Abstract: To explore the reasons for the difference in air demand in the ventilation standards of highway tunnels in China and abroad, and solve the current difficulties in the precise design of highway tunnel ventilation, the China′s tunnel ventilation design standard of 〖WT５《TNR#I》〗Road Tunnel Ventilation Design Rules〖WT５《TNR》〗 (JTG /T D70/2022014) and the 〖WT５《TNR#I》〗Vehicle Emissions and Air Demand for Ventilation〖WT５《TNR》〗 2019 by the WorldRoadAssociation are taken as study objects, the calculation methods of freshair volume required for diluting pollutants of motor vehicles in tunnels are used to calculate the freshair volume required for the shortterm(2035) and longterm(2045) of diluting CO, NO2, and VI under six conditions such as 80 km/h, 60 km/h, 40 km/h, 30 km/h, 20 km/h (full block), and 10 km/h (local block), by taking the Yangtze river tunnel in Jiangsu province, China as an example. The results reveal the following:  (1) The difference in two calculation methods results in the difference in calculation results. The design freshair volume required for diluting pollutants calculated by Chinese standards is 3.35 times higher than that by foreign standards. The difference of CO baseline emissions of motor vehicles in China and abroad is the reason for the large difference in the air volume required to dilute CO, and the impact of NO2 on the freshair volume of tunnels has gradually exceeded that of CO. (2) The result of calculating the freshair volume required for VI dilution using Chinese standards shows that it is significantly affected by the design concentration value of VI and the vehicle density under low vehicle speed conditions. (3) With the gradual strictness of motor vehicle exhaust emission standards and the emergence of new energy vehicles, in order to adapt to the characteristics of motor vehicle exhaust emissions in China, the factors to be considered in the new baseline emissions need to be increased.

Key words:  , highway tunnel, motor vehicle pollutants, air demand calculation, baseline emission