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Emergency Response Planning Guidelines (ERPGs)
ERPGs are guidelines designed to anticipate health effects from exposure to toxic chemicals.
This page discusses the following topics:
What are ERPGs?
ERPGs estimate the concentrations at which most people will begin to experience health effects if they are exposed to a toxic chemical for 1 hour. (Sensitive members of the public--such as old, sick, or very young people--are not covered by these guidelines and they may experience adverse effects at concentrations below the ERPG values.) A chemical may have up to three ERPG values, each of which corresponds to a specific tier of health effects.
The three ERPG tiers are defined as follows:
How are ERPGs chosen?
ERPGs are developed by the Emergency Response Planning committee of the American Industrial Hygiene Association (AIHA). The ERPG guidelines are clearly defined and based on extensive, current data. The rationale for selecting each value is explained, and other pertinent information is also provided. Each guideline identifies the substance, its chemical and structural properties, animal toxicology data, human experience, existing exposure guidelines, the rationale behind the selected value, and a list of references. To find out more about the ERPG development process, select the link titled ERPG Program at the bottom of this page.
What substances have ERPGs?
As of mid-2007, just over 120 chemicals have ERPGs. To see the current list of substances that have ERPGs, select the link titled ERPG Chemicals at the bottom of this page. You can also search for a specific substance on the CAMEO Chemicals site (by selecting the link at the bottom of this page) to find response recommendations and chemical data (including ERPGs).
How should ERPGs be used?
ERPGs should be used to help protect the public when AEGLs are not available and there has been a chemical release that is short-term in duration.
ERPGs estimate how nearly all of the public (except for sensitive individuals) would react to a release of this nature, so they can be used to identify areas where a hazard exists if the toxic gas concentration is exceeded for the specified exposure duration. For example, in areas with concentrations above the ERPG-1, most people would detect the chemical and may experience temporary, mild effects. On the other hand, in areas with concentrations above the ERPG-2, most people would experience significant, but not life-threatening, health effects.
These guidelines are focused on one period of time: 1 hour. Exposure in the field may be longer or shorter. However, AIHA strongly advises against trying to extrapolate ERPG values to longer periods of time.
ERPGs should not be used as:
- Guidelines for workers who are routinely exposed to chemicals for longer durations. In such cases, you should use workplace exposure limits (such as the Threshold Limit Value) because they contain safety factors specific to this type of exposure.
- Guidelines for members of the public who are exposed to background chemical releases for longer durations. In these types of air quality issues, values such as the National Ambient Air Quality Standards (NAAQS) should be used rather than emergency response guidelines.
How does ALOHA use ERPGs?
In ALOHA, you can choose ERPGs as your Levels of Concern (LOCs) when modeling a toxic chemical release--if ERPGs have been defined for that chemical. (A toxic LOC is the value above which the toxic gas concentration might be high enough to harm people.) ALOHA allows you to specify up to three toxic LOCs. So, you can choose the ERPG-1, ERPG-2, and ERPG-3 values to generate a threat zone plot where yellow, orange, and red zones indicate areas where the those values were exceeded at some point after the chemical release began. (To determine how long the LOC was exceeded at a particular location, read the Ask Dr. ALOHA article on working with the concentration graph.)
For chemicals defined under the ERPG classification system, ALOHA will provide the ERPG values as the default toxic LOCs until final AEGL values are established.
Where else can I find information on ERPGs?
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- ERPG Program Read all about ERPGs on this AIHI site, which contains a list of current ERPGs and details about ERPG development. [leaves OR&R site]
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- ERPG Chemicals See the current list of chemicals with ERPGs and the list of chemicals under consideration or review by the AIHA Emergency Response Planning Committee. (Document format: PDF, size: 53.2 K) [leaves OR&R site]
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- CAMEO Chemicals Search the CAMEO chemical database online and find ERPGs for specific chemicals. At this separate Office of Response and Restoration site, you can also print customized reports with response recommendations and find out how chemicals would react if they mixed. [leaves OR&R site]
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