Lulu Duan1, Yu-Lun Hsieh2, Sheng-Lun Lin   2, Wan Nurdiyana Wan Mansor3,4, Muhammad Isyhraff Azhan Bin Mansor3, Hyojun Lee5, Chien-Er Huang6,7, How-Ran Chao8, Mengjie Song1, Minseop Song5 

1 School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081, China
2 Department of Environmental Engineering, National Cheng Kung University, Tainan 70101, Taiwan
3 Faculty of Ocean Engineering Technology, Universiti Malaysia Terengganu, 21300, Kuala Nerus, Malaysia
4 Syngas Research Group, Universiti Malaysia Terengganu, 21300, Kuala Nerus, Malaysia
5 Department of Nuclear Engineering, Hanyang University, Seoul 04763, Korea
6 Center for Environmental Toxin and Emerging-contaminant Research, Cheng Shiu University, Kaohsiung 83347, Taiwan
7 Department of Mechanical Engineering, Cheng Shiu University, Kaohsiung 83347, Taiwan
8 Department of Environmental Science and Engineering, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan

Received: March 18, 2024
Revised: June 28, 2024
Accepted: June 30, 2024

 Copyright The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.

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Cite this article:

Duan, L., Hsieh, Y.L., Lin, S.L., Wan Mansor, W.N., Mansor, M.I.A.B., Lee, H., Huang, C.E., Chao, H.R., Song, M., Song, M. (2024). Unignorable Emissions and Potential Health Effects of Unregulated Pollutants from Nonroad Engines Using Greener Fuels — A Review. Aerosol Air Qual. Res.


  • Stringent emission regulations are imposed on non-road machineries worldwidely.
  • Unregulated emissions of non-road machineries cuase potential health effects.
  • Unregulated pollutants in eingines include PN, EC/OC, PAHs, VOC, POPs, and metals.
  • Greener fuels lower traditional emissions but unregulated pollutants in engine.


Nonroad mobile machinery such as construction equipment, agricultural machinery, ships, and generators emit significant pollutants. Countries worldwide have implemented stringent emission regulations targeting pollutants like CO, HC, NOx, and PM. However, these machines also emit unregulated pollutants such as PAHs, VOCs, POPs, and metals, which severely impact human health and the atmosphere. A key strategy to reduce these emissions is using green fuels, including biodiesel, oxygenated fuels, metal additives, hydrogen, and ammonia. This paper analyzes the impact of these fuels on non-road machinery emissions of unregulated pollutants. Results indicate that green fuels can reduce some harmful emissions but may increase others. Biodiesel and oxygenated fuels significantly reduce PAHs and soot emissions, but their effect on VOCs varies with fuel type and engine load. Metal additive fuels effectively reduce EC/OC, smoke, and particle number emissions but may increase total PAHs and BaPeq emissions. Currently, research on using metal additive fuels, hydrogen, and ammonia in generators is limited, focusing mainly on biodiesel and oxygenated fuels. Similarly, studies on unregulated emissions from ships using clean fuels are scarce. Most research concentrates on PAHs, PN, and EC/OC emissions, with less focus on POPs, N2O, VOCs, and metal components.

Keywords: Nonroad engine, Oxygenated fuels, Metal additive fuels, Greener fuel, Unregulated pollutants

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