Do driving restriction policies effectively alleviate smog pollution in China?

China has become one of the countries with the most severe smog pollution, especially in winter. Many local governments had to take various measures to combat the smog. The driving restriction is one of the policies being widely implemented throughout the country, but the actual effect has been controversial. Over 30 cities in China adopted the driving restriction policy in winter specifically in recent years. In this study, regression discontinuity (RD) method is applied to 16 cities to study whether the policy was effective or not and to find out the reason behind. It is found that (1) the effect has shown differences in different cities, in Cangzhou, Linfen and Shijiazhuang, the policy was effective on winter smog control, while it was ineffective in Luoyang, Tangshan, Xinyang and Zhoukou. (2) High proportion of secondary industry in GDP and inconvenient public transport system has inhibitory effect on the effectiveness of the driving policy. (3) Population density, GDP, the proportion of urban green area and driving restriction intensity have no significant impact on the effectiveness of the driving restriction policy. (4) In terms of meteorological factors, average temperature, rainfall, wind speed and air pressure have a negative impact on PM2.5, while humidity has a positive impact on PM2.5.