European Environment Agency (EEA)

Air pollution by ozone in Europe in summer 2005


Courtesy of Courtesy of European Environment Agency (EEA)

Ground-level ozone is one of the air pollutants of most concern in Europe. Ozone pollution is produced by photochemical processes involving nitrogen oxides and volatile organic compounds in the lower parts of the atmosphere. Ozone levels become particularly high in regions close to high ozone precursor emissions and during summer when stagnant meteorological conditions with high insolation and high temperatures persist. Levels continue to exceed both target values and the long-term objectives established in EU legislation to protect human health and prevent damage to ecosystems, agricultural crops and materials.

This report provides an evaluation of ground-level ozone pollution in Europe for April–September 2005 based on information submitted to the European Commission under Directive 2002/3/EC on ozone in ambient air. Since the submitted data have not yet been finally validated by the Member States, the conclusions drawn in this report should be considered as preliminary.

Directive 2002/3/EC requires the Member States to report exceedances of the information threshold and alert threshold values (see Table 1) to the Commission before the end of the month following an occurrence. Furthermore, by 31 October each year they must provide some additional information for the summer period. This information should include in particular exceedances of the long-term objective for the protection of human health (daily maximum 8-hour average concentrations of 120 μg/m3).

In order to provide information as timely as possible, the summaries of the monthly data provided by the countries were made available on the European Topic Centre on Air and Climate Change website ( as they came in.

Overview of ozone air pollution in summer 2005

All 25 EU Member States either provided information to the European Commission on observed exceedances or indicated by the deadline that no exceedances had been observed. In addition, eight other countries (Bulgaria, Iceland, Liechtenstein, FYR of Macedonia, Norway, Romania, Switzerland and Turkey) supplied information upon request from the European Environment Agency.

In summer 2005, exceedances of the long-term objective for the protection of human health for ozone were observed in almost every country, in almost every summer month and at most of the stations. Exceedances of the target value to protect human health (more than 25 occurrences of daily maximum 8-hour average concentrations of ozone higher than 120 μg/m3) were observed in 16 EU Member States (Austria, Belgium, Cyprus, Czech Republic, France, Germany, Greece, Hungary, Italy, Malta, Poland, Portugal, Slovak Republic, Slovenia, Spain and Sweden) and in two other countries (Bulgaria and Switzerland).

Detailed findings

From a total of 1 931 ozone monitoring sites reporting data, 1 865 were located in EU Member States. The following preliminary conclusions can be drawn for the period April–September 2005:

Exceedance of the information threshold

  • The number of exceedances of information threshold values (180 μg/m³ of one-hour ozone concentration) was similar to previous years, but not as high as those in the record year 2003. Ozone concentrations higher than the information threshold were reported from monitoring sites in 18 EU Member States and four other countries. The information threshold was exceeded at about 42 % of all operational stations (68 % in 2003, 35 % in 2004).
  • The spatial extent of the exceedances observed was larger than in 2004. The most frequent exceedances of the information threshold were observed in northern Italy, southern France and at several locations in Portugal, Spain, Greece and FYR of Macedonia. Most of western and southern Europe recorded at least one day with exceedance in summer 2005. Most of central Europe was without any recorded exceedance.

Exceedance of the alert threshold

  • Ozone concentrations higher than the alert threshold of 240 μg/m³ were reported on 127 occasions in nine EU Member States (Austria, Belgium, France, Germany, Greece, Italy, the Netherlands, Portugal and Spain) and two other countries (Romania and Switzerland). In comparison, 13 of EU-15 Member States and two other countries reported exceedances of the alert threshold in 2003, and eight and four respectively in 2004.
  • The exceedances were found largely in northern Portugal, southern France, northern Italy, Belgium, the Netherlands and Luxembourg. Generally, there were only one or two days with an exceedance of the alert threshold per station.

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