Characterizing Operating Condition-Based Formaldehyde Emissions of Light-Duty Diesel Trucks in China Using a PEMS-HCHO System

Manni Zhu, Jiamin Ou, Songdi Liao, Fei Yu, Menghua Lu, Qinge Sha, Junwen Liu, Hancheng Zhong, Zeyan Wu, Zhuangmin Zhong, Junyu Zheng*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


Formaldehyde (HCHO) plays a critical role in atmospheric photochemistry and public health. While existing studies have suggested that vehicular exhaust is an important source of HCHO, the operating condition-based diesel truck HCHO emission measurements remain severely limited due to the limited temporal resolution and accuracy of measurement techniques. In this study, we characterized the second-by-second HCHO emissions from 29 light-duty diesel trucks (LDDTs) in China over dynamometer and real-world driving tests using a portable online HCHO emission measurement system (PEMS-HCHO), considering various operating conditions. Our results suggested that the HCHO emissions from LDDTs might be underestimated by the widely used offline DNPH-HPLC method. The HCHO emissions at a 200 s cold start from China V LDDT can be up to 50 mg/start. Different driving conditions over dynamometer and real-world driving tests led to a 2-4 times difference in the HCHO emission factors (EFs). Under real-world hot-running conditions, the HCHO EFs of China III, IV, V, and VI LDDTs were 43.5 ± 35.7, 10.6 ± 14.2, 8.8 ± 5.1, and 3.2 ± 1.2 mg/km, respectively, which significantly exceeded the latest California low emission vehicle III HCHO emission standard (2.5 mg/km). These findings highlighted the significant impact of vehicle operating conditions on HCHO emissions and the urgency of regulating HCHO emissions from LDDTs in China.

Original languageEnglish
Pages (from-to)1592-1599
Number of pages8
JournalEnvironmental Science and Technology
Issue number4
Publication statusPublished - 31 Jan 2023


  • dynamometer tests
  • formaldehyde
  • light-duty diesel trucks
  • online emission measurement
  • real-world driving emissions tests
  • vehicle operating conditions


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