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

CAS: number 74-98-6

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: Simple asphyxiant

Description of substance: Colorless, odorless gas.

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

Original (SCP) IDLH: 20,000 ppm [LEL]

Basis for original (SCP) IDLH: Propane is a simple asphyxiant and does not present an IDLH hazard at concentrations below its lower explosive limit (LEL). The chosen IDLH is based on the LEL of 21,000 ppm rounded down to 20,000 ppm.

Short-term exposure guidelines: None developed


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

Human data: It has been reported that brief inhalation exposures to 10,000 ppm propane cause no symptoms in humans [Braker and Mossman 1980]. Propane is considered to be a simple asphyxiant [ACGIH 1991].

Revised IDLH: 2,100 ppm [LEL]

Basis for revised IDLH: Based on acute inhalation toxicity data in humans [ACGIH 1991; Braker 1980], a value much greater than 10,000 ppm would have been appropriate. However, the revised IDLH for propane is 2,100 ppm based strictly on safety considerations (i.e., being 10% of the lower explosive limit of 2.1%).


1. ACGIH [1991]. Propane. In: Documentation of the threshold limit values and biological exposure indices. 6th ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, pp. 1286-1287.

2. Braker W, Mossman AL [1980]. Matheson gas data book. 6th ed. Secaucus, NJ: Matheson Gas Products, pp. 615-623.

Page last reviewed: December 4, 2014