NIOSH Publication No. 2005-151:

NIOSH Pocket Guide to Chemical Hazards

September 2005

Calcium oxide

CAS
1305-78-8

CaO

RTECS
EW3100000
Synonyms & Trade Names

Burned lime, Burnt lime, Lime, Pebble lime, Quick lime, Unslaked lime
DOT ID & Guide
1910 / 157

Exposure
Limits

NIOSH REL: TWA 2 mg/m3
OSHA PEL: TWA 5 mg/m3
IDLH
25 mg/m3 See: 1305788
Conversion
Physical Description
White or gray, odorless lumps or granular powder.
MW: 56.1
BP: 5162°F
MLT: 4662°F
Sol: Reacts
VP: 0 mmHg (approx)
IP: NA

Sp.Gr: 3.34
Fl.P: NA
UEL: NA
LEL: NA

Noncombustible Solid, but will support combustion by liberation of oxygen.
Incompatibilities & Reactivities

Water (liberates heat), fluorine, ethanol [Note: Reacts with water to form calcium hydroxide.]
Measurement Methods
NIOSH 7020, 7303; OSHA ID121
See: NMAM or OSHA Methods
Personal Protection & Sanitation
(See protection)
Skin: Prevent skin contact
Eyes: Prevent eye contact
Wash skin: When contaminated/Daily
Remove: When wet or contaminated
Change: Daily
Provide: Eyewash, Quick drench
First Aid
(See procedures)
Eye: Irrigate immediately
Skin: Water flush immediately
Breathing: Respiratory support
Swallow: Medical attention immediately
Respirator Recommendations
NIOSH
Up to 10 mg/m3:
(APF = 5) Any quarter-mask respirator. Click here for information on selection of N, R, or P filters.
Up to 20 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 25 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
(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 self-contained breathing apparatus with a full facepiece
(APF = 50) Any supplied-air respirator with a full facepiece
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
Important additional information about respirator selection
Exposure Routes
inhalation, ingestion, skin and/or eye contact
Symptoms
Irritation eyes, skin, upper respiratory tract; ulcer, perforation nasal septum; pneumonitis; dermatitis
Target Organs
Eyes, skin, respiratory system
See also: INTRODUCTION   See ICSC CARD: 0409