Immediately Dangerous to Life or Health Concentrations (IDLH)
CAS number: 124–38–9

NIOSH REL: 5,000 ppm (9,000 mg/m3) TWA,

30,000 ppm (54,000 mg/m3) STEL

Current OSHA PEL: 5,000 ppm (9,000 mg/m3) TWA

1989 OSHA PEL: 10,000 ppm (18,000 mg/m3) TWA,

30,000 ppm (54,000 mg/m3) STEL

Basis for original (SCP) IDLH: The chosen IDLH is based on the statements by ACGIH [1971] that a 30-minute exposure at 50,000 ppm produces signs of intoxication, and a few minutes of exposure at 70,000 ppm and 100,000 ppm produces unconsciousness [Flury and Zernik 1931]. AIHA [1971] reported that 100,000 ppm is the atmospheric concentration immediately dangerous to life. In addition, Hunter [1975] noted that exposure to 100,000 ppm for only a few minutes can cause loss of consciousness.