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.4.2.43 and
II.4.2.44. None of the total number of
31 stations, classified as rural, reported the exceedance of the limit value for
annual average concentration. Due to very mild winter there were no exceedances
of the limit value for the 2006/2007 winter average concentration at any of
these stations (Table II.4.2.22).
Fig. II.4.2.43 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 averages of SO2 have not exceeded the set limit
value 20 μg.m-3 at rural stations. In the winter period 2006/2007, due to mild
winter and favourable dispersion conditions on the whole territory of the Czech
Republic, air pollution caused by SO2 significantly decreased as compared with
the previous period of 2005/2006 (Fig. II.4.2.44).
The maps in Figs. II.4.2.45 and
II.4.2.46 show that rural localities did not
exceed the limit value both for the 2006 annual average concentrations and for
the winter average concentration in the winter period 2006/2007. The maps were
constructed from the data of all the stations measuring SO2 with the
significance (weight) according to their classification; only rural stations are
marked with spot symbols.
For the year 2006 the Yearbook presents also 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.4.2.47 and
II.4.2.48).
Tab. II.4.2.21 Stations with the highest values of annual average
concentrations at rural stations, SO2
Tab. II.4.2.22 Stations with the highest values of winter averages of SO2
concentrations at rural stations, 2006/2007
Fig. II.4.2.43 Annual average concentrations of SO2 in 1996–2006 at selected
rural stations
Fig. II.4.2.44 Winter average concentrations of SO2 in 1996/1997–2006/2007 at
selected rural stations
Fig. II.4.2.45 Field of annual average concentration of SO2 in 2006
Fig. II.4.2.46 Field of average concentration of SO2 in the winter period
2006/2007
Fig. II.4.2.47 24-hour concentrations at the stations with the highest annual
concentrations of SO2 in 2006
Fig. II.4.2.48 24-hour concentrations at the stations with the highest winter
concentrations of SO2 in the winter period 2006/2007
II.4.2.2.2 Nitrogen oxides
Table II.4.2.23 and Figs.
II.4.2.49–II.4.2.50 present the situation of ambient
air pollution caused by NOx with regard to ecosystems and vegetation protection.
In 2006 the annual NOx limit (30 μg.m-3) was not exceeded in any locality
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 2006 slight increase of annual average NOx concentration occurred at several
rural stations as compared with the previous year, but at other stations, on the
contrary, slight decrease was recorded (Fig. II.4.2.49). As it is evident from
the map in Fig. II.4.2.50, rural localities did not record the exceedance of the
NOx concentration limit value for the protection of ecosystems and vegetation in
2006.
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.
The construction of the map of the field of 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 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.
This part 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.4.2.51).
Tab. II.4.2.23 Stations with the highest values of annual average
concentrations at rural stations, NOx and NO2
Fig. II.4.2.49 Annual average concentrations of NOx and NO2 in 1996–2006 at
selected stations
Fig. II.4.2.50 Field of annual average concentration of NOx in 2006
Fig. II.4.2.51 24-hour concentrations at the stations with the highest annual
concentrations of NOx in 2006
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 33 rural and suburban stations
for which the AOT40 calculation is relevant according to the legislation, the
target value for the protection of vegetation was exceeded at 30 localities in
2006 (the average for the years 2002–2006). Fig. II.4.2.52 shows the values of
AOT40 exposure index in the 5-year average (min. 3 years) at selected stations
in 1996–2006. A slight increase is apparent as a result of the fact that the
year 2006 was warmer by almost 2° C in the period May–July in comparison with
the year 2001 which was not used for the assessment of the 5-year average in
this Yearbook. This resulted in higher ozone concentrations.
The spatial distribution of AOT40 exposure index in 2006 is shown in the map in
Fig. II.4.2.53. It is evident that in the average for the years 2002–2006 exceedances occurred in almost whole territory of the Czech Republic (99.6 %).
Fig. II.4.2.54 presents the AOT40 development in 2002–2006 at selected
stations. Table II.4.2.24 shows the stations with the highest AOT40 values of
ozone at rural and suburban stations in 2006.
Tab. II.4.2.24 Stations with the highest AOT40 values of ozone at rural and
suburban stations
Fig. II.4.2.52 Exposure index AOT40 values of ozone in 1996–2006 at selected
stations, average for 5 years
Fig. II.4.2.53 Field of exposure index AOT40 values, average for 5 years,
2002–2006
Fig. II.4.2.54 Stations with the highest exposure index AOT40 values in recent 5
years, 2002–2006
