A power plant emits 300 kg/h of SO2 into a neutral atmosphere with a wind speed of 2 m/s. The atmospheric dispersions are assumed to be 100 m (along the y-axis) and 30 m (along the vertical direction). What will be the ground level concentration of SO2, expressed in micrograms per cubic meter, if the town is 2 km off the plume centerline and the plant has a stack that produces an effective stack height of 20 m? What will be the ground level concentration if the power plant installs a 150-m stack?