Significant reduction in atmospheric organic and elemental carbon in PM2.5 in 2+26 cities in northern China

Xu Dao, Dongsheng Ji, Xian Zhang, Jun He, Jiaqi Sun, Jianlin Hu, Yu Liu, Lili Wang, Xiaojuan Xu, Guigang Tang, Yuesi Wang

Research output: Journal PublicationArticlepeer-review

19 Citations (Scopus)


To better understand the change characteristics and reduction in organic carbon (OC) and elemental carbon (EC) in particulate matter (PM) with a diameter of ≤2.5 μm (PM2.5) driven by the most stringent clean air policies and pandemic-related lockdown measures in China, a comprehensive field campaign was performed to measure the carbonaceous components in PM2.5 on an hourly basis via harmonized analytical methods in the Beijing-Tianjin-Hebei and its surrounding region (including 2 + 26 cities) from January 1 to December 31, 2020. The results indicated that the annual average concentrations of OC and EC reached as low as 6.6 ± 5.7 and 1.8 ± 1.9 μg/m3, respectively, lower than those obtained in previous studies, which could be attributed to the effectiveness of the Clean Air Action Plan and the impact of the COVID-19-related lockdown measures implemented in China. Marked seasonal and diurnal variations in OC and EC were observed in the 2 + 26 cities. Significant correlations (p < 0.001) between OC and EC were found. The annual average secondary OC levels level ranged from 1.8–5.4 μg/m3, accounting for 37.7–73.0% of the OC concentration in the 2 + 26 cities estimated with the minimum R squared method. Based on Interagency Monitoring of Protected Visual Environments (IMPROVE) algorithms, the light extinction contribution of carbonaceous PM to the total amount reached 21.1% and 26.0% on average, suggesting that carbonaceous PM played a less important role in visibility impairment than did the other chemical components in PM2.5. This study is expected to provide an important real-time dataset and in-depth analysis of the significant reduction in OC and EC in PM2.5 driven by both the Clean Air Action Plan and COVID-19-related lockdown policies over the past few years, which could represent an insightful comparative case study for other developing countries/regions facing similar carbonaceous PM pollution.

Original languageEnglish
Article number113055
JournalEnvironmental Research
Publication statusPublished - Aug 2022


  • Beijing-Tianjin-Hebei and its surrounding region of China
  • Elemental carbon
  • Light extinction
  • Organic carbon
  • PM
  • Temporal variation

ASJC Scopus subject areas

  • Biochemistry
  • General Environmental Science


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