Traceability Discussion on China VI Standard Automobile Exhaust Emission Detection

As the number of vehicles in China continues to increase, pollution from automobile exhaust has become increasingly severe. To control environmental pollution, China promulgated the "Air Pollution Prevention and Control Law of the People's Republic of China" as early as 1987. In 2013, the European Union released the Euro VI standard (EURO VI A-VI D). China, drawing on the Euro VI standard and considering its national conditions, issued GB 18352.6-2016 "Limits and Measurement Methods for Emissions from Light-Duty Vehicles (China 6)" (hereinafter referred to as the China VI standard) in 2016, which was implemented in phases starting from January 2020. This standard has set new requirements for the regulation and quality control traceability of automobile exhaust emissions. This article compares the differences in emission quality control requirements between the China V and China VI standards, and introduces the measurement methods for updated emission-limited pollutants in the China VI standard, including carbon monoxide (CO), nitrogen oxides (NOx), non-methane hydrocarbons (NMHC), nitrous oxide (N₂O), particle number (PN), and particulate matter (PM). It also describes China's exhaust emission detection and traceability technology from the aspects of developing national gas reference materials, establishing measurement standards, and founding national automobile testing centers. The analysis shows that existing capabilities and technical levels cannot meet some emission detection requirements in the China VI standard. The article proposes areas in current traceability technology that need further optimization, such as the condensation particle counter in particle number (PN) measurement instruments. It points out that research and improvement should be accelerated on metrological indicators like particle concentration attenuation coefficient, volatile particle removal efficiency, and dilution ratio. Regarding the requirements for determining methyl chloroformate and benzo[a]pyrene pollutants specified in the Euro VI standard, China currently lacks corresponding reference materials and traceability systems. It is necessary to develop compliant reference materials and establish traceability standards to prepare for increasingly updated quality control requirements both domestically and internationally. The article also offers suggestions in response to the proposed European seventh stage emission standard (Euro 7).