Yellow card cars are not allowed to enter the city. Due to the backward exhaust emission control technology, the exhaust emission of yellow-label vehicles can not meet the European 1 standard, and the emission is 5 to 10 times that of new vehicles. During the "Twelfth Five-Year Plan" period, according to the needs of regional air pollution prevention and control, corresponding traffic control measures were taken throughout the country to limit the area, time, road section or vehicle type of "yellow truck" driving in this city.