AIR POLLUTION IN THE CZECH REPUBLIC IN 2009
Czech Hydrometeorological Institute - Air Quality Protection Division



II.4.2.2 Air quality with regard to the limit values for the protection of ecosystems and vegetation

In addition to the limit values for the protection of health the national legislation introduced, in compliance with EU Directives, also the limit values for the protection of ecosystems and vegetation. The survey of the limits is presented Chapter II.3.

II.4.2.2.1 Sulphur dioxide

The results of SO2 air pollution monitoring with regard to the limit value for the protection of ecosystems and vegetation are shown in the Tables II.4.2.21 and II.4.2.22 and in Figs. II.4.2.47 and II.4.2.48. None of the total number of 45 stations, classified as rural, reported the exceedance of the limit value for annual average concentration and there were no exceedances of the limit value for the 2009/2010 winter period average concentration at any of these stations (Table II.4.2.22).

Fig. II.4.2.45 demonstrates the significant improvement of air quality with regard to sulphur dioxide after 1998 in connection with coming into force of the Act No. 309/1991 Coll. and meeting the set emission limit values by the end of 1998. Since then the annual average SO2 concentrations have not exceeded the set limit value 20 μg.m-3 at rural stations. In 2008 there was further decrease of air pollution caused by SO2 on the whole territory of the Czech Republic, in 2009, on the contrary there was recorded very slight increase at most stations.. In the winter period 2009/2010 the levels of air pollution caused by SO2 increased in comparison with the previous period 2008/2009, and namely at the stations of the Moravian-Silesian Region and the Olomouc Region (Fig. II.4.2.46).

The maps in Figs. II.4.2.47 and II.4.2.48 also evidently show that rural localities did not exceed the limit value both for the 2009 annual average concentrations and for the winter average concentration in the winter period 2009/2010. The maps were constructed from the data of all the stations measuring SO2 with regard to their classification; only rural stations are marked with spot symbols.

This chapter is closed by the graphs of courses of 24-hour SO2 concentrations at selected stations, related to the limit value for the winter and annual averages (Figs. II.4.2.49 and II.4.2.50).

Tab. II.4.2.21 Stations with the highest values of annual averages of SO2 concentrations at rural stations

Tab. II.4.2.22 Stations with the highest values of winter averages of SO2 concentrations at rural stations, 2009/2010

Fig. II.4.2.45 Annual average concentrations of SO2 in 1999–2009 at selected rural stations


Fig. II.4.2.46 Winter average concentrations of SO2 in 1999/2000–2009/2010 at selected rural stations


Fig. II.4.2.47 Field of annual average concentration of SO2 in 2009


Fig. II.4.2.48 Field of average concentration of SO2 in the winter period 2009/2010


Fig. II.4.2.49 24-hour concentrations at the stations with the highest annual concentrations of SO2 in 2009


Fig. II.4.2.50 24-hour concentrations at the stations with the highest winter concentrations of SO2 in the winter period 2009/2010


II.4.2.2.2 Nitrogen oxides

Table II.4.2.23 and Figs. II.4.2.51–II.4.2.52 present the situation of ambient air pollution caused by NOx with regard to ecosystems and vegetation protection. In 2009 the NOx air pollution limit value for annual average concentrations (30 μg.m-3) was not exceeded in any of 49 localities classified as rural. Both the table and the map for NOx include also the rural stations measuring NO2, as for the rural stations NOx concentrations correspond approximately to NO2 concentrations, in other words, the difference between both concentrations is negligible.

In 2009 the annual average NOx concentrations at most rural stations increased very slightly (Fig. II.4.2.51). As it is apparent from the map in Fig. II.4.2.52, rural localities did not record the exceedance of the NOx concentration limit value for the protection of ecosystems and vegetation in 2009.

The construction of the map of the spatial distribution of annual average NOx concentrations is based on the combination of measurement and modelling results and also national traffic census from the year 2005 was regarded; as compared with the previous census in 2000 the increase of traffic volume is significant. The higher NOx concentrations can occur also in the vicinity of local communications in the villages with intensive traffic and dense local transport network, where there is no measurement of concentrations. For the construction of the map of the field of NOx concentrations all stations measuring NOx were used, including the rural stations measuring NO2. The spot symbols highlight only the rural stations.

This chapter is closed by the graphs of courses of 24-hour NOx concentrations at selected stations, related to the limit value for the annual average (Fig. II.4.2.53).

Tab. II.4.2.23 Stations with the highest values of annual average of NOx and NO2 concentrations at rural stations

Fig. II.4.2.51 Annual average concentrations of NOx and NO2 in 1999–2009 at selected rural stations


Fig. II.4.2.52 Field of annual average concentration of NOx in 2009


Fig. II.4.2.53 24-hour concentrations at the stations with the highest annual concentrations of NOx in 2009


II.4.2.2.3 Ground-level ozone

For the assessment of vegetation protection against ozone exceedances the national legislation uses, in compliance with the respective EU Directive, the exposure index AOT401. The survey of stations with the highest values of AOT40 is given in Table II.4.2.24.

Of the total number of 36 rural and suburban stations for which the AOT40 calculation is relevant according to the legislation, the target value for ozone for the protection of vegetation was exceeded in 22 localities in 2009 (the average for the years 2005–2009).

As compared with the previous assessment for the period 2004–2008, the values of the exposure index slightly decreased in 75 % of rural and suburban localities. Meteorological characteristics for the year 2004 (which was not included in the assessed 5-year period) in comparison with the year 2009 do not definitely explain this slight decrease. It is possible that the mentioned decline of AOT40 may be connected with a certain decrease of the preliminary emissions of ozone precursors in 2009 due to the economic crisis. This is also indicated by the fact that NO2 concentrations decreased in 2009 as compared with the year 2004 in the period May–July for which the AOT40 value is calculated, in 72 % of localities. However, with regard to rather complicated atmospheric chemical reactions during the creation and disintegration of ozone, to its dependence on the absolute amount and the relative share of its precursors in the ambient air, as well as on meteorological conditions, it is difficult to make more detailed comments on the mentioned slight decrease.

The spatial distribution of AOT40 exposure index for the 2009 assessment is shown in the map in Fig. II.4.2.55. Fig. II.4.2.56 presents the AOT40 development in 2005–2009 in selected localities.

Tab. II.4.2.24 Stations with the highest AOT40 values of ozone at rural and suburban stations

Fig. II.4.2.54 Exposure index AOT40 values of ozone in 1999–2009 at selected stations, average for 5 years


Fig. II.4.2.55 Field of exposure index AOT40 values, average for 5 years, 2004–2009


Fig. II.4.2.56 Stations with the highest exposure index AOT40 values in recent 5 years, 2003–2009

1AOT40: accumulated exposure is calculated as the sum of the difference between hourly ozone concentrations and the threshold level of 80 μg.m-3 (= 40 ppb) for each hour when this threshold value was exceeded. Pursuant to the requirements of the Government Order No. 597/2006 Coll. AOT40 is calculated for the period of three months (May to July) measured between 8:00 and 20:00 Central European Time (= 7:00 and 19:00 UTC).