II.4.1 Agglomerations

With regard to the Communication of the Air Quality Protection Division of the Ministry of Environment on delineating zones and agglomerations within the territory of the Czech Republic, air quality assessment in the proposed agglomerations (Prague, Brno and the Moravian-Silesian Region) has been treated with more attention since 2005. In addition to the above agglomerations, special attention is paid in the Yearbook also to the zone Ústí nad Labem Region due to the recorded above-the-limit concentrations.

II.4.1.1 Prague

The Capital City of Prague is the area in which a lot of people are exposed to ambient air pollution. Most of the limit values exceedances are connected with significant traffic loads ensuing from the fact that the main routes lead directly through the city centre. In 2006 air pollution concentrations were measured at 23 localities in the territory of Prague (15 CHMI, 8 ZÚ).
In 2006 the PM₁₀ particles concentrations were monitored in Prague in 15 CHMI localities and in 5 ZÚ localities. The most frequent exceedances of 24-hour PM₁₀ limit value (50 μg.m^-3) were recorded in the following localities: Prague 2-Legerova (164x), Prague 8-Karlín (95x) and Prague 9-Vysočany (82x). Of the total number of 16 localities with valid annual average 15 stations recorded 24-hour PM₁₀ limit value exceedances. The annual PM₁₀ limit value (40 μg.m^-3) was exceeded in the following localities: Prague 2-Legerova (61 μg.m^-3), Prague 9-Vysočany (42 μg.m^-3), Prague 8-Karlín (41 μg.m^-3) and Prague 5-Smíchov (40.3 μg.m^-3).
The PM_2.5 particles concentrations were measured in 5 CHMI localities in 2006. In spite of the fact the PM_2.5 air pollution limit value is not yet set, the comparison of the measured concentrations with the proposed limit value (25 μg.m^-3, annual average) is very interesting. The average annual concentrations in Prague localities were as follows: Prague 9-Vysočany 28.3 μg.m^-3, Prague 5-Smíchov 27.2 μg.m^-3, Prague 5-Mlynářka 21.9 μg.m^-3 and Prague 8-Karlín 18.5 μg.m^-3. It is quite evident that if the proposed limit value for PM_2.5 fraction was valid, it would be exceeded at two Prague stations.
The graphs in Fig. II.4.1.1 show the development of courses of PM₁₀ concentrations at selected AMS in Prague with regard to the temperature and wind velocity for the winter periods 2004/2005, 2005/02006 and 2006/2007.
In the given periods the average winter PM₁₀ concentration exceeded the value 40 μg.m^-3 at several AMS. More than 35 exceedances of the 24-hour air pollution limit value were recorded at the AMS Mlynářka and Smíchov in all periods. The both above air pollution characteristics show the marked decreasing trend at the AMS Smíchov and Kobylisy; on the contrary, at AMS Vršovice the increasing trend was recorded. The maximum measured 24-hour concentrations reached the highest values during the winter period 2005/2006, when the lowest average temperature was measured as well.
NO₂ concentrations were measured in 15 localities in Prague in 2006. The AIM station Prague 2-Legerova exceeded the hourly limit value 200 μg.m^-3 but not the hourly limit value plus the margin of tolerance (200+40 μg.m^-3). The value of 200 μg.m^-3 was exceeded 126x, the value of 240 μg.m^-3 was exceeded 8x. The hourly NO₂ concentration 200 μg.m^-3 was exceeded also at AMS station Prague 9-Vysočany (3x) and Prague 10-Vršovice (1x); consequently, the tolerated number of exceedances was not reached.
The annual air pollution limit value plus the margin of tolerance for NO₂ (40+8 μg.m^-3) was markedly exceeded at the AMS Prague 2-Legerova (74 μg.m^-3) and also in the following ZÚ localities: Svornosti in Prague 5 (73 μg.m^-3) and Sokolovská in Prague 8 (60 μg.m^-3).
Another problem is caused by above-the-limit benzo(a)pyrene concentrations which, similarly as in the previous year, exceeded the target value at all (3) stations which measured it in Prague, and namely Prague 10-Šrobárova, Prague 5-Smíchov, Prague 4-Libuš.
The results of the measured concentrations of PM₁₀, NO₂ and benzo(a)pyrene suggest the serious need to find the solution for the traffic situation within the agglomeration.
The exceedances of the target value for the ground-level ozone was also recorded. It was exceeded in 3 of 7 localities in Prague, which have carried out the measurements in the recent three years at least for the period of one year (pursuant to the definition of the target value in the Government Order).

Fig. II.4.1.1 PM₁₀ air pollution characteristics for monitoring stations and basic characteristics of meteorological conditions in the winter period (October–March) 2004/05, 2005/06 and 2006/07, Prague agglomeration, 2006

Fig. II.4.1.2 Field of the annual concentration of NO₂, Prague agglomeration, 2006

Fig. II.4.1.3 Field of the annual concentration of benzo(a)pyrene, Prague agglomeration, 2006

 

II.4.1.2 Brno

In the Brno agglomeration, similarly as in the Prague agglomeration, the most serious air pollution problems are caused by high density of population connected with ever increasing intensity of traffic. This results mainly in the increased PM₁₀ (PM_2.5) particles and benzo(a)pyrene concentrations in the ambient air.
The ISKO database receives the measured concentrations from 4 CHMI stations, from 3 ZÚ stations, and since 2006 also from 5 stations of the Statutory City of Brno.

PM₁₀ concentrations were measured in 7 localities in 2006. The exceedance of the PM₁₀ 24-hour limit value was recorded at AMS Brno-střed which is located in the city centre in the immediate vicinity of the crossroad of two frequented communications. The tolerated number of exceedance of the value 50 μg.m^-3 is 35x in total; the measurements at this station, however, recorded 109 cases of exceedance, i.e. almost one third of the days in the given year. The limit value was further exceeded in the localities Brno-Tuřany (69x), Brno-Lány (63x) and Brno-Kroftova (54x). The locality Brno-Kroftova is also influenced by traffic. The localities Brno-střed and Brno-Kroftova also exceeded the PM₁₀ annual limit value.
The only locality in Brno measuring the PM_2.5 fraction concentration in 2006, and namely Brno-Tuřany, would exceed the proposed limit value, as it recorded the annual average 27.6 μg.m^-3.
The NO₂ annual limit value plus the margin of tolerance was exceeded in the locality Brno-Svatoplukova, the locality Brno-střed recorded only the limit value exceedance. The hourly limit value was not exceeded at any station.
In 2006 also the target limit value for benzo(a)pyrene was exceeded in the locality Brno-Kroftova, which as one of the two stations in Brno measured this pollutant.
The concentrations of ground-level ozone were measured in 3 localities in 2006 of which two (Brno-Tuřany and Brno-Zvonařka) exceeded the target limit value for ground-level ozone. The deadline for achieving this limit value is 31.12.2009.

The expanding of the areas with deteriorated air quality within the Brno agglomeration and the South Moravian Region

Recently the extent of the areas with deteriorated air quality has been markedly increasing, both within the Brno agglomeration and the zone South Moravian Region. In 2004 the share of the areas with deteriorated air quality was approx. 4 % of the whole territory of the South Moravian Region, in 2005 and 2006 they covered already about 2/3 of the territory of this region. The increase was caused mainly by a large number of localities with exceedances of the 24-hour PM₁₀ limit value, both in urban localities and in the background localities without industrial and traffic impacts.
The increase of exceedances of limit values in 2005 and 2006, and consequently the extent of the areas with deteriorated air quality, can be explained by very unfavourable dispersion conditions, mainly due to temperature inversions. Very strong temperature inversion influenced the dispersion conditions in the second half of January and in early February of the year 2006 when all stations recorded exceedances of the valid limit values for approx. 20 days. The maximum values of 24-hour PM₁₀ concentrations measured in Brno ranged around 200 μg.m^-3. With regard to the unfavourable meteorological conditions the number of exceedances of the 24-hour PM₁₀ concentration approached the tolerated 35 exceedances as early as in late February 2006. The number of days with exceedances of the limit value (50 μg.m^-3) for the PM₁₀ 24-hour concentration in the winter period (October–March), starting from the year 2000, is shown in the following table. To illustrate the situation, the selected localities are both background: Mikulov-Sedlec in the South Moravian Region, and Brno-Tuřany in the Brno agglomeration.

Tab. II.4.1.1 Number of days with exceedances of the limit value (50 μg.m^-3) for the PM₁₀ 24-hour concentration in the winter period (October–March)

The table illustrates, that the winter 2005/2006 was really extraordinary. The number of days with exceedances of the value 50 μg.m^-3 in the locality Mikulov-Sedlec was more than double in comparison with any of the previous winter periods. In the locality Brno-Tuřany the double number of days with exceedances was not achieved, nevertheless this locality had also the highest number of exceedances of the concentration 50 μg.m^-3 in the winter period 2005/2006.

Significant difference is evident in comparison of the winter periods 2005/2006 and 2006/2007. The following graphs for the localities Mikulov-Sedlec and Brno-Tuřany compare the two winter periods, both with regard to the exceedance of the concentration 50 μg.m^-3 (bar graph) and average monthly concentrations (line graph).

The presented graphs (Fig. II.4.1.4) show that mainly January 2006 was an extraordinary month (e.g. the station Mikulov-Sedlec recorded 19 exceedances in January 2006 and 1 exceedance in January 2007), and the air quality was worse also in the remaining months of the winter period 2005/2006. There was one exception , and namely the month of December in the locality Brno-Tuřany, where the air quality was worse in December 2006 than in December 2005.

Fig. II.4.1.4 24-hour PM₁₀ concentrations and numbers of exceedances of limit value in winter period (October–March) 2005/06 and 2006/07

Fig. II.4.1.5 Field of the annual concentration of NO₂, Brno agglomeration, 2006

Fig. II.4.1.6 Field of the annual concentration of benzo(a)pyrene, Brno agglomeration, 2006

II.4.1.3 The Moravian-Silesian Region

The ambient air pollution in the agglomeration Moravian-Silesian Region is connected, in addition to high population density, also with high concentration of industry, and namely in the following cities: Ostrava, Karviná, Havířov, Český Těšín and Třinec.
In 2006 PM₁₀ concentrations were monitored in 25 localities (19 CHMI, 5 ZÚ and 1 MÚ Třinec) in the agglomeration Moravian-Silesian Region. The exceedance of the PM₁₀ 24-hour limit value was reached most frequently at the stations in the districts Karviná and Ostrava-město, then in several parts of the districts Frýdek-Místek, Nový Jičín and Opava. The highest number of exceedances of the value of 50 μg.m^-3 was recorded in the following localities: Český Těšín (186x), Ostrava-Bartovice (172x), Bohumín (169x), Ostrava-Přívoz (149x), Karviná (145x), Ostrava-Českobratrská (144x), Věřňovice (143x), Orlová (141x), Havířov (135x), Karviná-ZÚ (126x), Ostrava-Fifejdy (112x) and Ostrava-Přívoz ZÚ (110x). In total, 23 localities with the valid annual average exceeded the PM₁₀ 24-hour limit value.
The exceedances of the PM₁₀ annual limit value (40 μg.m^-3) were recorded also mostly in the above districts. The highest annual average was recorded at the following localities: (Věřňovice (64 μg.m^-3), Ostrava-Bartovice (64 μg.m^-3), Bohumín (63 μg.m^-3), Český Těšín (61 μg.m^-3), Orlová (58 μg.m^-3), Karviná (57 μg.m^-3), Ostrava-Přívoz (56 μg.m^-3), Havířov (55 μg.m^-3), Ostrava-Českobratrská (54 μg.m^-3), Karviná-ZÚ (48 μg.m^-3) and Ostrava-Fifejdy (47 μg.m^-3). The limit value for annual average was exceeded in 18 localities in this region.
The localities which measured PM_2.5 fraction in 2006 in the Moravian-Silesian Region rank among the top localities as for the highest measured concentrations within the Czech Republic. In the locality Věřnovice the annual average amounted to 50.4 μg.m^-3, in Ostrava-Přívoz 44 μg.m^-3, in Ostrava-Zábřeh 35.1 μg.m^-3 and in Ostrava-Poruba 31.4 μg.m^-3. It is evident that all localities would markedly exceed the proposed limit value.
NO₂ concentrations were measured in total in 27 localities in 2006 (20 CHMI, 4 ZÚ, 2 ČEZ and 1 MÚ Třinec). The AMS Ostrava-Českobratrská (hot spot) recorded the NO₂ annual limit value exceedance; the limit value plus the margin of tolerance was not exceeded.
The highest benzo(a)pyrene concentrations in the Czech Republic in 2006 occurred again in the Moravian-Silesian Region (locality Ostrava-Bartovice). The above-the-limit concentrations were measured in all 6 localities which measured this pollutant in 2006.
Another problem is caused by the high benzene concentrations which, similarly as in the previous year, exceeded the limit value (as the only ones in the Czech Republic) in both localities with the highest industrial loads, i.e. Ostrava-Přívoz (ZÚ and CHMI). In 2006 benzene concentrations were monitored in 7 localities of the Moravian-Silesian Region.
In 5 localities (of the total number of 7) the target limit values for ground-level ozone was exceeded as well, mainly in localities with lower traffic loads, and namely: Červená, Bílý kříž, Třinec Kosmos, Ostrava-Fifejdy and Karviná.
The target value for arsenic was also exceeded at 2 localities with the highest air pollution loads (Ostrava-Bartovice and Ostrava-Mariánské Hory). Arsenic concentrations were monitored in 11 localities in the Moravian-Silesian Region in 2006.
The following text presents the detailed description of unfavourable situation of January 2006 which resulted in significant increase of air pollution concentrations in the Moravian-Silesian Region.

Unfavourable air pollution situation in the Moravian-Silesian agglomeration in January 2006
In the first week of January 2006 the territory of the Czech Republic was influenced by the extending anticyclone with the centre above north-eastern Europe and by the abating relatively strong precipitation from December 2005/January 2006 which caused the continuous and relatively rich snow cover in the whole territory of northern Moravian and Silesia. The minimum temperatures ranged between –1 and –6 �C, the maximum temperatures very slightly exceeded 0 �C (not at all stations). At the end of the week the centre of the anticyclone moved moderately to the west above the Baltic area and southern Scandinavia. This was connected with lower precipitation and lower cloudiness which consequently, resulted in significant decrease of minimum daily temperatures. On 7 January the minimum morning temperatures ranged between –10 and –15 �C in lower altitudes, while in higher altitudes, due to the strengthening inversion character of the whole situation, the temperatures ranged around only –8 �C. The velocity of ground-level airflow decreased, especially in lower altitudes (average wind velocity measured at the stations in 10 m above the ground did not exceed 2 m.s^-1 in most cases). The situation lasted for several following days. Beginning from 11 January the influence of the anticyclone gradually weakened, the inversion character of the weather ceased and the velocity of airflow increased. Significant change of meteorological situation occurred as late as 16 January, when the influence of the anticyclone weakened and individual frontal systems began to enter central Europe from the north-west; they brought the change of character of airflow and precipitation.
The deteriorating dispersion conditions of the ambient air had their most significant impact on the increase of PM₁₀ suspended particles concentrations. In early January the PM₁₀ concentrations remained below, or only slightly exceeded the 24-hour limit value 50 μg.m^-3, on 7 and 8 January, however, most of the stations in both regions recorded much higher concentrations. On 8 January the values ranged between 110 and 408 μg.m^-3 (with the maximum at the station Orlová). The persisting and initially more significant character of inversion situation resulted in further significant increase of concentrations during the following days. The worst air pollution situation occurred on Tuesday, 9 January, when the 24-hour PM₁₀ concentrations ranged between 125 and 732 μg.m^-3, with the highest values reached in the environs of Karviná, Bohumín and Orlová.
With the weakening influence of the anticyclone the PM₁₀ concentrations gradually decreased beginning from 11 January. The marked decrease of PM₁₀ concentrations was recorded after the change of meteorological situation in the week from Monday 16 January when the influence of the anticyclone weakened and the several-day episode of unfavourable air pollution situation came to an end.
The described situation demonstrates quite clearly the dominant influence of current meteorological dispersion conditions on air quality. Fig. II.4.1.7 shows the dependence between air pollution caused by PM₁₀ and the meteorological conditions. (Data on wind velocity in the elevation 200 m and 36 m come from Ostrava, in the elevation 10 m from the AMS Karviná. Vertical temperature gradient of air was determined between the meteorological stations Mošnov (251 m a.s.l.) and Lysá hora (1324 m a.s.l.). Vertical temperature gradient of air quantifies the change of temperature with the change of the elevation. It is expressed in �C per 100 m of height and it is negative during the increasing temperature with the elevation, i.e. temperature inversion.)

With the decline of wind velocity and increasing inversion (characterized by the temperature gradient of air in the figure) the PM₁₀ concentrations increased beginning from 7 January. With the increasing wind velocity between 10 and 11 January the concentrations decreased, however, due to the remaining inversion they were high, and they increased again after the wind velocity reduced. The decisive decline in PM₁₀ concentrations occurred as soon as the airflow increased and, simultaneously, the temperature inversion disappeared. Fig. II.4.1.8 shows the course of average 24-hour PM₁₀ concentrations during the studied period.
Of course, during the unfavourable situation, the dispersion conditions deteriorated for all pollutants in the ambient air, not only for suspended particles. In spite of the fact that PM₁₀ concentrations exceeded the 24-hour air pollution limit value (50 μg.m^-3) in manifold levels, other pollutants recorded only slight exceedances at several stations only or not at all (see Fig. II.4.1.9).
The value of the 1-hour limit value (350 μg.m^-3) for SO₂ was exceeded only for two hours, and namely at the AMS station Ostrava-Zábřeh with the maximum value 389 μg.m^-3; all the remaining values at all AMS did not reach even 2/3 of the limit value, with the exception of two values.
The value of the 24-hour limit value (125 μg.m^-3) for SO₂ was exceeded only on 9 and 10 January at the AMS Věřnovice and on 13 January at the AMS Ostrava-Zábřeh and Ostrava-Poruba (the maximum value of 171 μg.m^-3).
The value of the 1-hour limit value of 200 μg.m^-3 for NO₂ was not exceeded at any AMS; the highest measured concentration was 197 μg.m^-3.
The value of the 8-hour limit value of 10,000 μg.m^-3 for CO was not exceeded at any AMS; even the traffic AMS Ostrava-Českobratrská, which usually has the highest values, reported 5,802 μg.m^-3 as its highest measured value.
Pursuant to the valid legislation (Decree No. 553/2002 Coll., as amended) the conditions for the issuing of neither the signal for the information of the public nor the regulation were fulfilled, i.e. the smog situation did not occur.
The unfavourable air pollution situation in January 2006 showed again that the long lasting unfavourable dispersion conditions for the pollutants in the ambient air result in the increased concentrations of PM₁₀ suspended particles amounting up to manifold levels of the daily limit value. During the January 2006 situation even higher values were measured in comparison with those in similar situation of February 2005.
Another unfavourable air pollution situation with high concentrations of suspended particles started after the income of very cold air on 22 January, again in connection with the massive anticyclone. The increased concentrations lasted until 6 February, the highest concentrations were measured between 23 and 29 January. At most stations, however, the maximum PM₁₀ concentrations during this situation, did not reach the levels of the episode described above in detail.
The concentrations of suspended particles increased also in other areas of the Czech Republic in the described periods.

The relation between air pollution concentrations and meteorological conditions and air pollution in the Ostrava city caused by PM₁₀ particles during the three recent winter periods

The level of air pollution in the respective area and period is significantly influenced by meteorological dispersion conditions. This can be demonstrated e.g. by the assessment of air pollution in the Ostrava city during the three recent winter periods. Very slight character of the latest winter months (December 2006–February 2007) resulted in the relatively favourable situation during the whole period.
The level of air pollution caused by PM₁₀ suspended particles in the territory of Ostrava city during the three recent winter periods is shown in Fig. II.4.1.10, in which 95th percentiles from all daily PM₁₀ concentrations measured on the given days in the territory of the Ostrava city are plotted. To illustrate the situation, unfavourable air pollution episodes of February 2005 and of January 2006 are marked, and for comparison the day with the highest air pollution levels in the latest winter period is also marked.

The first graph in Fig. II.4.1.11 shows the basic characteristics of the level of air pollution caused by PM₁₀ in Ostrava during the three recent winter periods: the average concentrations and relative frequencies of the measured daily concentrations higher than 50 and 100 μg.m^-3 as the percentage of all concentrations measured at the stations in Ostrava in the given winter period. It is evident that the worst air pollution situation occurred in the winter period 2005/2006; the period 2006/2007was relatively most favourable.
Further graphs in Fig. II.4.1.11 show the basic characteristics of meteorological dispersion conditions in the assessed recent three winter periods. The results show quite clearly that air pollution situation reflects the meteorological dispersion conditions. In the winter period 2005/2006 all assessed characteristics testify to the most unfavourable meteorological dispersion conditions, and on the contrary, the winter period 2006/2007 had the most favourable dispersion conditions: winter season 2005/2006 had the lowest average and maximum daily wind velocity and the highest number of days with low winter velocity. On the contrary, the number of days with higher wind velocity was the lowest. The thermal stratification (the assessments used the average values of the temperature pseudogradient between the stations Mošnov and Lysá hora calculated from daily average, minimum and maximum temperatures) was most stable in the winter period 2005/2006, and most unstable, again, in the latest period 2006/2007. The latest winter period 2006/2007 was the warmest winter of the assessed periods, and 2005/2006 was definitely the coldest one.
The graphs in Fig. II.4.1.12 show the PM₁₀ air pollution characteristics for individual stations in Ostrava. The assessed results correspond with the presented conclusions at most stations, with the exception of the ZÚ station Ostrava-Bartovice. This station is located, with regard to the prevailing winds in the Ostrava area, in the leeward side of the large source Mittal Steel Ostrava Co. and whereas the average concentrations for the winter period 2006/2007 recorded at stations in Ostrava ranged between 50 and 60 % of the average concentrations for 2004/2005–2005/2006, station Ostrava-Bartovice reached 83 %. The relative frequency of daily concentrations higher than the value of the daily limit decreased to 24–62 % at the stations in Ostrava in the winter period 2006/2007 as compared with the previous winter periods. In Bartovice, however, it decreased only to 92 %. The results confirm the local influence of the monitored locality, independent of general dispersion conditions in the given region.

Fig. II.4.1.7 Interdependency between PM₁₀ ambient air pollution and dispersion meteorological conditions

Fig. II.4.1.8 Average 24-hour PM₁₀ concentrations, Moravian-Silesian agglomeration, 6.1.–15.1.2006

Fig. II.4.1.9 Comparison of maximum measured concentrations with air pollution limit values. 6.1.–6.1.2006

Fig. II.4.1.10 The level of air pollution caused by PM₁₀ particles on the territory of the city of Ostrava in winter months 2004/05, 2005/06 and 2006/07

Fig. II.4.1.11 Basic characteristics of meteorological conditions in winter months 2004/05, 2005/06 and 2006/07

Fig. II.4.1.12 Air pollution characteristics of the stations in Ostrava in winter months 2004/05, 2005/06 and 2006/07

Fig. II.4.1.13 Field of the annual concentration of NO₂, Moravian-Silesian agglomeration, 2006

Fig. II.4.1.14 Field of the annual concentration of benzo(a)pyrene, Moravian-Silesian agglomeration, 2006

 

II.4.1.4 Other areas with air pollution loads with higher density of population

The Ústí nad Labem Zone

The Ústí nad Labem Region is defined as a zone. This area has high population density and is highly industrialized, and thus a number of pollutants have above-the-limit concentrations.
In 2006, PM₁₀ concentrations were measured in 26 localities (18 CHMI, 7 ZÚ, 1 SŠZE Žatec) in the Ústí nad Labem Region. The exceedances of the 24-hour limit value for PM₁₀ occurred mostly in the Ústí nad Labem, Teplice and Most districts. The highest numbers of exceedances of the value 50 μg.m^-3 were recorded in the following localities: Ústí n.L.-Všebořická (117x), Ústí n.L.-město (87x), Teplice (82x), Most (81x), Lom (79x), Děčín (74x), Žatec (69x), Litoměřice (65x) and Lovosice-MÚ (62x). In total, 15 localities in the Ústí nad Labem Region exceeded the PM₁₀ 24-hour limit value. The exceedance of the PM₁₀ annual limit value was recorded at the following stations: Ústí n.L.-Všebořická (46 μg.m^-3), Ústí n.L.-město (44 μg.m^-3), Teplice (43 μg.m^-3), Most (41 μg.m^-3) and Lom (40.4 μg.m^-3).
The annual average PM_2.5 concentration in the locality Teplice reached the value of 26.8 μg.m^-3 and 25.6 μg.m^-3 in Most. The proposed limit value was thus exceeded in both localities. The annual average concentration reached 23.7 μg.m^-3 in Lom and 22.9 μg.m^-3.in Ústí n.L.-Kočkov.
In 2006 NO₂ concentrations were monitored in 36 localities in the Ústí nad Labem Region (19 CHMI + 17 of other organizations). The station Ústí n.L.-Všebořická and ZÚ station Děčín, which are significantly influenced by traffic, exceeded the annual limit value of NO₂ but not the limit value plus the margin of tolerance.
24-hour limit value for SO₂ was exceeded in 2 localities: Úštěk (8x) and Kostomlaty pod Milešovkou (4x). The hourly SO₂ limit value was not exceeded. Occasionally the exceedances of hourly concentration 350 μg.m^-3 or, in other localities, of 24-hour average concentration 125 μg.m^-3 occurred, in most cases at the stations operated by ČEZ. The number of exceedances, however, remained within the tolerated range.
The target value for benzo(a)pyrene was exceeded at all 4 localities in the Ústí nad Labem Region which measured this pollutant in 2006 (Teplice, Ústí nad Labem-ZÚ, Pasteurova, Most, Ústí n. L.-Kočkov)
The target value for ground-level ozone was markedly exceeded similarly as in other parts of the Czech Republic, and mainly at the stations with lower traffic loads. The exceedances were recorded in 6 localities of the total number of 12 localities.

Increased PM₁₀ concentrations in the north-western Bohemia
The episodes of unfavourable dispersion conditions, which occurred at the beginning of the year 2006 as well as in the previous years, were accompanied in north-western Bohemia by the increased PM₁₀ concentration in the ambient air. Due to the exceedances of the PM₁₀ limit values the large part of the territory of the Ústí nad Labem Region is listed among the areas with deteriorated air quality.
The following tables and figures present the examples and courses of the increased PM₁₀ concentrations in the localities Ústí n. L.-město (urban background) and Ústí n.L.-Kočkov (suburban background), The situation was similar also at other measuring stations in the foothills of the Krušné hory Mts.
It can be seen from the Table II.4.1.2 and Fig. II.4.1.15 that the situations when the PM₁₀ concentrations were exceeding the 24-hour limit value (50 μg.m^-3) for several subsequent days, were relatively frequent in Ústí nad Labem during the monitored period. Fig. II.4.1.16 presents the selected episodes with the occurrence of the highest concentrations, during which the measured levels of the PM₁₀ 24-hour limit value (50 μg.m^-3) were multiple for several days, and the average daily PM₁₀ concentration reached on at least 4 days the value of 100 μg.m^-3 and on at least one day it was not lower than 150 μg.m^-3.

Tab.II.4.1.2 The assessment of the measured PM₁₀ concentrations, localities Ústí n.L.-město and Ústí n.L.-Kočkov, 2004–2006

Fig. II.4.1.15 Course of 24-hour concentrations of PM₁₀, Ústí n.L.- Kočkov and Ústí n.L.-město, 2004–2006

Fig. II.4.1.16 Average 24-hour concentration of PM₁₀, Ústí n.L.-Kočkov and Ústí n.L.-město, 8.1.–19.1.2006 and 22.1.–4.2.2006

 

4.1.5 Trends of annual air pollution characteristics of SO₂, PM₁₀ and NO₂ for the period 1996–2006

Fig II.4.1.17 shows the trends of SO₂, PM₁₀, NO₂ and CO annual air pollution characteristics in 1996–2006 for the following agglomerations: Prague, Brno and Moravian-Silesian Region and for the zone Ústí nad Labem Region.
Up to 1999 there was a significant decreasing trend in SO₂ and PM₁₀ concentrations in the agglomerations, the NO₂ concentrations decreased only slightly. In 2001 the decreasing trend was interrupted and, on the contrary, the SO₂ and NO₂ concentrations slightly increased; PM₁₀ concentrations increased significantly, mainly in the Ostrava agglomeration. In 2004, on the contrary, concentrations of all pollutants monitored in the agglomerations decreased, and SO₂ concentrations slightly increased in the Ústí nad Labem Region. Since 2005 NO₂ air pollution has returned to the increasing trend, which was confirmed in 2006. As concerns PM₁₀, there has been a similar characteristic increasing trend since 2005, with the steepest progress in the Moravian-Silesian Region. In 2006, however, this trend continued only in the Prague and Brno agglomerations. In the Ústí nad Labem Region and in the Moravian-Silesian Region, on the contrary, slight decrease of 24-hour PM₁₀ concentrations and stagnation of annual PM₁₀ concentrations were recorded. In 2006 the prevailing decreasing trend in air pollution caused by SO₂ was interrupted. SO₂ concentrations recorded a slight increase in the agglomerations, and they stagnated in Brno. CO concentrations have remained at similar level since 1999. The highest average concentrations have been regularly measured in the Moravian-Silesian Region since 2000. 

Fig. II.4.1.17 Trends of SO₂, PM₁₀, NO₂ and CO annual characteristics in agglomerations, 1996–2006