UrbanAIR develops a database to advance towards a digital twin of air quality in Barcelona
- Barcelona Supercomputing Center Team
- Apr 2
- 4 min read
Updated: 6 days ago
This article features the work of early-career researchers Álvaro Criado and Cristina Carnerero at the BSC-CNS, contributing to the European UrbanAIR project.
For the first time, six years of daily NO₂ pollution data for the entire Barcelona area are being published openly, with annual maps of every street in the city and information on the reliability of the estimates.
● The new database includes maps showing the probability of exceeding NO₂ limits, as established by both European regulations and WHO airquality guidelines.
● The work is part of the European UrbanAIR project, with Barcelona, Antwerp and Paris as case studies.
Having reliable, detailed, and accessible data on air quality is essential for assessing population exposure and designing effective public policies to advance towards healthier urban environments. In this context, researchers from the Earth Sciences Department at the Barcelona Supercomputing Centre – Centro Nacional de Supercomputación (BSC-CNS) have developed an open database with detailed maps of nitrogen dioxide (NO₂) pollution in Barcelona, which also show where estimates are more or less reliable.
This work, published in Nature's Scientific Data journal, is based on the CALIOPE-Urban air quality prediction system, developed at BSC, and lays the foundations for the development of urban digital twins within the framework of the European UrbanAIR project, with Barcelona as a case study.
“The availability of urban air quality data allows us to assess the actual exposure of the population; by indicating the degree of reliability of the data, we can design more robust policies that take into account the limitations of the information” ,
explains Jan Mateu Armengol, leader of the air quality services team of the Earth System Services (ESS) group at BSC.
The open-access database contains six years of air quality data (2019–2024) and, for the first time, provides daily concentrations for all census sections in Barcelona, as well as annual NO₂ maps at the level of each street in the city. Having daily, high-resolution data, which was not previously available in open databases for Barcelona, makes it possible to identify the most polluted areas more accurately and support decisions aimed at protecting public health. The number of official air quality stations is limited and does not always represent the situation in different streets and neighbourhoods, so these maps are necessary to understand exposure at the local level.
In addition, it shows how reliable the estimates are and incorporates maps of the probability of exceeding the limits set by both European regulations and WHO air quality guidelines, which is essential for assessing health risks, detecting territorial inequalities, and supporting environmental and urban policies.
“For the first time, we have a continuous daily series of six years of NO2 data for the entire city, with explicit information on the uncertainty of each estimate and the probability of exceeding the established thresholds” ,
says Álvaro Criado, lead author of the study and air quality researcher at the ESS group. He adds:
“Our high-resolution data allows us to identify critical areas for intervention, where it is a priority to pay special attention to groups that are vulnerable to air pollution.”
The data is generated from CALIOPE-Urban, a system developed by the BSC's Earth Sciences Department that combines models simulating air quality at both regional and urban scales to estimate air pollution with very high resolutions at any point in the city. The results are integrated with observations from official air quality stations and, using an artificial intelligence model, are combined with low-cost sensor campaigns, building density information, meteorological variables, and a wide range of other geospatial information.
The database is also available through uncertAIR, an open platform for visualising and downloading air quality data developed as part of a local project funded by Barcelona City Council. Both the project and the platform were designed through a co-creation process involving users involved in air quality management, research, and communication, with the participation of public administrations, civil society organisations, and private companies.
“The dataset developed in this study is a key element of Barcelona's use case in UrbanAIR, as it allows us to work with detailed urban information and an explicit characterisation of its uncertainty,”
says Cristina Carnerero, a researcher in the ESS group and the BSC's main participant in UrbanAIR.
About the UrbanAIR project
The research provides the scientific basis for the Barcelona case study within the European UrbanAIR project, by making available a set of urban-scale air quality data that integrates NO2 concentrations with an explicit characterisation of their uncertainty. These data enable progress towards the concept of an urban digital twin applied to air pollution. The BSC's Earth Sciences Department plays a central role in the project, which involves leading institutions such as Imperial College London, Delft University of Technology and Vito.
UrbanAIR is part of the major European initiative Destination Earth, which aims to develop a digital twin of the Earth to monitor changes in the Earth system and support climate change adaptation and mitigation strategies. Within this framework, UrbanAIR transfers the concept of digital twins to the urban environment, with the aim of creating a platform to support decision-making in urban planning, particularly in areas such as air quality and heat stress. Complementing this, the European project TerraDT, considered a ‘sister’ initiative to UrbanAIR, addresses the incorporation of cryosphere components, aerosols, land surface, carbon storage, and climate extremes into Destination Earth's digital twin for climate adaptation.
Barcelona is, along with Antwerp and Paris, one of the three pilot cities in the project that will serve as case studies focusing on air pollution. A distinguishing feature of UrbanAIR is its co-design approach with local governments and urban stakeholders, ensuring that the tools developed enable risk assessment, climate adaptation planning, and progress towards healthier, safer, and more resilient urban environments.
About the #UAYoungResearchers Campaign
This feature is part of our #UAYoungResearchers campaign. We are shining a spotlight on the PhD students, postdocs, and early-career scientists like Álvaro and Cristina who are the driving force behind the UrbanAIR project.
Our young researchers are not just analyzing data; they are building the digital tools that city planners will use to create healthier, safer, and more resilient urban environments.
Follow the journey: Check out the #UAYoungResearchers hashtag on social media to see "behind-the-scenes" lab work, field campaigns from our pilot cities, and more interviews with the next generation of climate and air quality experts.
Reference:
Criado, A., Carnerero, C., Frangeskou, A. et al. Street- and census-level NO2 data for
Barcelona with uncertainty and exceedance probability mapping. Sci Data (2026).
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