Mobile source pollution is one of the major reasons for the deterioration of air quality in the metropolitan area and the key point which the environmental-protection and traffic authorities focus on. Besides, emitting the black smoke from diesel vehicles is most series problem blamed by citizens. In order to improve the emission by diesel vehicles, the Environmental Protection Administration (EPA) has implemented not only, irregular inspections, but also enhance the control measures for diesel vehicles. For example, assist Tier-1 to Tier-3 heavy-duty diesel vehicles (HDDVs) to be replaced for new ones, install air pollution control equipment or repair fuel injection system, and it has formulated annual targets for achievement. By the end of 2022, EPA will assist as many as 44,000 Tier-1 to Tier-3 HDDVs to improve pollution. It is expected that these efforts can reduce PM2.5 by approximately 1,635 metric tons, and NOx 17,438 metric tons.
In 2019, there are 9,186 Tier-1 to Tier-3 HDDVs have been eliminated. Among the applications for subsidies, include purchasing new or used vehicles, eliminating Tier-1 to Tier-3 HDDVs and transferring for new vehicles, totaling 8,430 cases. In addition, this plan would also help EPA to officially approve the subsidy eligibility for nine imported and two domestic diesel particulate filter (DPF) vendor. Furthermore, statistics have showed that the smoke improvement rate by HDDVs after installing DPF can reach as much as more than 90%.
This plan would also help EPA to revise the "Smoke Opacity Testing Methods and Procedures of Diesel Vehicles" and the focus of amendment is that if the opacity of first test result is lower than the threshold value, it will be considered eligible, and don’t need to conduct second or third test. The purpose of the amendment is to encourage owners of diesel vehicles to actively implement maintenance, which should help reduce testing time by about 25%. Besides, to make it simpler and more convenient for the general public, the EPA has abolished previous measure of reflection-type (pollution degree) detection method using filter.
During the period of the plan, nationwide correlation test of diesel emission testing stations has been finished well, only one inspection line was found to exceed the control range, showing that the quality of testing stations for diesel vehicles is favorable. Moreover, experts and scholars were invited to handle the evaluation of diesel vehicles (including testing stations for diesel vehicle) in various counties and cities. As compared to the previous results, the number of cities and counties with outstanding performance are found to have increased testing stations from 3 to 9 stations, indicating that the implementation quality by environmental protection bureaus in each county and city has improved significantly. Finally, the statistics of the past six years shows that through irregular inspection of diesel vehicles, the country-wide disqualification rate dropped from 6.1% to 4.4%, indicating emission by diesel vehicles has improved year by year.
