Project context

Road transport is often the main source of air pollution in urban areas worldwide. There are several methods and approaches that are useful for different scales of analysis. Usually, regional traffic emission models based on average speed or on traffic situations are commonly used at the city scale for the compilation of urban inventories. Still, this level of detail is not enough to understand the high pollutant concentrations that occur in specific urban environments or hot-spots.

In urban environments, meteorological effects and dispersion processes have a huge influence on the accurate description of the spatio-temporal distribution of pollution that shows strong concentration gradients along the day and in short distances. These concentration gradients can be depicted with very detailed air quality models. Those models are highly dependent on the emission description (mostly those of traffic) that must be accurately captured. In these urban environments, more detailed traffic emission models are needed to consider the individual behavior of vehicles in the network. Currently, highly detailed emission models, that can be used for microscale studies, have been analyzed. But, there is a lack of techniques or methodologies available to understand the influence of urban traffic emissions under an integrated multi-scale approach.

An integrated approach would help to accurately understand the potential impact that these very local, high concentrations may have on the real exposure of the population and, therefore, the relevance of the reduction measures that may be adopted, helping to safeguard citizens’ health. Important efforts have been invested in integrating detailed information from traffic models into emissions models and coupling them to highly detailed air quality models to provide solutions for specific highly polluted urban areas. However, it is crucial to know the effects at the city scale to undertake suitable policy actions and legal mechanisms.

To understand the real implication and to analyze the potential of local abatement measures there is a clear need to estimate the contribution of road traffic to atmospheric emissions at the city level and in great detail by using a hybrid calculation approach (macroscale information with enough detail for microscale analysis). This is an essential resource for local and central governments that are exploring different strategies to tackle the impacts of air pollution in urban areas.

The aim of the IRTEMS project is to contribute to drastically improve our knowledge in this key field.