In September 2016 NIOSH published revised IDLH value for nine (9) hazardous materials.
Immediately Dangerous to Life or Health (IDLH) Value Profile: Iron Pentacarbonyl
http://www.cdc.gov/niosh/docs/2016-166/default.html
Immediately Dangerous to Life or Health (IDLH) Value Profile: Acrylonitrile
http://www.cdc.gov/niosh/docs/2016-167/default.html
Immediately Dangerous to Life or Health (IDLH) Value Profile: HCFC-141B
http://www.cdc.gov/niosh/docs/2016-168/default.html
Immediately Dangerous to Life or Health (IDLH) Value Profile: Chloroacetyl Chloride
http://www.cdc.gov/niosh/docs/2016-169/default.html
Immediately Dangerous to Life or Health (IDLH) Value Profile: Chlorine Pentafluoride
http://www.cdc.gov/niosh/docs/2016-170/default.html
Immediately Dangerous to Life or Health (IDLH) Value Profile: Furan
http://www.cdc.gov/niosh/docs/2016-171/default.html
Immediately Dangerous to Life or Health (IDLH) Value Profile: Hexafluoracetone
http://www.cdc.gov/niosh/docs/2016-172/default.html
Immediately Dangerous to Life or Health (IDLH) Value Profile: n-Butyl acrylate
http://www.cdc.gov/niosh/docs/2016-173/default.html
Immediately Dangerous to Life or Health (IDLH) Value Profile: Butane
http://www.cdc.gov/niosh/docs/2016-174/default.html
Learn more about NIOSH IDLH values: http://www.cdc.gov/niosh/idlh/idlhintr.html