A stack emitting 85 g/s of NO has an effective stack height of 100 m. The wind speed is 3 m/s at 10 m, and it is a cloudy summer day. Estimate ground level NO concentration:
a) directly downwind at a distance of 3 km
b) at the point downwind where NO is a maximum
c) at a point located 2 km downwind and 0.1 km off the downwind axis.