A reactor in a pesticide plant contains 1000 lb of a liquid mixture of 50% by weight liquid methyl isocyanate (MIC). The liquid is near its boiling point. A study of various release scenarios indicates that a rupture of the reactor will spill the liquid into a boiling pool on the ground. The boiling rate of MIC has been estimated to be 20 lb/min. Evacuation of the population must occur in areas where the vapor concentration exceeds ERPG-3. If the wind speed is 3.4 mph on a clear night, estimate the area downwind that must be evacuated.