Indicator Specification

Air pollution due to ozone: health impacts and effects of climate change

Indicator Specification
  Indicator codes: CLIM 006
Published 21 Dec 2015 Last modified 23 Feb 2021
11 min read
The indicator presents an overview of ozone concentrations over Europe in recent years, their effects on human health, and an estimate of the changes in these concentrations due to the effect of climate change. It presents the following: The annual mean of the maximum daily eight hour mean ozone concentrations by station type. The modelled projected change, due to climate change, in summertime surface ozone concentrations over Europe in the middle and at the end of the 21 st century. The relative effect of climate change on ozone concentrations in the middle of the 21 st century, compared to other contributions. A selection of meteorological parameters that might increase under future climate change and their impact on ozone levels.

Assessment versions

Published (reviewed and quality assured)
  • No published assessments


Justification for indicator selection

Tropospheric or ground-level ozone is primarily an air pollutant, which is of high concern in Europe due to its effects on human health, vegetation and materials. But ozone is also a short-lived climate pollutant, since it is a greenhouse gas and contributes to the warming of the troposphere (EEA, 2014).

Concentrations of ground-level ozone are determined by both precursor emissions and meteorological conditions, which also influence the transport of ozone and its precursors between continents (UNECE, 2010). Climate change could affect future ozone concentrations due to its impact on the availability of ozone precursors and on the dynamic and photo-chemical processes that control ozone production, dispersion and deposition.

Scientific references

  • ECDC, 2005, Eurosurveillance, Vol.10, Issues 7–9, European Centre for Disease Prevention and Control, Stockholm.
  • EEA, 2014, Air quality in Europe – 2014 report. EEA Report 5/2014, European Environment Agency, Copenhagen, 2014.
  • EPI, 2006, 'Setting the Record Straight: More than 52,000 Europeans Died from Heat in Summer 2003', Plan B Updates, 28 July 2006, Earth Policy Institute.
  • EU, 2013, Commission Staff Working Document Impact Assessment, SWD (2013)531.
  • WHO, 2013, Review of evidence on health aspects of air pollution - REVIHAAP Project, Technical Report. World Health Organization, Regional Office for Europe, Copenhagen, Denmark.
  • WHO, 2008, Health Risks of Ozone from Long-range Transboundary Air Pollution. eBook ISBN: 9289042907. Print ISBN: 9289042893. 
  • UNECE, 2010, Hemispheric Transport of Air Pollution 2010. Part A. Ozone and Particulate Matter. Air Pollution Studies No. 17, United Nations, Geneva.
  • EEA, 2010a, Air Pollution by Ozone across Europe during summer 2009, EEA Technical report 2/2010
  • EEA, 2010b, The European Environment – State and Outlook 2010: Air Pollution — SOER 2010 Thematic Assessment
  • EEA, 2012, Air Pollution by Ozone across Europe during summer 2011, EEA Technical report 1/2012
  • Jacob, Daniel J. and Darrell A. Winner, 2009: “Effect of Climate Change on Air Quality,” Atmospheric Environment 43, no. 1 (January 2009): 51–63, doi:10.1016/j.atmosenv.2008.09.051
  • Riahi, K., F. Dentener, D. Gielen, A. Grubler, J. Jewell, Z. Klimont, V. Krey, D. McCollum, S. Pachauri, S. Rao, B. van Ruijven, D.P. van Vuuren and C. Wilson, Energy Pathways for Sustainable Development. In: N. Nakicenovic, Editor, Global Energy Assessment: Toward a Sustainable Future, IIASA, Laxenburg, Austria and Cambridge University Press, Cambridge, United Kingdom and New York, NY (2012).
  • Royal Society, 2008, Ground-level ozone in the 21st century: future trends, impacts and policy implications. Fowler, D. (Chair) Science Policy Report, London, 2008.
  • EEA, 2015, Air quality in Europe – 2015 report. EEA Report 5/2015, European Environment Agency, Copenhagen, 2015.

Indicator definition

The indicator presents an overview of ozone concentrations over Europe in recent years, their effects on human health, and an estimate of the changes in these concentrations due to the effect of climate change. It presents the following:

  • The annual mean of the maximum daily eight hour mean ozone concentrations by station type.
  • The modelled projected change, due to climate change, in summertime surface ozone concentrations over Europe in the middle and at the end of the 21st century.
  • The relative effect of climate change on ozone concentrations in the middle of the 21st century, compared to other contributions.
  • A selection of meteorological parameters that might increase under future climate change and their impact on ozone levels.


The units used in this indicator are as follows:

  • Ozone concentrations: micrograms of ozone per cubic meter (µg/m³) or parts per billion (ppb), where 1 ppb 2 µg/m³.
  • Change in ozone concentrations: absolute (µg/m³) and relative (%) difference in surface summertime ozone concentrations in a given period (2041-2070 or 2071-2100) compared to the reference period (1960-2010).
  • SOMO35: Sum of Ozone Maxima Over 35 ppb. This is the yearly sum of the maximum daily 8-hour running average over 35 ppb (70 µg/m³).

Policy context and targets

Context description

High-levels of ozone cause breathing problems, trigger asthma, reduce lung function and cause lung disease (WHO, 2008). Epidemiological health evidence of chronic effects from exposure to ozone is now emerging, indicating considerably larger mortality effects than from acute exposure alone (WHO, 2013). The estimated effects of excessive exposure to ozone in 2010 for the EU-28 include about 26 500 premature deaths, 19 000 respiratory hospital admissions and 86 000 cardiovascular hospital admissions (people older than 64), and up to almost 109 million person-days with minor activity restrictions (all ages) (EU, 2013). The effect of ozone concentrations on total mortality, based on 2012 values, led to about 17 000 premature deaths in 40 European countries and about 16 000 in the EU-28 (EEA, 2015). There is scarce evidence that high ozone levels can further increase mortality during heat waves (ECDC, 2005; EPI, 2006).

In the Communication “A Clean Air Programme for Europe”, the EU Clean Air Policy Package, adopted by the European Commission on 18 December 2013, proposes the short-term objective of achieving full compliance with existing legislation (Air Quality Directive 2008/50/EC) by 2020 at the latest; and the long-term objective of no exceedences of the WHO guideline levels for human health.

Some of the priority objectives of the Seventh EU Environment Action Programme are to protect, conserve and enhance the EU's natural capital; safeguard its citizens from environment-related pressures and risks to health and well-being; and enhance the sustainability of its cities.

The European Commission and the European Environment Agency have developed the European Climate Adaptation Platform (Climate-ADAPT) to share knowledge on observed and projected climate change and its impacts on environmental and social systems and human health, relevant research, EU, national and sub-national adaptation strategies and plans, and adaptation case studies.

In April 2013, the European Commission presented the EU Adaptation Strategy Package. This package consists of the EU Strategy on adaptation to climate change and a number of supporting documents. One of the objectives of the EU Adaptation Strategy is “Better informed decision-making”, which should occur through bridging the knowledge gap and further developing Climate-ADAPT as the ‘one-stop shop’ for adaptation information in Europe. Further objectives include “Promoting action by Member States” and “Climate-proofing EU action: promoting adaptation in key vulnerable sectors”. Many EU Member States have already taken action, such as by adopting national adaptation strategies, and several have also prepared action plans on climate change adaptation.


The following policy targets have been set:

Directive 2008/50/EC:
• A long-term objective for ozone levels of 120 microgram per cubic metre (µg/m3) as a maximum daily 8-hour mean within a calendar year (not to be exceeded any day). No attainment date specified.
• A target value for ozone, equal to the long-term objective, not to be exceeded more than 25 days per calendar year, averaged over three years. It had to be met in 2010 (average 2010 to 2012).

WHO Air Quality Guidelines:
• Daily maximum 8-hour mean of ozone concentrations: 100 µg/m3.

Clean Air Programme for Europe:
• Reduce ozone-acute-premature deaths in 2025 by between 28 and 39 % in relation 2005 figures.

Related policy documents

  • 7th Environment Action Programme
    DECISION No 1386/2013/EU OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 20 November 2013 on a General Union Environment Action Programme to 2020 ‘Living well, within the limits of our planet’. In November 2013, the European Parliament and the European Council adopted the 7 th EU Environment Action Programme to 2020 ‘Living well, within the limits of our planet’. This programme is intended to help guide EU action on the environment and climate change up to and beyond 2020 based on the following vision: ‘In 2050, we live well, within the planet’s ecological limits. Our prosperity and healthy environment stem from an innovative, circular economy where nothing is wasted and where natural resources are managed sustainably, and biodiversity is protected, valued and restored in ways that enhance our society’s resilience. Our low-carbon growth has long been decoupled from resource use, setting the pace for a safe and sustainable global society.’
  • A Clean Air Programme for Europe
    Communication from the Commission to the Council, the European Parliament, the European Economic and Social Committee and the Committee of the Regions - "A Clean Air Programme for Europe", COM(2013) 918 final
  • Climate-ADAPT: Adaptation in EU policy sectors
    Overview of EU sector policies in which mainstreaming of adaptation to climate change is ongoing or explored
  • Climate-ADAPT: Country profiles
    Overview of activities of EEA member countries in preparing, developing and implementing adaptation strategies
  • DG CLIMA: Adaptation to climate change
    Adaptation means anticipating the adverse effects of climate change and taking appropriate action to prevent or minimise the damage they can cause, or taking advantage of opportunities that may arise. It has been shown that well planned, early adaptation action saves money and lives in the future. This web portal provides information on all adaptation activities of the European Commission.
  • Directive 2008/50/EC, air quality
    Directive 2008/50/EC of the European Parliament and of the Council of 21 May 2008 on ambient air quality and cleaner air for Europe.
  • EU Adaptation Strategy Package
    In April 2013, the European Commission adopted an EU strategy on adaptation to climate change, which has been welcomed by the EU Member States. The strategy aims to make Europe more climate-resilient. By taking a coherent approach and providing for improved coordination, it enhances the preparedness and capacity of all governance levels to respond to the impacts of climate change.
  • WHO Air Quality Guidelines for Europe
    Air quality guidelines. Global update 2005. Particulate matter, ozone, nitrogen dioxide and sulfur dioxide

Key policy question

What are the effects of climate change on ozone concentrations across Europe and how can they affect health via population exposure?



Methodology for indicator calculation

Data on ozone concentrations is taken from AirBase (the European air quality database). From hourly data, the maximum daily 8-hour mean is calculated for every station that has levels of valid data upwards of 75 %. An annual average is calculated for every type of station (traffic, meaning urban, suburban and rural traffic stations; urban, meaning urban and suburban background stations; rural, meaning rural background stations; and others, meaning stations not falling in the previous categories, mostly industrial stations; see EU, 1997 for classification).

An ensemble of three-dimensional Chemistry Transport Models was used to study the impact of climate change on surface ozone. By comparing modelled ozone using future and present climate, while keeping anthropogenic emissions of ozone precursors constant, the absolute and relative climate ozone penalty can be computed. There have been a dozen of journal articles presenting such results for Europe over the past ten years. A combination of published projections has been used to calculate the multi-model ensemble mean climate impact on surface ozone. Among the 25 available model projections covering various scenarios and time horizons, the results for a median climate scenario (the A1B in the SRES set of scenarios (Nakicenovic et al., 2000)), which is covered by 9 and 3 models for the middle and the end of the century, respectively (Colette et al., 2015) is shown.

Finally, the respective contribution of the main factors influencing the future evolution of surface ozone can be quantified on the basis of air quality modelling sensitivity experiments, where the contributing factors are frozen to their present or future conditions. Such contributing factors are: (i) climate change, (ii) emissions of air pollutants, (iii) long range transport. Approximately one hundred years of simulation were required for such an assessment, given the number of combinations required to explore various possible options, and the fact that, for climate impact assessment, multi-annual simulations are needed (Colette et al., 2013).

Methodology for gap filling

Not applicable

Methodology references

  • Colette, A., B. Bessagnet, R. Vautard, S. Szopa, S. Rao, S. Schucht, Z. Klimont, L. Menut, G. Clain, F. Meleux, G. Curci and L. Rouïl, European atmosphere in 2050, a regional air quality and climate perspective under CMIP5 scenarios, Atmos. Chem. Phys. 13 (2013), pp. 7451-7471.
  • Colette, A., C. Andersson, A. Baklanov, B. Bessagnet, J. Brandt, J. H. Christensen, R. Doherty, M. Engardt, C. Geels, C. Giannakopoulos  G.  B. Hedegaard , E. Katragkou,  J. Langner, H. Lei, A. Manders, D. Melas, F. Meleux, L. Rouïl, M. Sofiev, J. Soares, D. S. Stevenson, M. Tombrou-Tzella, K. V. Varotsos, P. Young,  Is the ozone climate penalty robust in Europe?, Environmental Research Letters, 10 (2015) 084015 .
  • EU, 1997, Council Decision 97/101/EC on the exchange of information and data on ambient air quality,replaced by (EU, 2011).
  • EU, 2011 Commission Implementing Decision 2011/850/EU laying down rules for Directive 2004/107/EC and 2008/50/EC of the European Parliament and of the Council as regards the reciprocal exchange of information and reporting on ambient air.
  • Nakicenovic, N., J. Alcamo, G. Davis, B. de Vries, J. Fenhann, S. Gaffin, K. Gregory, A. Grubler, T.Y. Jung, T. Kram, E.L. La Rovere, L. Michaelis, S. Mori, T. Morita, W. Pepper, H.M. Pitcher, L. Price, K. Riahi, A. Roehrl, H.-H. Rogner, A. Sankovski, M. Schlesinger, P. Shukla, S.J. Smith, R. Swart, S. van Rooijen, N. Victor and Z. Dadi, Special Report on Emissions Scenarios: a special report of Working Group III of the Intergovernmental Panel on Climate Change, Cambridge University Press’, New York (2000) Medium: ED; Size: vp. pp.

Data specifications

EEA data references

Data sources in latest figures



Methodology uncertainty

As with other types of climate impact assessment, uncertainty is addressed by using multi-model ensembles. Statistical significance of the change was assessed with a p-value threshold of 0.05, and the change is considered robust when two-thirds of the models agree.

Data sets uncertainty

Ozone data is officially submitted by the national authorities. It is expected that data has been validated by the national data supplier and it should be in compliance with data quality objectives as described in the 2008 Air Quality Directive. There are different methods in use for the routine monitoring of pollutants.

Station characteristics and representativeness are, in some cases, insufficiently documented.

Further information on uncertainties is provided in Section 1.7 of the EEA report on Climate change, impacts, and vulnerability in Europe 2012 (

Rationale uncertainty

No uncertainty has been specified

Further work

Short term work

Work specified here requires to be completed within 1 year from now.

Long term work

Work specified here will require more than 1 year (from now) to be completed.

General metadata

Responsibility and ownership

EEA Contact Info

Alberto Gonzalez Ortiz


European Environment Agency (EEA)


Indicator code
CLIM 006
Version id: 3
Primary theme: Air pollution Air pollution

Frequency of updates

Updates are scheduled every 4 years


DPSIR: Impact
Typology: Descriptive indicator (Type A - What is happening to the environment and to humans?)


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