EGU General Assembly 2020
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Analysis of urban air quality in 6 European cities by lower cost sensors, Lagrangian urban dispersion modelling and traffic flow modelling: the TRAFAIR project

Ohad Zivan1, Alessandro Bigi1, Giorgio Veratti1, José Antonio Souto González2, Lorena Marrodán3, Chiara Bachechi1, Sara Fabbi1, David Cartelle Fernández4, Xabier Diz Gerpe2, Grazia Ghermandi1, Giovanni Gualtieri5, Raquel Trillo Lado3, Javier Cacheiro López6, Ángel Rodríguez López4, Paolo Nesi7, Michela Paolucci7, Stefano Bilotta7, José Ramón Rı́os Viqueira8, Alessandro Zaldei5, and Laura Po1
Ohad Zivan et al.
  • 1Università degli studi di Modena e Reggio Emilia, Dipartimento di Ingegneria "Enzo Ferrari", Italy
  • 2Universidade de Santiago de Compostela, Department of Chemical Engineering, Santiago de Compostela, Spain
  • 3University of Zaragoza, Aragón Institute of Engineering Research (I3A), Zaragoza, Spain
  • 4Troposfera SC, Ferrol, Spain
  • 5Institute of Bio-Economy, National Research Council of Italy, Sesto Fiorentino, Italy
  • 6Galicia Supercomputing Centre (CESGA), Santiago de Compostela, Spain
  • 7University of Florence, Department of Information Engineering, DISIT Lab, Italy
  • 8Universidade de Santiago de Compostela, Centro Singular de Investigación en Tecnoloxı́as da Información (CiTIUS), Santiago de Compostela, Spain

Most of worldwide population lives in urban areas, demanding for air quality information with a high spatio-temporal resolution. The most promising approaches for estimating urban air quality within the complex urban topography are small sensor networks and simulation models.

The TRAFAIR project focuses on understanding the role of traffic emissions on urban air quality by the combination of dispersion modelling, space- and time-resolved gas monitoring by lower cost sensors and realistic traffic flow rates by dynamic traffic model based on real time traffic data. Test cities of TRAFAIR are Modena, Florence, Pisa, Livorno, Zaragoza and Santiago de Compostela.

Depending on the size of the urban area, from 6 to 13 sensors units are deployed across each city since August 2019, providing estimates of NO, NO2, CO and O3, along with RH and temperature. Metal oxide sensors are deployed in Tuscany (Florence, Pisa, Livorno) and electrochemical cells are used elsewhere. The units are calibrated on a regular basis by co-location at the air quality regulatory stations and subsequently deployed across the town to monitor several representative locations (e.g. Low Emission Zones, hospital surroundings). For each sensor the raw readings (e.g. mV for electrochemical cells) are collected and a regression model (e.g. Random Forest) is applied to derive a calibration function, exploiting the data from the regulatory stations during co-location periods; for instance in Modena, the first short-term calibration provided a model with a Mean Absolute Error between 5 – 6 ppb and 2 – 4 ppb for NO and NO2 respectively.

The sensors are used for both real-time urban air quality mapping and to test and validate the 24hr forecast service of NOx by the microscale lagrangian dispersion model GRAL. The simulation domains, covering the urban area of each TRAFAIR city, have a horizontal resolution of 4 m and allow to account for the presence of buildings. The dispersion model mainly focuses on NOx by traffic emissions, although domestic heating will be also included in the analysis. Vehicular emissions are based either upon historical traffic data (e.g. induction loops), or upon previously available traffic flow simulation, or upon traffic pattern reconstruction using a traffic flow model followed by a cluster analysis to group streets with similar pattern.

The final goal of the project is the development of a tool to support local policymakers and to inform citizenship about the quality of air and the impact of urban emission sources, particularly traffic. A secondary goal of the project is the development of a valuable QA/QC protocol for small sensor units and the optimization of the modelling chain for the forecast of traffic and domestic heating impact on local air quality at the urban scale.

How to cite: Zivan, O., Bigi, A., Veratti, G., Souto González, J. A., Marrodán, L., Bachechi, C., Fabbi, S., Cartelle Fernández, D., Diz Gerpe, X., Ghermandi, G., Gualtieri, G., Trillo Lado, R., Cacheiro López, J., Rodríguez López, Á., Nesi, P., Paolucci, M., Bilotta, S., Rı́os Viqueira, J. R., Zaldei, A., and Po, L.: Analysis of urban air quality in 6 European cities by lower cost sensors, Lagrangian urban dispersion modelling and traffic flow modelling: the TRAFAIR project , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13601,, 2020

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added a video for Santiago simulation
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