A large reduction in airborne particle number concentrations at the time of the introduction of "sulphur free" diesel and the London Low Emission Zone

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  • Department of Environmental Sciences / Center of Excellence in Environmental Studies, King Abdulaziz University, PO Box 80203, Jeddah, 21589, Saudi Arabia


Hourly measurements of airborne particle number concentration (a metric dominated by ultrafine particles) at two sites in London and a site in Birmingham show that over a period of a few months in late 2007 concentrations were reduced by between 30 and 59%. At the London kerbside site particle number emissions from vehicles were reduced by 65% compared to emissions of NOx. These reductions occurred at the same time as the introduction of "sulphur free" diesel fuel and the London Low Emission Zone for heavy goods vehicles, and in view of the reduction in Birmingham and the limited change in vehicle technologies at that time, is probably primarily due to the change in fuel sulphur. There is an absence of any similar reduction in the concentration of the regulated air quality mass metrics which may provide an opportunity for further evaluating the effects of ultrafine particle concentrations on human health. (C) 2012 Elsevier Ltd. All rights reserved.


Original languageEnglish
Pages (from-to)129-138
Number of pages10
JournalAtmospheric Environment
Early online date5 Jan 2012
Publication statusPublished - 1 Apr 2012


  • Low Emission Zone, Particulate matter, Particle number count, Sulphur free fuel