Diffusive sampling for the validation of urban dispersion models

Although widely used in workplace, indoor and ambient air quality assessments, diffusive sampling has not yet been established as a common tool for dispersion model validation. In this study, three mathematical models (STREET, OSPM and AEOLIUS) that are likely to be used for regulatory purposes were validated against experimental data obtained in two street canyons in Paris. Diffusive tubes were used to sample a wide range of traffic-related organic compounds at different heights and distances from the kerb. Model input information (site geometry, meteorological and traffic data) was obtained from the competent authorities and compared with on site observations. An algorithm describing vertical pollutant dispersion and an empirical relationship between CO and benzene were used. Diffusive sampling might be seen as a practical and cost-effective method for creating data sets for dispersion model validation.