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 47 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 2008/2009 winter period average concentration at any of these stations (Table II.4.2.22).

Fig. II.4.2.48 demonstrates the significant improvement of air quality with regard to sulphur dioxide after 1997 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 both due to more favourable meteorological and dispersion conditions and due to emissions reduction. In the winter periods 2007/2008 and 2008/2009 the levels of air pollution were roughly comparable (Fig. II.4.2.48).

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 2008 annual average concentrations and for the winter average concentration in the winter period 2008/2009. 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, 2008/2009

Fig. II.4.2.45 Annual average concentrations of SO₂ in 1998–2008 at selected rural stations

Fig. II.4.2.46 Winter average concentrations of SO₂ in 1998/1999–2008/2009 at selected rural stations

Fig. II.4.2.47 Field of annual average concentration of SO₂ in 2008

Fig. II.4.2.48 Field of average concentration of SO₂ in the winter period 2008/2009

Fig. II.4.2.49 24-hour concentrations at the stations with the highest annual concentrations of SO₂ in 2008

Fig. II.4.2.50 24-hour concentrations at the stations with the highest winter concentrations of SO₂ in the winter period 2008/2008

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 NO_x with regard to ecosystems and vegetation protection. In 2008 the NO_x air pollution limit value for annual average concentrations (30 μg.m^-3) was not exceeded in any of 46 localities classified as rural. Both the table and the map for NO_x include also the rural stations measuring NO₂, as for the rural stations NO_x concentrations correspond approximately to NO₂ concentrations, in other words, the difference between both concentrations is negligible.

In 2008 annual average NO_x concentrations at most rural stations were comparable with those in the previous year (Fig. II.4.2.51). As it is evident from the map in Fig. II.4.2.52, rural localities did not record the exceedance of the NO_x concentration limit value for the protection of ecosystems and vegetation in 2008.

The construction of the map of the spatial distribution of annual average NO_x 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 is significant. The higher NO_x 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 NO_x concentrations all stations measuring NO_x 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 NO_x 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 NO_x and NO₂ concentrations at rural stations

Fig. II.4.2.51 Annual average concentrations of NO_x and NO₂ in 1998–2008 at selected stations

Fig. II.4.2.52 Field of annual average concentration of NO_x in 2008

Fig. II.4.2.53 24-hour concentrations at the stations with the highest annual concentrations of NO_x in 2008

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 AOT40 . The survey of stations with the highest values of AOT40 is given in Table II.4.2.24.

Of the total number of 35 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 25 localities in 2008 (the average for the years 2004–2008).

As compared with the previous assessment for the period 2003–2007, the values of the exposure index decreased in most localities (32). This was caused mainly by the fact that the assessed 5-year period did not include the year 2003 with long-term high temperatures, high solar radiation values and therefore exceptionally high ground-level ozone concentrations.

The spatial distribution of AOT40 exposure index for the 2008 assessment is shown in the map in Fig. II.4.2.55. Fig. II.4.2.56 presents the AOT40 development in 2004–2008 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 1998–2008 at selected stations, average for 5 years

Fig. II.4.2.55 Field of exposure index AOT40 values, average for 5 years, 2004–2008

Fig. II.4.2.56 Stations with the highest exposure index AOT40 values in recent 5 years, 2003–2008