NIOSH Pocket Guide to Chemical Hazards

Silica, amorphous CAS 7631-86-9
SiO2 RTECS VV7310000
Synonyms & Trade Names
Diatomaceous earth, Diatomaceous silica, Diatomite, Precipitated amorphous silica, Silica gel, Silicon dioxide (amorphous)
DOT ID & Guide
Exposure
Limits
NIOSH REL: TWA 6 mg/m3
OSHA PEL†: TWA 20 mppcf (80 mg/m3/%SiO2)
IDLH 3000 mg/m3 See: 7631869 Conversion
Physical Description
Transparent to gray, odorless powder. [Note: Amorphous silica is the non-crystalline form of SiO2.]
MW: 60.1
BP: 4046°F
MLT: 3110°F
Sol: Insoluble
VP: 0 mmHg (approx)
IP: NA

Sp.Gr: 2.20
Fl.P: NA
UEL: NA
LEL: NA

Noncombustible Solid
Incompatibilities & Reactivities
Fluorine, oxygen difluoride, chlorine trifluoride
Measurement Methods
NIOSH 7501
See: NMAM or OSHA Methods
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

Important additional information about respirator selection
Respirator Recommendations NIOSH
Up to 30 mg/m3: (APF = 5) Any dust and mist respirator
Up to 60 mg/m3: (APF = 10) Any dust and mist respirator except single-use and quarter-mask respirators/(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 dust and mist filter
Up to 300 mg/m3: (APF = 50) Any air-purifying, full-facepiece respirator with a high-efficiency particulate filter/(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 a high-efficiency particulate filter/Any appropriate escape-type, self-contained breathing apparatus
Exposure Routes inhalation, skin and/or eye contact
Symptoms Irritation eyes, pneumoconiosis
Target Organs Eyes, respiratory system
See also: INTRODUCTION

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