To quantify the impact of public transportation on urban air quality, a co-Integration analysis model of public transit and healthy urban air quality was constructed. The annual average concentration of sulfur dioxide is selected as the air quality index, and the share index of public transit by all modes is selected as the public transit index. Unit root tests are performed on the raw data of indexes by DF-GLS test and KPSS test, which are all shown as non-stationary sequences, and after the first difference processing, the data are presented as stationary sequences. A vector error correction model (VECM) is established to analyze the co-integration relationship between public transit of passenger share index and the air quality. Also, a JJ test method is applied to a co-integration test on the long-term equilibrium relationship between the share index of public transit by all modes and the sulfur dioxide air quality index. The result shows that a long-term equilibrium relationship exist between the two indexes. A Granger causality test is further tested, which shows that the share index of public transit by all modes is the Granger cause of the annual average value of sulfur dioxide concentration, while the latter is not the Granger reason of the former.

CICTP