*2.5. Selection of Indicators for the Evaluation of "Pollutants–Wind Environment"*

The "wind speed ratio" [23] evaluation index refers to the ratio of the wind speed at the actual selected location to the incoming wind speed on that day, which is often used to reflect the degree of influence of different areas or buildings on the wind speed, as a way to evaluate the condition of the wind environment in the region. "Pollutant concentration ratio" means the ratio of the concentration of pollutants in different areas to the concentration of incoming pollutants, which is used to quantify the relative level of pollution in a local area.

$$VR\_w = \frac{V\_p}{V\_\infty} \tag{3}$$

$$\mathcal{C}R\_p = \frac{\mathcal{C}\_p}{\mathcal{C}\_{\infty}}\tag{4}$$

In Equations (3) and (4), *VRw* is the wind speed ratio; *Vp* is the wind speed value at a certain height in a region (m/s); *CRp* is the pollutant concentration ratio; *Vp* is the average concentration of pollutants at a certain height in a region (μg/m3); *V*<sup>∞</sup> is the average concentration of incoming pollutants in a region (μg/m3).
