Effectiveness of replacing catalytic converters in LPG-fueled vehicles in Hong Kong

X. P. Lyu, H. Guo, I. J. Simpson, S. Meinardi, P. K.K. Louie, Z. H. Ling, Y. Wang, M. Liu, C. W.Y. Luk, N. Wang, D. R. Blake

Research output: Journal article publicationJournal articleAcademic researchpeer-review

1 Citation (Scopus)


Many taxis and public buses are powered by liquefied petroleum gas (LPG) in Hong Kong. With more vehicles using LPG, they have become the major contributor to ambient volatile organic reduce the emissions of VOCs and nitrogen oxides (NOx) from LPG-fueled vehicles was implemented by the Hong Kong Government in September 2013. Long-term real-time measurements indicated that the program was remarkably effective in reducing LPG-related VOCs, NOx and nitric oxide (NO) in the atmosphere. Receptor modeling results further revealed that propane, propene, i-butane, n-butane and NO in LPG-fueled vehicle exhaust emissions decreased by 37.3 ± 0.4, 50.2 ± 0.3, 32.9 ± 0.4, 41.1 ± 0.4 and 75.9 ± 0.3 %, respectively, during the implementation of the program. In contrast, despite the reduction of VOCs and NOx, the O3 production following the program increased by 0.25 ± 0.04 ppbv h-1 (4.8 %). Moreover, the production rate of HOx decreased due to the reduction of VOCs, whereas NO reduction resulted in a more significant decrease of the HOx in destruction compared to the decrease in production, and an increase of hydroxyl (OH) and hydroperoxyl (HO2). Analysis of O3-VOCs-NOx sensitivity in ambient air indicated VOC-limited regimes in the O3 formation before and during the program. Moreover, a maximum reduction percentage of NOx (i.e., 29.4 %) and the lowest reduction ratio of VOCs / NOx (i.e., ∼ 3 : 1) in LPG-fueled vehicle emissions were determined to give a zero O3 increment. The findings are of great help to future formulation and implementation of control strategies on vehicle emissions in Hong Kong.

Original languageEnglish
Pages (from-to)35939-35990
Number of pages52
JournalAtmospheric Chemistry and Physics Discussions
Issue number24
Publication statusPublished - 21 Dec 2015

ASJC Scopus subject areas

  • Atmospheric Science
  • Space and Planetary Science


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