Indicator Assessment

Air pollution by ozone and health

Indicator Assessment

Prod-ID: IND-94-en

Also known as: CLIM 006

Published 22 Nov 2012 Last modified 11 May 2021

12 min read

This page was archived on 21 Dec 2015 with reason: Other (New version data-and-maps/indicators/air-pollution-by-ozone-2/assessment was published)

Ozone is both an important air pollutant and a GHG. Excessive exposure to ground-level ozone is estimated to cause about 20000 premature deaths per year in Europe.
Attribution of observed ozone exceedances, or changes therein, to individual causes, such as climate change, is difficult.
Future climate change is expected to increase ozone concentrations but this effect will most likely be outweighed by reduction in ozone levels due to expected future emission reductions.

Annual mean ozone concentrations by station type

Note: Annual mean ozone concentrations by station type

Data source:

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Modelled change in tropospheric ozone concentrations over Europe

Note: The modelled changes shown are only due to climate variability and climate change

Data source:

Andersson, C.; Langner, J. and Bergström, R., 2007. Interannual variationand trends in air pollution over Europe due to Climate variability during 1958-2001 simulated with a regional CTM coupled to the ERA40 reanalysis, Tellus 59B: 77-98.

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Past trends

There is no clear trend in the annual mean concentration of ozone recorded at different types of stations (urban vs. rural) over the period 1999–2009, although there is a slight decreasing tendency since 2006 in rural stations, at various geographical levels, both low-level and high-level (Figure 1). Meanwhile, a slight tendency towards increased annual mean concentrations is detected close to traffic. Ozone precursor emissions in Europe have been cut substantially recently whereas average ozone concentrations in Europe have largely stagnated. Meteorological variability and climate change could play a role in this discrepancy, including by increasing emissions of biogenic non-methane volatile organic compounds (NMVOCs) during wildfires, but increasing intercontinental transport of ozone and its precursors in the Northern Hemisphere also needs to be considered [i]. Formation of tropospheric ozone from increased concentrations of CH₄ may also contribute to the sustained ozone levels in Europe [ii].

The relative contributions of local or regional emission reduction measures, specific meteorological conditions (such as heat waves), hemispheric transport of air pollution and emissions from natural sources (such as wildfires), on overall ozone concentrations is difficult to estimate. A statistical analysis of ozone and temperature measurements in Europe for 1993–2004 shows that in central-western Europe and the Mediterranean area a change in the increase in daily maximum temperatures in 2000–2004 compared with 1993–1996 contributed to extra ozone exceedances. In southern and central Europe, the observed temperature trend was responsible for 8 extra annual exceedance days (above the threshold of 120 μg/m³) on average, which corresponds to 17 % of the total number of exceedances observed in that region [iii]. A modelling study suggests that observed climate variability and change have contributed to increased ozone concentrations during the period 1979–2001 in large parts of central and southern Europe (Andersson et al., 2007). The reason for this is a combination of changes in temperature, wind patterns, cloud cover and atmospheric stability. Temperature plays a role in various processes which directly affect the formation of ozone, like the emission of biogenic NMVOCs, for example isoprene, and the photo-dissociation of nitrogen dioxide (NO₂).

A study by [iv] showed that ozone trends in Europe in the years 1997–1998 were influenced by El Niño and biomass burning events and in the year 2003 by the heat wave in north-west Europe. The study did not conclude on the impact of emission reduction on long-term ozone trends, due to the influence of meteorological variability, changes in background ozone and shift in emission source patterns. Decreased anthropogenic emissions of some ozone precursors (NO_X, CO, and some NMVOCs) in the past two decades have reduced the number of peak ozone concentrations [v].

In order to understand historical tropospheric ozone trends, further retrospective sensitivity analysis of precursor emission changes and hindcast modelling of ozone concentrations are needed to quantify the impact and variability of the various factors influencing ozone levels. Figure 2 shows the estimated trends in tropospheric ozone concentrations over Europe for two time periods derived from such hindcast modelling. There has been a marked increase in ozone concentrations in many regions from 1978 to 2001. However, taking into account a longer perspective starting from 1958, increases are limited to a few European regions. Unfortunately, more recent data is not available.

Projections

Climate change is expected to affect future ozone concentrations due to changes in meteorological conditions, as well as due to increased emissions of specific ozone precursors (e.g. increased isoprene from vegetation under higher temperatures) and/or emissions from wildfires that can increase under periods of extensive drought. Most of the links between individual climate factors and ozone formation are well understood (see Table 1 below) [vi]. Nevertheless, quantification of future levels of ground-level ozone remains uncertain due to the complex interaction of these processes. Available studies indicate that projected climate change affects different regions in Europe differently, by increasing average summer ozone concentrations in southern Europe and decreasing them over northern Europe and the Alps [vii]. Preliminary results indicate that in a long time perspective (2050 and beyond), envisaged emission reduction measures of ozone precursors have a much larger effect on concentrations of ground-level ozone than climate change [viii]. Climate change in combination with the emission reductions will influence the future levels of ground-level ozone.

Table 1 Selection of meteorological parameters that might increase under future climate change and their impact on ozone levels

Increase in ...	Results in ...	Impacts on ozone levels ...
Temperature	Faster photochemistry	Increases (high NOx) Decreases (low NOx)
	Increased biogenic emissions (VOC, NO)	Increase
Atmospheric humidity	Increased ozone destruction	Increases (high NOx) Decreases (low NOx)
Drought events	Decreased atmospheric humidity and higher temperatures	Increases
	Plant stress and reduced stomata opening	Increases
	Increased frequency of wild fires	Increases
Blocked weather patterns	More frequent episodes of stagnant air	Increases
	Increase in summer/dry season heat waves	Increases

Source: [ix]

[i] EEA, Air Pollution by Ozone Across Europe During Summer 2009 EEA Technical report (Copenhagen: European Environment Agency, 2010), http://www.eea.europa.eu/publications/air-pollution-by-ozone-across-europe-during-summer-2009; EEA, The European Environment – State and Outlook 2010: Air Pollution — SOER 2010 Thematic Assessment (Copenhagen: European Environment Agency, 2010), http://www.eea.europa.eu/soer/europe/air-pollution.

[ii] EEA, Air Pollution by Ozone Across Europe During Summer 2011 EEA Technical report (Copenhagen: European Environment Agency, 2012), http://www.eea.europa.eu/publications/air-pollution-by-ozone-2011.

[iii] EEA, Impacts of Europe’s Changing Climate - 2008 Indicator-based Assessment. Joint EEA-JRC-WHO Report EEA Report (Copenhagen: European Environment Agency, 2008), http://www.eea.europa.eu/publications/eea_report_2008_4.

[iv] R. C. Wilson et al., “Have Primary Emission Reduction Measures Reduced Ozone Across Europe? An Analysis of European Rural Background Ozone Trends 1996–2005,” Atmospheric Chemistry and Physics 12, no. 1 (January 9, 2012): 437–454, doi:10.5194/acp-12-437-2012.

[v] EEA, Air Quality in Europe — 2011 Report EEA Technical report (Copenhagen: European Environment Agency, 2011), http://www.eea.europa.eu/publications/air-quality-in-europe-2011; EEA, Air Pollution by Ozone Across Europe During Summer 2011.

[vi] Daniel J. Jacob and Darrell A. Winner, “Effect of Climate Change on Air Quality,” Atmospheric Environment 43, no. 1 (January 2009): 51–63, doi:10.1016/j.atmosenv.2008.09.051; P.S. Monks et al., “Atmospheric Composition Change – Global and Regional Air Quality,” Atmospheric Environment 43, no. 33 (October 2009): 5268–5350, doi:10.1016/j.atmosenv.2009.08.021.

[vii] C. Andersson and M. Engardt, “European Ozone in a Future Climate: Importance of Changes in Dry Deposition and Isoprene Emissions,” Journal of Geophysical Research 115, no. D2 (January 22, 2010), doi:10.1029/2008JD011690; J. Langner, M. Engardt, and C. Andersson, “European Summer Surface Ozone 1990-2100,” Atmospheric Chemistry and Physics Discussions 12, no. 3 (March 16, 2012): 7705–7726, doi:10.5194/acpd-12-7705-2012.

[viii] J. Langner, M. Engardt, and C. Andersson, “Modelling the Impact of Climate Change on Air Pollution over Europe Using the MATCH CTM Linked to an Ensemble of Regional Climate Scenarios,” in Air Pollution Modelling and Its Application XXI, ed. Douw G. Steyn and Silvia Trini Castelli, vol. 4 (Dordrecht: Springer Netherlands, 2011), 627–635, http://www.springerlink.com/index/10.1007/978-94-007-1359-8_103.

[ix] Royal Society, Ground-level ozone in the 21st century: future trends, impacts and policy implications. Fowler, D. (Chair) Science Policy Report (London: The Royal Society, 2008), http://royalsociety.org/policy/publications/2008/ground-level-ozone/.

Supporting information

Indicator definition

Annual mean ozone concentrations by station type

Modelled change in tropospheric ozone concentrations over Europe

Selection of meteorological parameters that might increase under future climate change and their impact on ozone levels

Units

µg/m³
% per decade

Rationale

Justification for indicator selection

Ozone is a greenhouse gas, but ground level ozone is primarily an air pollutant, which is of high concern in Europe. 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. Ground-level ozone is highly reactive and therefore harmful to vegetation, materials and human health. Short-term, high-level exposure can cause breathing problems and lung diseases, trigger asthma, and reduce lung function. The estimated effects of excessive exposure to ozone (exceeding the threshold of 70 μg/m³) include about 20 000 premature deaths , and 14 000 respiratory hospital admissions every year in the EU25, and up to 108 million person-days with minor activity restrictions, respiratory medication use, cough or lower respiratory symptoms. Evidence of chronic effects (asthma and lung development) of long-term exposure to high ozone levels is still limited). There is a scarce evidence that high ozone levels can further increase mortality during heat waves.

Scientific references

UNECE 2011: Hemispheric Transport of Air Pollution 2010. Part A. Ozone and Particulate Matter HTAP 2010 is the first comprehensive assessment of the state of the science with respect to the intercontinental transport of air pollutants in the Northern Hemisphere. Information on the development and evolution of the assessment can be found on the HTAP wiki at http://htap.icg.fz-juelich.de/data/Assess2010
WHO 2008: Health Risks of Ozone from Long-range Transboundary Air Pollution Derwent, D.; Forsberg, B.; Amann, M., eBook ISBN: 9289042907 Print ISBN: 9289042893

Policy context and targets

Context description

In April 2013 the European Commission presented the EU Adaptation Strategy Package (http://ec.europa.eu/clima/policies/adaptation/what/documentation_en.htm). This package consists of the EU Strategy on adaptation to climate change /* COM/2013/0216 final */ 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 European Commission and the European Environment Agency have developed the European Climate Adaptation Platform (Climate-ADAPT, http://climate-adapt.eea.europa.eu/) to share knowledge on observed and projected climate change and its impacts on environmental and social systems and on human health; on relevant research; on EU, national and subnational adaptation strategies and plans; and on adaptation case studies.

Targets

No targets have been specified.

Methodology

Methodology for indicator calculation

Observations are shown from AirBase (The European air quality database).

A three-dimensional Chemistry Transport Model was used to study the meteorologically induced interannual variability and trends in concentrations of surface ozone over Europe during 1958–2001.

Methodology for gap filling

Not applicable

Methodology references

Andersson et al. (2007): Interannual variation and trends in air pollution over Europe due to climate variability during 1958–2001 simulated with a regional CTM coupled to the ERA40 reanalysis Tellus B, Vol 59, No 1 (2007), DOI: 10.1111/j.1600-0889.2006.00196.x

Uncertainties

Methodology uncertainty

Not applicable

Data sets uncertainty

Attribution of health effects to climate change is difficult due to the complexity of interactions, and potentially modifying effects of a range of other factors (such as land use changes, public health preparedness, and socio-economic conditions). Criteria for defining a climate-sensitive health impact are not always well identified and their detection sometimes relies on complex statistical or modelling studies (e.g. health impacts of heat waves). Furthermore, these criteria as well as the completeness and reliability of observations may differ between regions and/or institutions, and they may change over time. Data availability and quality is crucial in climate change and human health assessments, both for longer term changes in climate-sensitive health outcomes, and for health impacts of extreme events. The monitoring of climate-sensitive health effects is currently fragmentary and heterogeneous. All these factors make it difficult to identify significant trends in climate-sensitive health outcomes over time, and to compare them across regions. In the absence of reliable time series, more complex approaches are often used to assess the past, current or future impacts of climate change on human health.

Further information on uncertainties is provided in Section 1.7 of the EEA report on Climate change, impacts, and vulnerability in Europe 2012 (http://www.eea.europa.eu/publications/climate-impacts-and-vulnerability-2012/)