# NIOSH Pocket Guide to Chemical Hazards
Silica, crystalline (as respirable dust) | CAS 14808-60-7
SiO2 | RTECS VV7330000
Synonyms & Trade Names Cristobalite, Quartz, Tridymite, Tripoli | DOT ID & Guide
Exposure Limits | NIOSH REL: Ca TWA 0.05 mg/m3 See Appendix A
OSHA PEL: Crystalline Quartz (respirable): TWA 250 mppcf/(%SiO2 +5); TWA 10 mg/m3/(%SiO2 + 2) Quartz (total dust): TWA 30 mg/m3/(%SiO2 + 2) Cristobalite: Use ½ the value calculated from the count or mass formulae for quartz. Tridymite: Use ½ the value calculated from the formulae for quartz.
IDLH Ca [25 mg/m3 (cristobalite, tridymite); 50 mg/m3 (quartz, tripoli) | Conversion
Physical Description Colorless, odorless solid. [Note: A component of many mineral dusts.]
MW: 60.1 | BP: 4046°F | MLT: 3110°F | Sol: Insoluble
VP: 0 mmHg (approx) | IP: NA |  | Sp.Gr: 2.66
Fl.P: NA | UEL: NA | LEL: NA |
Noncombustible Solid
Incompatibilities & Reactivities Powerful oxidizers: fluorine, chlorine trifluoride, manganese trioxide, oxygen difluoride, hydrogen peroxide, etc.; acetylene; ammonia
Measurement Methods NIOSH 7500, 7601, 7602; OSHA ID142
Personal Protection & Sanitation Skin: No recommendation Eyes: No recommendation Wash skin: No recommendation Remove: No recommendation Change: No recommendation | First Aid (See procedures) Eye: Irrigate immediately Breathing: Fresh air
Respirator Recommendations NIOSH Up to 0.5 mg/m3: (APF = 10 ) Any air-purifying respirator with a high-efficiency particulate filter 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 a high-efficiency particulate filter/(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 a high-efficiency particulate filter/Any appropriate escape-type, self-contained breathing apparatus
Exposure Routes inhalation, skin and/or eye contact
Symptoms Cough, dyspnea (breathing difficulty), wheezing; decreased pulmonary function, progressive respiratory symptoms (silicosis); irritation eyes; [potential occupational carcinogen]
Target Organs Eyes, respiratory system Cancer Site [in animals: lung cancer]
See also: INTRODUCTION