Peak season ozone levels in European cities — sector contributions and cost of premature deaths

Figure 1. Peak season ozone levels in European cities — sector contributions and cost of premature deaths

The figures are taken from the Copernicus Atmosphere Monitoring Service (CAMS) Policy Support Service and are calculated using the Air Control Toolbox (ACT), developed by Ineris. ACT is an interactive visualisation platform that helps assess how custom emissions scenarios affect ozone levels. The scenarios show levels of primary pollutants and precursors before and after uniform and long-term Europe-wide reductions. ACT is based on a surrogate model of the full CHIMERE Chemistry-Transport Model (Colette et al., 2022).

City‑level diagnostics are also available and include information on ozone pollution sources. In addition, for each city, the estimated number of premature deaths attributable to exposure to ozone levels above the peak season value of 60 µg/m³ is provided as total years of life lost. This is based on the EEA’s burden of disease calculations. Furthermore, the economic cost of years of life lost is estimated using the monetary value of a life-year (VOLY), which was set at EUR 111,470 for 2021.

Material and method

The dashboard shows how much different sectors contribute to the yearly peak season ozone levels in cities.  Since ozone is a secondary pollutant, it is not emitted directly but forms when heat and light cause chemical reactions between various precursors such as nitrogen oxides (NOx) and volatile organic compounds (VOCs).

Anthropogenic sectors emitting ozone precursors and the hemispheric transport of ozone (from natural or anthropogenic origin without distinction) are among the contributions included in the dashboard. Again, the calculations use the Air Control Toolbox. For 2024, Ineris data include:

• European cities as defined by Eurostat Urban Audit
• six targeted activity sectors — industry, residential, traffic, shipping, agriculture and others (including solvents, aviation, offroad, waste and the GNFR sector others)
• the natural and hemispheric contribution.

Note that ‘shipping’ and ‘the natural and hemispheric contribution’ were not treated as separate sectors before 2024. Until 2023, ‘others’ included shipping, solvents, aviation, offroad, waste, the GNFR sector ’others’ as well as natural and hemispheric contributions, which led to a misleading representation of the anthropogenic contribution to ozone levels. Therefore, only 2024 data are considered for the analysis.

Contributions from all these sectors are presented with Air Quality Health Risk Assessments (HRAs) for core cities for 2023 (the latest year with available data), which were produced by the EEA. When the corresponding 2024 HRA results become available, they will be incorporated to ensure consistency with the 2024 sectoral contributions.

The analysis makes two main assumptions:

1. The relative contributions to ozone concentrations from sectoral activities are assumed to be the same as the relative contributions to mortality estimates (i.e. the toxicity profiles of the different sector emissions are assumed to be similar).
2. In their methodology, Ineris estimates sectoral contributions at the grid-point level over the CAMS modelling domain. These contributions are then extracted for each city by intersecting grid points with city polygons. The contributions estimated by ACT are assumed to be representative of the entire city.

The years of life lost within each city are converted to a cost using VOLY for 2021. VOLY is applied to the number of years of life lost (YLL), which takes into account the age at which people died. The YLL and associated cost thus increase as the share of younger people dying from the impacts of air quality increases. In any case, the VOLY value applied is EUR 111,470, as used in other EEA externality calculations.