Heatwave sparks smog warnings through Europe
Read more in the EEA report "Europe's environment: the third assessment Chapter 5 - Air pollution ".
Concentrations of damaging ground-level ozone increase when summer sunshine ignites polluting emissions from transport and industry.
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|Current summer seasons ozone exceedances|
|For information on current summer seasons ozone exceedances reported by countries please visit our|
European Topic Centre on Air and Climate Change
Ozone in ambient air is formed by chemical reactions between nitrogen oxides (NOx) and volatile organic compounds (VOC) under influence of sunlight. Ozone concentrations can build up to high values during warm sunny days. Ozone concentrations today are much higher than a century ago due to emissions of NOx and VOC into the atmosphere from traffic, industry and other sources. Ozone is the main product of complex photochemical processes in the lower atmosphere involving oxides of nitrogen and volatile organic compounds as precursors of ozone formation. Ozone is a strong photochemical oxidant. Its elevated concentrations cause serious health problems and damage to ecosystems, agricultural crops and materials.
Map 1. Example of a smog episode: stations which reported an hourly ozone concentration in excess
of 180 µg/m3, 17-19 and 22 June 2002 (all station types)
Source: map produced by the European Topic Centre on Air and Climate Change.
Ozone episodes, periods with elevated concentrations, mainly occur during periods of warm sunny weather. In Mediterranean countries, with prolonged spells of hot and sunny weather during the summer, ozone can quickly be formed and high concentrations can occur in the vicinity of urban centres. In northern Europe, the build-up of ozone is slower due to the more moderate weather conditions. Here, the highest levels are usually found downwind of cities.
The limit values set by the European Union to protect health are exceeded frequently for a large proportion of the EUs population. Estimates for 1999, for example, suggest that 42% of the population was overexposed on 1-25 days, with 12% overexposed for more than 50 days. Only the Northern European countries and Portugal had less than 10 exceedance days. Although emissions of the substances that lead to ground level ozone are dropping, the reductions are unlikely to help meet either todays or tomorrows targets, with north-west Europe expected to experience around 25 exceedance days per year by 2010. This is partly due to emissions in the whole northern hemisphere.
Scientific research has shown that ozone, NOx and VOC can be transported over distances of hundreds or even thousands kilometres. Under the Convention on Long-range Transboundary Air Pollution, countries in Europe and North America have agreed to reduce emissions according to the terms of a number of protocols.
In order to protect human health and the environment, the European Union, in legislation, has set targets and long-term objectives for ozone concentrations and will limit the national emissions of NOx and VOC. The legislation requires that citizens be properly informed about concentrations of ozone and other air pollutants.
More on ozone exceedance (summer 2002) in the EEA report Air pollution by ozone in Europe: Overview of exceedances of EC ozone threshold values during the summer season April-August 2002.
For information on current summer seasons ozone exceedances reported by countries please visit our
European Topic Centre on Air and Climate Change
Other reports from EEA on ozone exceedance in particular and air pollution in general:
- Europe's environment: the third assessment Chapter 5 - Air pollution
- Air quality in Europe: state and trends 1990-99
- Emissions of atmospheric pollutants in Europe, 1990-99
- Exceedance of the EU human health threshold value for ozone in urban areas
- Exposure to fine particles above EC threshold values
- The air quality directives: http://www.europa.europa.eu/comm/environment/air/ambient.htm
- The ozone directive: http://europa.europa.eu/eur-lex/pri/en/oj/dat/2002/l_067/l_06720020309en00140030.pdf
- Legislation on national ozone precursor emissions: http://www.europa.europa.eu/comm/environment/air/ceilings.htm
- Background information on ozone and its effects: http://www.europa.europa.eu/comm/environment/air/documents/pos_paper.pdf
Several institutions are involved in the monitoring of ozone concentrations and can supply more topical information on specific regions.
National and regional web sites on recent ozone concentrations
Forecast web sites of ground-level ozone for regions in Europe
(Often only available in national languages)
|Norwegian stations and |
some European cities
|Denmark and NW Europe||http://www.dmi.dk/vejr/ozon/smog.html|
|NW Europe and |
For references, please go to www.eea.europa.eu/soer or scan the QR code.
This briefing is part of the EEA's report The European Environment - State and Outlook 2015. The EEA is an official agency of the EU, tasked with providing information on Europe’s environment.
PDF generated on 02 Jul 2015, 09:21 PM