Onsite Exposure Screening Guidelines

DOE-STD-3014-96

APPENDIX A

Basis: Currently, ERPGs have only been defined for 35 chemicals. In

Appendix A of Technical Guidance on Hazards Analysis, the EPA

discusses the options that are available for the definition of the LOC. For

most chemicals, the Immediately Dangerous to Life and Health (IDLH) is

tabulated. The IDLH has been developed by the National Institute for

Occupational Safety and Health (NIOSH) and is defined as "The

maximum concentration of a substance in air from which healthy male

workers can escape without loss of life or irreversible health effects under

conditions of a maximum 30-minute exposure time." EPA recommends

10 percent of the IDLH as an LOC. If neither the IDLH nor the ERPG is

available, it is recommended that the analyst consult an expert

toxicologist.

Occasionally, the question arises as to whether worker exposure limits

such as the Threshold Limit Value (TLV) could be used as LOCs in

emergencies involving the public. The TLV has been developed by the

American Conference of Government Industrial Hygienists (ACGIH) to

limit workplace exposure. ACGIH explicitly advises against using or

applying TLVs outside the workplace.

A.1.2 Onsite Exposure Screening Guidelines. Much thought went into the issue of

whether additional guidelines were required specifically to address the risk to

onsite workers. That is, could there be cases in which more detailed analysis of

aircraft crash scenarios would be desirable even if there no risk to the public? It

was felt that, in the main, there would be no need for guidelines related to worker

safety. The basis for this conclusion is the nature of aircraft crash itself. An

aircraft crash violent enough to cause a release from a facility will result in death

to the occupants of the aircraft with near certainty. Further, the level of damage

at the facility itself would also, with high probability, result in death or serious

injury to occupants of the facility or neighboring areas directly affected by the

crash and associated debris. When one considers these high probability

consequences, exposure to hazardous material release is very unlikely to add

significantly to the workers' overall risk from the accident. In fact, the insights

A-3