Skip directly to search Skip directly to A to Z list Skip directly to navigation Skip directly to site content Skip directly to page options
CDC Home

Abbreviations for IDLH Documentation

May 1994
Immediately Dangerous to Life or Health Concentrations (IDLH)
A1confirmed human carcinogen (ACGIH)
A2suspected human carcinogen (ACGIH)
A3animal carcinogen (ACGIH)
A4not classifiable as a human carcinogen (ACGIH)
A5not suspected as a human carcinogen (ACGIH)
ACGIHAmerican Conference of Governmental Industrial Hygienists
AIHAAmerican Industrial Hygiene Association
CASChemical Abstract Service
CFcorrection factor for LC data
CFRCode of Federal Regulations
EEGLemergency exposure guidance level (NRC)
ERPGemergency response planning guideline (AIHA)
IDLHimmediately dangerous to life or health concentration value
LClethal concentration
LC50concentration causing death in 50%
LCLolowest concentration causing death
LDlethal dose
LD50dosage causing death in 50%
LDLolowest dosage causing death
LELlower explosive limit
mg/kgmilligrams per kilogram of body weight
mg/m3milligrams per cubic meter of air
mmHgmillimeters of mercury (pressure measurement)
mppcfmillions of particles per cubic foot of air
NIOSHNational Institute for Occupational Safety and Health
NRCNational Research Council
OSHAOccupational Safety and Health Administration
PELpermissible exposure limit (OSHA)
ppmparts per million parts of air
RD50concentration producing a 50% decrease in respiratory rate following a 10-minute exposure
RELrecommended exposure limit (NIOSH)
SCPStandards Completion Program (NIOSH/OSHA)
SPEGLshort-term public emergency guidance level (NRC)
STELShort-term exposure limit
TCLolowest concentration resulting in a toxic effect
TDLolowest dose resulting in a toxic effect
TLVthreshold limit value (ACGIH)
TWAtime-weighted average
Contact Us:
  • Page last reviewed: December 4, 2014
  • Page last updated: December 4, 2014 The U.S. Government's Official Web PortalDepartment of Health and Human Services
Centers for Disease Control and Prevention   1600 Clifton Rd. Atlanta, GA 30329-4027, USA
800-CDC-INFO (800-232-4636) TTY: (888) 232-6348 - Contact CDC-INFO