Experimental Quantification and Modelling of Dispersion of Particles in Urban Street Canyons

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Ultrafine particles associated with vehicle use can be particularly harmful to health because of their ability to penetrate the cell walls of the lung. While a reasonable amount of data are available on vehicle emissions there is little information on particle emissions from tyre wear and brake linings and the re-suspension of dust from roads by traffic. This project will:

  • Obtain information on rates of emission of particles from road surfaces into the atmosphere
  • Use the data obtained, together with other ongoing wind tunnel work, to predict particulate concentration at the end of vehicle near wakes.
  • Develop a large eddy simulation model of street canyon geometries to predict the unsteady wind fields, particulate concentrations within the canyon and fluxes from the canyon.


Birmingham, West Midlands


Wind Tunnel Experiments to measure particle emissions from roads by direct wind action

Measurements will be made in the University of Birmingham large wind tunnel, currently at Porton Down. Real road dust samples will be deposited on typical road surfaces within the tunnel and particle emissions measured for a range of wind-induced shear stresses.

Wind tunnel experiments to measure dispersion of particles from vehicles

The Motor Industries Research Association facilities are being used to measure particle dispersion from vehicle exhaust pipes and the road/wheel interface to the end of the near wake. The studies are being carried out by a MIRA-supported student at the University of Nottingham. Experimental studies are being carried out to measure exhaust gas concentrations at various positions in the wake. Computational Fluid Dynamic studies of the problem are also underway.

Development of a street canyon local scale large eddy simulation model

The Colorado State University RAMS model will be used to predict velocity fields within urban street canyons, and also to derive concentrations and size distributions of particles within the street canyon together with the particulate flux from the top of the canyon. Air quality data collected in the West Midlands July1999 and January 2000, will be used for model verification.

Start date/duration

April 2000 Three years

Lead Organisation

University of Birmingham


  • Data and results will be disseminated URGENT and the wider scientific, industrial and local authority communities.
  • Emission rates of particles from street canyons will be widely publicised and provided for relevant environmental scientists, managers and health workers.

The information obtained will help planners and decision makers in the future design of urban areas and control of traffic.


Environmental scientists, managers and health workers in urban applications

Further details

Further information is available from the following contacts:

Lead Researcher: Professor C Baker

Tel: 0121 414 5049, Fax: 0121 414 3675, e-mail: c.j.baker@bham.ac.uk 

URGENT Programme Manager: Graham Leeks

Tel: 01491 692203, Fax: 01491 692313, e-mail: gjll@ceh.ac.uk