Risk Assessment on Storage and Handling of Highly Toxic …
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Fig. 2 Threat zone (ALOHA software screen shot)
Red
2.5 km (0.6 ppm = ERPG3)
Orange 4.2 km (0.15 ppm = ERPG2)
Yellow 9.7 km (0.01 ppm = ERPG1).
ERPG-3 is the maximum airborne concentration below which people could be
exposed for up to 1 h without experiencing life-threatening health effects.
ERPG-2 is the maximum airborne concentration below which people could be
exposed for up to 1 h without experiencing other serious health effects or symptoms
which could impair an individuals ability to take protective action.