Newer Generation of Scooters: Polychlorinated Dibenzo-p-dioxin and Dibenzofuran and Polychlorinated Biphenyl Reductions

Scooter emissions have attracted attention in recent years because of human exposure to their direct effects in urban areas. Trace toxics, such as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) have thus become important in scooter emissions. In th...

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Bibliographic Details
Published in:Aerosol and Air Quality Research 2020-06, Vol.20 (6), p.1495-1509
Main Authors: Chen, Jheng-Hong, Shen, Yun-Hwei, Yang, Hsi-Hsien, Lu, Jau-Huai, Wang, Lin-Chi, Hsieh, Yen-Kung, Lee, Chia-Fon, Lin, Sheng-Lun
Format: Article
Language:English
Subjects:
Automotive parts
Carburetors
Catalytic converters
Cities
Congeners
Dibenzo-p-dioxin
Dibenzofuran
Dioxins
Emission control equipment
Emission standards
Emissions
Emissions control
Exhaust pipes
Exhaust systems
Feedback control
Fuel injection
Health risk assessment
Health risks
Industrial plant emissions
Mobility scooters
Onboard equipment
PCB
Pollutants
Polychlorinated biphenyls
Polychlorinated dibenzodioxins
Polychlorinated dibenzofurans
Population
Scooters
Urban areas
VOCs
Volatile organic compounds
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Summary:Scooter emissions have attracted attention in recent years because of human exposure to their direct effects in urban areas. Trace toxics, such as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) have thus become important in scooter emissions. In this work, ten Tier 5 and 6 scooters were tested using a 100-second model to analyze their PCDD/F and PCB emissions and compare the results with previous Tier 3 studies. Tier 5 and 6 scooters emitted 1.86-2.91 and 0.133-0.298 pg WHO-TEQ Nm^(-3) of PCDD/Fs and PCBs, respectively. It was interesting to find that the PCDD/Fs were reduced by 94.6-97.4% and 99.4-99.6% in Tier 5 and 6 motors, respectively. The congener profiles of PCDD/Fs were affected by improving the emission control. The domination of highly chlorinated congeners shown in Tier 3 was reduced in Tier 5 with increases in low chlorinated PCDFs. This showed that de novo synthesis occurred and could be inhibited by the OBD system in Tier 6. The tailpipe renews reduced 60.0-93.8% of PCDD/Fs and 85.3-97.7% of PCB emissions, but several cases would still exhibit a delay for stable operation of a catalytic converter. The annual emissions of PCDD/F TEQ was calculated based on the statistics in 2019 and tested as 1.63 g WHO-TEQ. It could be 99.7% reduced to 3.55 mg by replacing all scooters with Tier 6. Consequently, the improvement of electronic fuel injection and on-board diagnostics systems from a carburetor without feedback control not only reduced the regulated pollutants but effectively reduced PCDD/F emissions.
ISSN:1680-8584
2071-1409
DOI:10.4209/aaqr.2020.04.0138