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Emergency Response Planning Guidelines (ERPG) |
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Acronyms
/ Definitions |
As defined by The American Industrial Hygiene Association (AIHA), ERPGs provide estimates for concentration ranges ‘where a person may reasonably anticipate observing adverse effects as a consequence of exposure to the chemical in question’. ERPG LevelsThree ERPG values are provided for each of the substances that have been researched. They are:ERPG-3The maximum airborne concentration below which it is believed nearly all individuals could be exposed for up to one hour without experiencing or developing life-threatening health effects. ERPG-2The maximum airborne concentration 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 an individual’s ability to take protective action. ERPG-1The maximum airborne concentration 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 values for some widely used chemicals are provided in Table 1. Additional chemicals are listed by the American Industrial Hygienists Association.
Table 1
ERPG Values (ppm by volume)
A key feature of all ERPG levels is that exposure is measured over a period of one hour. In practice, a worker who is exposed to one of these chemicals is not going to stay in the same place for an hour; he or she is going to move to a safe place (assuming that he is conscious and mobile). LimitationsHuman responses do not occur at precise exposure levels but can extend over a wide range of concentrations. The values derived for ERPGs should not be expected to protect everyone but should be applicable to most individuals in the general population. In particular, industrial workers are generally quite healthy and they know what to do and where to go in the event of an emergency. Hence there is not usually a justification for using very conservative exposure limit values for short-term exposure to a toxic gas release. For this reason the ERPG-2 value can be used rather than the more conservative ERPG-1 level. If members of the public could suffer short-term exposure effects then the ERPG-1 value would be used, particularly if some of the public could be in ill health, or if they could have trouble in evacuating the affected area. On the other hand, in the general public there will be hypersensitive individuals who will show adverse responses at exposure concentrations far below levels where most individuals normally would respond. |
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