General
idlh
What does idlh mean?
Immediately Dangerous to Life or Health. Any atmosphere that would either kill you, do irreversible damage, or stop you escaping under your own power within 30 minutes. Triggers the two-in/two-out rule and mandatory SCBA.
"Meter pegged on CO at the doorway — IDLH, nobody goes in without a pack and a partner."
Origin
Defined by NIOSH and codified in OSHA respiratory-protection standard 1910.134. Each chemical has a published IDLH concentration.
Frequently asked questions
What does IDLH mean?
It refers to an atmosphere that will kill or maim you if you breathe it without SCBA (self-contained breathing apparatus).
How do you use IDLH in a sentence?
A firefighter might say 'That's an IDLH atmosphere — nobody goes in without air'.
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