11/13/2022
This is OSHA Interpretation Letter and it constitutes OSHA's interpretation of the requirements for the Hazardous Waste Operations Emergency Response standard (29 CFR 1910.120).
"It is not the intent of the Agency to define an emergency condition in terms of an arbitrary quantity of material released due to the diversity of workplace conditions, conditions of chemical use, and types of chemicals used.
When, as a consequence of a release of a hazardous substance the following conditions, or similar conditions, may develop, such situations would normally be considered emergency situations requiring an emergency response effort:
High concentrations of toxic substances.
Situation that is life or injury threatening.
Imminent Danger to Life and Health (IDLH) environments.
Situation that presents an oxygen deficient atmosphere.
Condition that poses a fire or explosion hazard.
Situation that required an evacuation of the area.
A situation that requires immediate attention because of the danger posed to employees in the area.
Incidental releases that can be handled safely by employees in the immediate area, without the aid of a coordinated response effort from employees outside the area, would not be considered an emergency incident under 29 CFR 1910.120.
Employers, who intend to evacuate employees from the danger zone when an emergency situation occurs and who do not expect employees to assist in handling the emergency, are exempt from developing an emergency response plan provided an emergency action plan is developed in accordance with 29 CFR 1910.38(a).
The intent of the standard is to protect employees from exposure to the health and physical hazards of hazardous substances associated with hazardous waste operations and emergency response activities. Absent testing data on the mixture as a whole, the hazards of a mixture containing hazardous substances would be expected to be treated as a hazardous substance for compliance purposes.
The determination of how much of a solvent mixture spill (containing 10-100 ppm of benzene) would represent an emergency, is dependent upon many factors. It is not possible to respond to your specific question based on the information provided. However, in general, a theoretical concentration for each component part can be calculated based on the quantity of solvent spilled, the percentage by weight of volume of each component, and the size of the spill area. In the event the components of a mixture pose an additive effect, the TLV for the mixture can be calculated. Dependent upon the quantity of a solvent expected to be released and the size of the spill area, a determination could then be made as to whether or not such a concentration would result.
When the concentration of the mixture as a whole or the concentration of the component parts poses a condition previously described, an emergency situation would be anticipated requiring an emergency response".