Road vehicle non-exhaust particulate matter: Initial air quality model development and application, model uncertainty analysis and further model improvements

Traffic emissions of non-exhaust particulate matter contribute significantly to the concentrations of PM10 and PM2.5 in urban areas. However, these emissions are not well quantified compared to, for example, the corresponding emissions emitted from vehicle tailpipes. This work uses non-exhaust particulate emissions estimated from new emission factors in air dispersion modelling studies of a number of roadside locations. The model predictions are compared with measured concentration data. The factors used to calculate the non-exhaust emissions modelled have been taken from two sources. The tyre, brake and road wear emissions factors are those given in the EMEP methodology documentation, and the resuspension emissions factors are derived both in an earlier report from project CPEA23/SPU82, and in the current report. Seventeen sites have been selected at which concentration measurements of PM10 were recorded for significant periods between 2000 and 2002; ten of these sites additionally have measurements of PM2.5. The majority of the sites are located in Greater London and two sites are in Birmingham, close to the University. For the London sites, detailed emissions calculations have been performed using activity data given in the London Atmospheric Emissions Inventory; less accurate source data were available for Birmingham. The air dispersion model ADMS-Urban has been used to model the calculated emissions and predict annual average particulate concentrations. The comparison between modelled PM10 concentrations and monitored data is good, with the model estimating on average a 6% higher concentration of the measured value. The comparisons between modelled and measured concentrations are less good for PM2.5, with the average modelled concentration being 26% greater than the monitored value. However, the latter results are influenced by the significant uncertainty surrounding the conversion factor from the measured TEOM values to their gravimetric equivalent; some discussion regarding this subject is presented in the report. The report also presents some results of idealised scenarios. These include calculations of the relative proportions of the various traffic emissions components from simplified major and minor roads. In addition, initial investigations are presented of how the different source characteristics of the non-exhaust emissions (for example, height above road surface) may influence concentrations, which in turn affects the derivation of the resuspension emission factors; this effect needs further study. Finally, some discussion is presented of recommendations for further work involving detailed source apportionment of modelled and measured concentration data at the level of the different chemical constituents of the particulates. (A)

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  • English

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  • Accession Number: 01050862
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Files: ITRD
  • Created Date: Jun 5 2007 12:26AM