVapor Pressure
0 mmHg (approx)Ionization Potential
NASpecific Gravity
2.66Flash Point
NAUpper Exposive Limit
?Lower Explosive Limit
?Incompatibilities & Reactivities
Powerful oxidizers: fluorine, chlorine trifluoride, manganese trioxide, oxygen difluoride, hydrogen peroxide, etc.; acetylene; ammoniaExposure Routes
inhalation, skin and/or eye contactSymptoms
Cough, dyspnea (breathing difficulty), wheezing; decreased pulmonary function, progressive resp symptoms (silicosis); irritation eyes; [potential occupational carcinogen]Target Organs
Eyes, respiratory systemCancer Site
[in animals: lung cancer]Personal 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 0.5 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.
Up to 1.25 mg/m3:
(APF = 25) Any powered, air-purifying respirator with a high-efficiency particulate filter.
(APF = 25) Any supplied-air respirator operated in a continuous-flow mode
Up to 2.5 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 powered, air-purifying respirator with a tight-fitting facepiece and a high-efficiency particulate filter
Up to 25 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
- 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