Question

A simple way to model air pollution over a city is to use box model that assumes complete mixing and limited capability for the pollution to disperse laterally.A town having an inversion layer 500m above the ground is located in a valley with an average width and length of 5 and 10km,respectively.Clean air is blowing into the box along the valley with a speed of 3m/sec.An accidental spill of 5000kg of a hazardous contaminant happens at the center of this town.Before the response team succeeds to control the situation,1000kg of this toxic material evaporates and mixes with the air.The response team issues a warning asking everybody to stay indoor to prevent any exposure.This toxic contaminant naturally degrades with a reaction rate k=0.41/d.

a.If it is safe to go out when the concentration reduces below 0.01mg/m3, how long the residents should stay indoor until the problem is resolved?

b.What happens if the wind speed drops to 1m/sec?

c.What is the contribution from degradation?

Answer 1

stop using factories that produce polluted air