With the rapid development of urbanization, the economy and number of vehicles, the urban climate has worsened in recent years, causing serious urban problems including urban heat islands, air pollution and infectious disease transmission. Ventilation is indicated as one of the most effective approaches to solve these problems. Based on the traditional concept of room ventilation, the present work developed a new physical model and lumped mathematical model for urban ventilation, which is the product of both horizontal wind speed and vertical mixing layer height. This urban ventilation model was validated by a case study implemented in the city of Changsha. Both Pearson correlation analysis and principal component analysis (PCA) indicated that the urban heat island intensity and PM10 concentration are significantly negatively correlated with the urban ventilation rate, i.e. urban mixing layer height and wind speed.
