May 1994
Immediately Dangerous to Life or Health Concentrations (IDLH)

CAS number: 68476–85–7

NIOSH REL: 1,000 ppm (1,800 mg/m3) TWA

Current OSHA PEL: 1,000 ppm (1,800 mg/m3) TWA

1989 OSHA PEL: Same as current PEL

1993-1994 ACGIH TLV: 1,000 ppm (1,800 mg/m3) TWA

Description of substance: Colorless, noncorrosive, odorless gas when pure.

LEL(propane): 2.1% (10% LEL, 2,100 ppm)

LEL(butane): 1.9% (10% LEL, 1,900 ppm)

Original (SCP) IDLH: 19,000 ppm [LEL]

Basis for original (SCP) IDLH: Because propane is a simple asphyxiant, L.P.G. is also considered to be a simple asphyxiant. L.P.G., therefore, does not present an IDLH hazard at concentrations below its lower explosive limit (LEL). The chosen IDLH, based on the “estimated” LEL for L.P.G. (19,000 ppm), is the concentration above which only the “most protective” respirators are permitted.

Short-term exposure guidelines: None developed


Animal data: None relevant for use in determining the revised IDLH.

Human data: At extremely high concentrations, L.P.G. may cause asphyxia by oxygen displacement [Proctor et al. 1988]. Propane concentrations of 100,000 ppm may cause dizziness within a few minutes [Proctor et al. 1988].

Revised IDLH: 2,000 ppm [LEL]

Basis for revised IDLH: Because L.P.G. may cause asphyxia [Proctor et al. 1988] at concentrations well above the lower explosive limit (LEL), the revised IDLH for L.P.G. is 2,000 ppm based strictly on safety considerations (i.e., being about 10% of the LELs of 1.9% for butane and 2.1% for propane).


1. Proctor NH, Hughes JP, Fischman ML [1988]. Liquified petroleum gas. In: Chemical hazards of the workplace. 2nd ed. Philadelphia, PA: J.B. Lippincott Company, pp. 301, 420-421.

Page last reviewed: December 4, 2014