In the Pasquill-Gifford puff model, what happens to the concentration at a fixed distance downwind if the wind speed is doubled?

In the Pasquill-Gifford puff model, the concentration of a pollutant at a fixed downwind distance is inversely related to the wind speed. When wind speed increases, the dispersion of the pollutant increases as well, meaning that the contaminant is spread out over a larger area in a shorter time.

Doubling the wind speed will result in a stronger horizontal transport of the pollutant away from the source. As the pollutants are dispersed over a greater distance more rapidly, the concentration of the substance at a fixed downwind point decreases.

Thus, the correct understanding is that if the wind speed is doubled, the concentration at that fixed distance will be reduced by a factor of 2. This highlights the relationship between wind speed and pollutant concentration in the model, emphasizing that faster wind speeds lead to lower concentrations at a given distance from the source.