NIOSH Publication No. 2005-151:

NIOSH Pocket Guide to Chemical Hazards

September 2005

Propylene oxide



Synonyms & Trade Names

1,2-Epoxy propane; Methyl ethylene oxide; Methyloxirane; Propene oxide; 1,2-Propylene oxide
DOT ID & Guide
1280 / 127P


NIOSH REL: Ca See Appendix A
OSHA PEL: TWA 100 ppm (240 mg/m3)
Ca [400 ppm] See: 75569
1 ppm = 2.38 mg/m3
Physical Description
Colorless liquid with a benzene-like odor. [Note: A gas above 94°F.]
MW: 58.1
BP: 94°F
FRZ: -170°F
Sol: 41%
VP: 445 mmHg
IP: 9.81 eV

Sp.Gr: 0.83
Fl.P: -35°F
UEL: 36%
LEL: 2.3%

Class IA Flammable Liquid: Fl.P. below 73F and BP below 100F.
Incompatibilities & Reactivities

Anhydrous metal chlorides; iron; strong acids, caustics & peroxides [Note: Polymerization may occur due to high temperatures or contamination with alkalis, aqueous acids, amines & acidic alcohols.]
Measurement Methods
NIOSH 1612; OSHA 88
See: NMAM or OSHA Methods
Personal Protection & Sanitation
(See protection)
Skin: Prevent skin contact
Eyes: Prevent eye contact
Wash skin: When contaminated
Remove: When wet (flammable)
Change: No recommendation
Provide: Quick drench
First Aid
(See procedures)
Eye: Irrigate immediately
Skin: Water flush immediately
Breathing: Respiratory support
Swallow: Medical attention immediately
Respirator Recommendations
At concentrations above the NIOSH REL, or where there is no REL, at any detectable concentration:
(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
(APF = 50) Any air-purifying, full-facepiece respirator (gas mask) with a chin-style, front- or back-mounted canister providing protection against the compound of concern/Any appropriate escape-type, self-contained breathing apparatus
Important additional information about respirator selection
Exposure Routes
inhalation, ingestion, skin and/or eye contact
Irritation eyes, skin, respiratory system; skin blisters, burns; [potential occupational carcinogen]
Target Organs
Eyes, skin, respiratory system

Cancer Site
[in animals: nasal tumors]
See also: INTRODUCTION   See ICSC CARD: 0192