Urban dispersion models provide a way of calculating how pollutants travel through street and junction networks, building canyons, and across the wider urban area. They help complete missing measurement records, explore scenarios, and underpin decisions regarding monitoring network design, planning…
Urban air pollution policy commonly utilises averages. Daily means, annual objectives, and longer-term monitoring data are all important indicators of general air quality and can be used to compare trends, evaluate standards and measure broad policy changes. Averages are, however,…
Policy on air pollution in the urban environment relies on evidence. That evidence does not come from one monitor, one model or one field campaign. It is constructed over time from measurements, experiments, models, comparisons and interpretations. That is particularly…
Often, model validation is considered just one of many technical elements of the modelling exercise. A model is developed, validated against measurements, and revised as appropriate before being used to fill in conditions where measurements are not available. In the…
Street-based studies provide the essential evidence required for urban air pollution research. Yet, in a real-world environment, performing controlled experiments is almost impossible. Traffic patterns fluctuate, wind directions shift, background pollution levels change, and that exact set of circumstances never…
Urban dispersion research has never been the business of a single viewpoint. To truly comprehend how air and pollution travel through the streets of a city, relying on observation alone or numerical models alone is insufficient. It takes a combination…
Monitoring of urban pollution has been largely dependent upon relatively small numbers of stationary monitoring locations. Although there is certainly value in being able to provide high-quality data for a continuous period from a fixed monitoring station, these do not…
Urban airborne releases are difficult to model as the city itself is not a flat land surface. Urban structure, including streets, intersections, traffic and local meteorology, will play a major part in determining how material released to the atmosphere will…
Urban dispersion research has to deal with a fundamental dilemma. On the one hand, it needs to draw on field evidence, which is obtained in the real world in which all components of the urban system – buildings, people, traffic,…
City pollution stories mostly focus on emissions: traffic, vehicles, fuel, industrial sources and background pollution. These are relevant, but they do not tell the whole story, because once emissions enter the city, they are subject to transport, recirculation, dilution and…