**4. Adding meteorological factors**

The ambient air pollution levels are mainly modulated by meteorological conditions [9, 17]. Consequently, considering these parameters in a model should improve the prediction of the concentration of fine particulate matter. Since the required equipment to proceed with the recording of these data is significantly cheaper than the air quality sensors, we present models that can predict the level of PM2.5 from the selected meteorological features as follows: solar radiation (SR), temperature (T), pressure (P), precipitation (rain), relative humidity (RH), wind speed (WS), and wind direction (WD).
