The ozone pollution in Europe

The implementation of Directive 92/72/EEC has led to the installation of stations measuring ozone increasing. The directive calls for particular stations to be placed in sites where the risk of approaching or exceeding the information threshold or alert is the highest. Ozone concentrations are highest in summer meet, due to more intense sunlight. From April to August 2005, the frequency of exceedances is comparable to previous years. The maximum time was reached in Portugal (361 ug/m3). Hourly averages between 300 and 360 μg/m3 were registered in France, Greece, Italy and Spain. The alert threshold of 240 μg/m3 as an hourly average was exceeded for 127 hours in nine countries (Austria Belgium, France, Germany, Greece, Italy, Netherlands, Portugal and Spain).
The alert threshold of 240 μg/m3 as an hourly average was exceeded for 127 hours in nine countries (Austria, Belgium, France, Germany, Greece, Italy, Netherlands, Portugal and Spain). The information threshold of population of 180 microgramme/m3 average time has been exceeded during the summer of 2005 in all member states of the EU except in Cyprus, Denmark, Finland, Ireland, Latvia, Lithuania and Sweden. Thus, 3 056 exceedances of information have been observed in 794 stations from a total of 1 865. In the other Member States, the number of days with at least one exceedance was observed during summer 2005 ranged from 1 in Estonia to 86 in Italy. He was 54 in France. Across the European Union, 794 stations (42%) experienced at least one exceedance (against 36% in 2001 and 25% in 2000).

Critical levels of ozone for protecting vegetation

Ozone is a secondary pollutant formed under the effect of solar ultraviolet acting on precursors (NOx, NMVOC, CO). The impact of pollution on ecosystems arises when concentrations exceed certain thresholds. The high ozone concentrations can affect key physiological processes of plants (photosynthesis, respiration) and reduce the production plant. AOT40 (Accumulated Over Threshold of 40 ppb) is an indicator of exposure of plants to the ozone. It represents the accumulated concentrations exceeding the threshold of 40 ppb (parts per billion), or 80 μg/m3.h during the period of plant growth and during daylight hours. The daylight hours are defined as the hours when global radiation received by the Earth are at least 50 Watt/m2. For crops and natural vegetation that have sensitivities to ozone equivalent, the calculation is carried out between May 1 and July 31. For forests, the AOT40 is determined for the period 1 April to 30 September.
The goal of protection of vegetation and crops (6 000 μg/m3.h three months) has been exceeded in most rural sites in 2005. Especially in rural sites in southern and eastern countries that we meet the highest standards. Conversely, western countries experiencing levels generally below the goal of protection of vegetation and crops. The target value (18 000 μg/m3.h) was exceeded mainly in the south due to a combination of factors favorable to ozone production: strong sunshine, traffic and industries supporting the production of precursors.