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Implementation of an operational near real time model for exposure analysis and risk assessment


The ability to deliver high resolution NO2 exposure calculations on a regional (Belgian) scale is highly innovative. Results and procedures to calculate population exposure of NO2 at high spatial resolution on a regional scale is new within the EU air quality modelling community and can be used for assessment of European air quality standards. Moreover, the publication of NO2 exposuremaps on an hourly basis on a public website is a new and pioneer practice within the EU context.

After the validation and improvement of the RIO-IFDM model chain in WP5, the model was installed on servers at IRCEL to run in operational mode to produce hourly NO2 concentration maps, from which NO2 exposure can be calculated. The setup of this new operational chain implied the preparation of the most recent available emission data as well as the connection to an operational meteorological model, both serving as input for the IFDM part of the model chain.

In order to install a high resolution model chain in near-realtime it was essential to reduce the calculation time (including post-processing) to less than 1 hour. To achieve this, the model code of IFDM was parallelized and optimized in cooperation with the University of Hasselt and VITO-RMA for the calculation of line and point sources. Additionally, the model performance was increased further by optimizing the model grid, which was done in a way as to reach a sufficiently dense receptor grid at locations where large concentration gradients are expected and a lower point density at background locations with little or small emission sources present. As such, the overall number of grid points could be reduced to a minimum without sacrificing model performance, leading to a large reduction in time needed to carry out the model calculations.

As a result of these optimizations the required calculation time has significantly decreased, making it possible to produce the final deliverable of this project: NO2 concentration maps on an hourly basis in near-real time, combined with a population exposure estimate .