(b) Compute the path of the puff and use the location of the puff's center to compute the dispersion parameters for the puff σ y and σ z at each point in the puff's path based on the wind speed and stability class. (c) Compute the concentration contribution of the given puff at the sensor locations using equation ( ). Continue to compute the concentration contribution of the given puff by marching the puff in time by a specified timestep ∆t until the puff is discarded when an early stop criterion is satisfied (either based on puff lifetime or distance from the area of interest). 3. Sum the concentration contribution of all puffs to obtain the total concentration prediction at each sensor location, see equation (3).