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Exposure to elevated concentrations of road traffic air pollutants mainly occurs within a few hundred metres of major roads, or while travelling in road vehicles.

Existing roadside air assessment tools are either crude and conservative, or are complex and demanding with no guarantee of improved accuracy. Neither approach is well suited to health risk assessment and both present substantial uncertainty for regulatory use.

A third approach was developed aimed at delivering moderate accuracy in a simple, accessible package, better suited to health risk applications. The roadside corridor model is a parameterised implementation of a more complex emission-dispersion model. It is implemented as a spreadsheet, suitable for integration into a GIS-based tool. Several practical applications of the model are demonstrated, including road project assessment, risk 'corridor' definition, and disaggregation of local and remote sources in roadside air quality monitoring data.

Much less is currently known about exposure inside vehicles. Ultrafine particles were measured in cars on Auckland roads. Concentrations varied over an order of magnitude between 'trips' and were larger than outdoors at non-trafficked locations. Concentrations within the vehicle cabin were reduced when the air was recirculated. Exposures were generally higher during periods of motorway driving.

Keywords: air quality, environment, modelling, particulate matter, pollution