An Econometric Approach toward Identifying the Relationship between Vehicular Traffic and Air Quality in Beijing
利用小时级数据重新检验北京交通拥堵与空气质量的因果关系，发现33%到57%的空气污染来自车辆排放，且存在非线性特征，提示政策应聚焦最拥堵区域。
Earlier studies that evaluated the impact of vehicular emissions on urban air quality often reached mixed conclusions, providing little guidance to city planners seeking solutions to the ever-growing problem of air pollution. In this paper, we combine the strengths of earlier studies with hourly-level data to reexamine the causal relationship between traffic congestion and ambient air quality in Beijing. We find that around 33% to 57% of ambient air pollution in Beijing can be attributed to vehicular emissions. However, this average figure is masked by nonlinearity, suggesting that policy makers should focus their efforts on alleviating areas with heaviest congestion to improve air quality.