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Definition of PACs |
| Acute Exposure Guideline Levels (AEGLs) are defined as follows: AEGL-1 is the airborne concentration (expressed as ppm [parts per million] or mg/m3 [milligrams per cubic meter]) of a substance above which it is predicted that the general population, including susceptible individuals, could experience discomfort, irritation, or certain asymptomatic, nonsensory effects. However, these effects are not disabling and are transient and reversible upon cessation of exposure. AEGL-2 is the airborne concentration (expressed as ppm or mg/m3) of a substance above which it is predicted that the general population, including susceptible individuals, could experience irreversible or other serious, long-lasting, adverse health effects or an impaired ability to escape. AEGL-3 is the airborne concentration (expressed as ppm or mg/m3) of a substance above which it is predicted that the general population, including susceptible individuals, could experience life-threatening health effects or death. Emergency Response Planning Guidelines (ERPGs) are defined as follows: ERPG-1 is the maximum concentration in air below which it is believed nearly all individuals could be exposed for up to one hour without experiencing other than mild transient adverse health effects or perceiving a clearly defined objectionable odor. ERPG-2 is the maximum concentration in air below which it is believed nearly all individuals could be exposed for up to one hour without experiencing or developing irreversible or other serious health effects or symptoms that could impair their abilities to take protective action. ERPG-3 is the maximum concentration in air below which it is believed nearly all individuals could be exposed for up to one hour without experiencing or developing life-threatening health effects. Temporary Emergency Exposure Limits (TEELs) are defined as follows: TEEL-0 is the threshold concentration below which most people will experience no adverse health effects. TEEL-1 -- Same as ERPG-1 (with the exception of the recommended averaging time). TEEL-2 -- Same as ERPG-2 (with the exception of the recommended averaging time). TEEL-3 -- Same as ERPG-3 (with the exception of the recommended averaging time). TEELs are intended for use until AEGLs or ERPGs are adopted for chemicals. It is recommended that, for application of TEELs, the concentration at the receptor point of interest be calculated as the peak 15-minute time-weighted average concentration. It should be emphasized that TEELs are default values, following the published methodology (on SCAPA's web page) explicitly. The only judgment involved is that exercised in the extraction of data that is entered in the Excel Workbook used to automatically calculate the recommended TEELs. |
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