Dow Chemical Exposure Index
A flowchart of the CEI procedure is shown in the Figure. The procedure begins with a definition of possible release incidents. This includes releases from pipes, hoses, pressure relief devices relieving directly to the atmosphere, vessels and tanks overflows and spills. Detailed guidelines can be found in the CEI Guide. The incidents are used with a number of simplified source models provided in the Dow Guide to estimate the release rate of material. The ERPGs are then used with a simplified dispersion model to determine the CEI value and downwind hazard distances resulting from the release.
The Emergency Response Planning Guideline (ERPG) values are published by the American Industrial Hygiene Association (AIHA). These values are intended to provide estimates of concentration ranges where one reasonably might anticipate observing adverse effects as described in the definitions for ERPG-1, ERPG-2, and ERPG-3 as a consequence of exposure to the specific substance.
• The ERPG-1 is the maximum airborne concentration below which it is believed that nearly all individuals could be exposed for up to 1 hr without experiencing other than mild transient adverse health effects or perceiving a clearly defined, objectionable odor.
• The ERPG-2 is the maximum airborne concentration below which it is believed that nearly all individuals could be exposed for up to 1-hr without experiencing or developing irreversible or other serious health effects or symptoms which could impair an individual's ability to take protective action.
• The ERPG-3 is the maximum airborne concentration below which it is believed that nearly all individuals could be exposed for up to 1-hr without experiencing or developing life-threatening health effects.
ERPG values for selected chemicals are shown in the Table. Note that these values are being constantly updated.