IDLH

29 CFR 1910.120 identifies immediately dangerous to life or health (IDLH) as "an atmospheric concentration of any toxic, corrosive, or asphyxiant substance that poses an immediate threat to life or would interfere with an individual's ability to escape from a dangerous atmosphere."

Determining the IDLH concentration is one of the main aspects of risk identification; direct-reading instruments give real-time (or near real-time) measurements and come in many forms, each with a specific monitoring purpose. Laboratory analysis is also an option (although it is not time-friendly).

Remember: Risk identification is ongoing. Employers determine IDLH concentrations through the following:

• Initial entry inspection (preliminary survey)
• Detailed survey inspection (upon entering the site)
• Periodic monitoring

To know if the detected levels of chemicals are IDLH after using direct-reading instruments, employers may consult the OSHA Occupational Chemical Database. The database compiles information from agencies and government organizations and provides the following information:

• Chemical identification and physical properties
• Exposure limits
• Sampling information

Users can search for the chemical by its chemical name or Chemical Abstracts Service (CAS) number. Users can opt to view all chemicals with PELs, carcinogenic classifications, or IDLH values.

Employers may also consult 29 CFR 1910.1000 Table Z-1 (titled Limits for Air Contaminants), Table Z-2 (titled Toxic and Hazardous Substances), and Table Z-3 (titled Mineral Dusts).

To learn more about HAZWOPER visit our HAZWOPER 40 Hour Online Training web page.