Pengfei Chen1, Shichang Kang 1,2, Chaoliu Li2,3, Quanlian Li1, Fangping Yan4, Junming Guo1, Zhenming Ji3, Qianggong Zhang2,3, Zhaofu Hu1, Lekhendra Tripathee1, Mika Sillanpää4,5

State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences (CAS), Lanzhou 730000, China
CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100085, China
Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, CAS, Beijing 100101, China
Laboratory of Green Chemistry, Lappeenranta University of Technology, 50130 Mikkeli, Finland
Department of Civil and Environmental Engineering, Florida International University, Miami, FL-33174, USA

Received: January 13, 2018
Revised: March 24, 2018
Accepted: March 25, 2018
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Cite this article:
Chen, P., Kang, S., Li, C., Li, Q., Yan, F., Guo, J., Ji, Z., Zhang, Q., Hu, Z., Tripathee, L. and Sillanpää, M. (2018). Source Apportionment and Risk Assessment of Atmospheric Polycyclic Aromatic Hydrocarbons in Lhasa, Tibet, China. Aerosol Air Qual. Res. 18: 1294-1304.


  • Atmospheric PAHs are more prevalent in Lhasa than in more remote sites in Tibet.
  • PMF model indicated that biomass and vehicle emissions are the main PAH sources.
  • Lifetime carcinogenic risk analysis revealed that PAHs pose no such risk to locals.


Much attention has been given to the distributions, sources, and health risks of atmospheric polycyclic aromatic hydrocarbons (PAHs) in cities. In this study, a total of 62 suspended particle samples were collected from April 2013 till March 2014 in the city of Lhasa. Positive matrix factorization (PMF) was applied to investigate the source apportionment of 15 priority PAHs, the lifetime carcinogenic risk (LCR) levels of which were assessed. The average annual particle phase PAH concentration was 43.9 ± 60.4 ng m–3. Evident seasonal variations of PAHs were observed, with the highest concentration observed in winter, followed by autumn, spring, and summer. Four- and five-ring PAHs accounted for the predominant proportion (63.3%–84.4%) throughout the year. Correspondingly, gas phase PAHs showed the opposite variations, with the highest and lowest concentrations observed in summer and winter, respectively; also, three-ring PAHs, especially Ace, Acel, and Flu, were the largest contributors. Compositions of particle phase PAHs varied seasonally, with four-ring PAHs contributing more in winter than in summer and five-ring PAHs exhibiting the opposite trend, thereby reflecting the variety of emission sources. PMF analysis showed that biomass combustion (48.4%) and vehicle emissions (27.9%) were the two main sources, followed by coal combustion and the air–surface exchange. These results were consistent with the diagnostic molecular ratios. The benzo(a)pyrene equivalent (BaPeq) concentration of particle phase PAHs ranged from 1.48 to 24.5 ng m–3, which exceeds were higher than the new limit in China (1 ng m–3). The average BaPeq of gas phase PAHs was 6.43 ± 4.15 ng m–3, which was similar to that of particle phase PAHs. The LCR of the total PAHs (9.08 × 10–6) was one time higher than that of the particle phase; however, it was slightly lower than the acceptable level, thereby indicating that atmospheric PAHs in Lhasa pose little or no carcinogenic risk to the local population.

Keywords: Polycyclic aromatic hydrocarbons; Source apportionment; Health risk; Tibetan Plateau.


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