II.4.2 Czech Republic

II.4.2.1 Air quality with regard to health protection limit values

II.4.2.1.1 Sulphur dioxide

Sulphur dioxide emitted from anthropogenic sources is created mainly by burning the fossil fuels (mostly coal and heavy fuel oils) and by smelting ores containing sulphur. Volcanos and oceans belong to the main global natural sources of SO₂, nevertheless their share on the territory within EMEP (in which the Czech Republic is also participating) was estimated at only 2 %. In the atmosphere, SO₂ is oxidized to sulphates and H2SO4, creating aerosol both in the form of droplets and suspended particles of broad size range. SO₂ and the substances originating from it are removed from the atmosphere through wet and dry deposition. SO₂ has irritating effect, high concentrations can cause lung function impairment and the change of lung capacity.
The 2006 situation of air pollution caused by SO₂ with regard to the limit values set by the legislation is documented by the Tables II.4.2.1 and II.4.2.2 and Figs. II.4.2.1–II.4.2.4. The table of annual average SO₂ concentrations is also included to illustrate the situation (Table II.4.2.3).
In 2006 the set limit value for 24-hour SO₂ concentration (125 μg.m^-3, tolerated number of exceedances – 3) was exceeded in the locality Úštěk (ZÚ) and at two ČEZ stations Kostomlaty pod Milešovkou and Petrovice u Karviné. The Úštěk locality recorded the exceedances of 1-hour limit value also in previous years due to the influence of local sources. No locality reported the exceedance of the 1-hour SO₂ limit value 350 μg.m^-3 (tolerated number of exceedances – 24, the highest number of exceedances was recorded at the ČEZ AMS station Horní Halže – 9).
The map diagrams in Fig. II.4.2.1 show the evident improvement of air quality resulting from the significant decrease of SO₂ concentrations documented by the marked decline of the 4th highest 24-hour SO₂ concentration at all stations in the period 1998–2000. In the following years this decreasing trend stopped. The slight decrease in SO₂ concentrations continued again from 2004 to 2005. In 2006 the decreasing trend stopped again and, on the contrary, SO₂ concentrations slightly increased in almost all localities of the Czech Republic. At some stations, especially in the Ústí nad Labem Region and in the Moravian-Silesian Region, more significant increase of air pollution caused by SO₂ was recorded. This increase is probably caused by the return to coal combustion in local furnaces and by unfavourable meteorological conditions in the first months of the year.
Figs. II.4.2.3 and II.4.2.4 document the courses of 1-hour and 24-hour SO₂ concentrations at the stations in 2006. Fig. II.4.2.4 confirms the increased SO₂ concentrations in winter periods of the previous years in the environs of the ZÚ station Úštěk.
Fig. II.4.2.2, presents the spatial distribution of the 4^th highest 24-hour SO₂ concentrations. On almost 7 % of the territory of the Czech Republic the SO₂ concentrations exceeded the lower assessment threshold (LAT). Only a very small area of the Czech Republic�s territory (0.01 %) recorded the exceedances of the limit value.

Tab. II.4.2.1 Stations with the highest values of the 25th and maximum hourly concentrations of SO₂

Tab. II.4.2.2 Stations with the highest numbers of exceedances of the 24-hour limit value of SO₂

Tab. II.4.2.3 Stations with the highest values of annual average concentrations of SO₂

Fig. II.4.2.1 4^th highest 24-hour concentrations and maximum hourly concentrations of SO₂ in 1996–2006 at selected stations

Fig. II.4.2.2 Field of the 4^th highest 24-hour concentration of SO₂ in 2006

Fig. II.4.2.3 Stations with the highest hourly concentrations of SO₂ in 2006

Fig. II.4.2.4 Stations with the highest 24-hour concentrations of SO₂ in 2006

II. 4.2.1.2 Suspended particles, PM₁₀ fraction and PM_2.5 fraction
The particles contained in the ambient air can be divided into primary and secondary particles. The primary particles are emitted directly into the atmosphere, both from natural and anthropogenic sources. Secondary particles1 are mostly of anthropogenic origin and are created by oxidation and consequent reactions of gaseous compounds in the atmosphere. Similarly as in the whole Europe, most emissions in the Czech Republic are of anthropogenic origin. The main anthropogenic sources include: transport, power stations, combustion sources (industrial and local), fugitive emissions from industry, loading/unloading, mining and building activities. Due to the diversity of emission sources the suspended particles have various chemical composition and various size. The PM₁₀ suspended particles have serious health impacts appearing already at low concentrations without apparent low safe concentrations threshold. Health impacts of particles are influenced by their concentration, size, shape and chemical composition. They can cause hypo-immunity, inflammation of lung tissue and oxidative stress. Increased concentrations are responsible for cardiovascular diseases and acute trombotic complications. Persistent exposure can result in respiration diseases, damaged lung function and increased mortality (lower life expectancy). Recently it has been proved that the most serious health impacts (incl. increased mortality) are recorded in PM_2.5 or PM₁ fractions which enter the lower parts of the respiratory system when inhaled.
Air pollution caused by PM₁₀, as shown in the Tables II.4.2.4. and II.4.2.5, similarly as in Fig. II.4.2.5, remains one of the main problems of air quality assurance. Fig. II.4.2.5 shows the increasing trend of PM₁₀ pollution at almost all stations in the Czech Republic from 2001 to 2003. In 2004 this trend stopped but in 2005 the PM₁₀ concentrations increased again at almost all selected stations. In 2006 this trend was confirmed at most stations only in annual averages, on the contrary, slight decrease was recorded in 24-hour concentration of PM₁₀ at most localities.
The most affected area of large coverage is, similarly as in the previous years, the Ostrava-Karviná area. In 2006 the air quality in this region was influenced by deteriorated meteorological and dispersion conditions in early January and late February, when the 24-hour PM₁₀ concentration exceeded the value of 600 μg.m^-3 at several stations (see II.4.1 Agglomerations). The limit value of 24-hour PM₁₀ concentration was exceeded in 2006, and namely at the stations in the Moravian-Silesian Region (Český Těšín, Ostrava-Bartovice, Bohumín, Ostrava-Přívoz, Karviná, Ostrava-Českobratrská (hot-spot), Věřnovice, Orlová, Havířov, Karviná ZÚ, Ostrava-Fifejdy and Ostrava-Přívoz ZÚ), at the stations in the capital city of Prague (Prague 2-Legerova (hot spot) and Prague 8-Karlín), in the Central Bohemian Region (Kladno-Švermov, Stehelčeves and Beroun), in the South Moravian Region (Brno-střed), in the Ústí nad Labem Region (Ústí n.L.-Všebořická (hot spot), Ústí n.L.-město and Teplice), in the Zlín Region (Zlín-Svit and Uherské Hradiště), in Olomouc Region (Olomouc and Olomouc-Velkomoravská. Of the total number of 148 localities in which PM₁₀ measurements were carried out, 94 stations reported exceedances of 24-hour PM₁₀ limit value. The annual PM₁₀ limit value was exceeded at 43 stations. The number of localities which exceeded the limit value in both above air pollution characteristics of PM₁₀ fraction is approximately same as in 2005.
As it is evident from Fig. II.4.2.6, in 2006 there was a certain reduction of the area with above-the-limit 24-hour concentrations of PM₁₀, especially in the whole area along the Elbe River and in the Liberec Region. Figs. II.4.2.6 and II.4.2.7 show, however, that PM₁₀ limit value exceedances are still significant for listing the basic administrative units among the areas with deteriorated air quality. Especially Fig. II.4.2.6 shows quite evidently that in the towns where the PM₁₀ measurements are carried out the 24-hour average concentrations are above the limit value. However, it can be admitted that also in the towns without PM₁₀ measurements the concentrations of this pollutant can be high or exceeding the limit value.
The map of fields of PM₁₀ concentrations (Figs. II.4.2.6 and II.4.2.7) were constructed in 2006 with the use of the empiric model which combines the dispersion model SYMOS, the European model EMEP and the altitude with the measured concentrations at rural background stations according to the methods developed within the ETC/ACC [28]. The application of the SYMOS model as the only one would not be sufficient in the case of PM₁₀ as the model calculations include only the emissions from primary sources. The significant share in PM₁₀ pollution, however, is contributed by secondary particles and re-suspended particles , which are not included in the emissions from the primary sources but considered by the EMEP model.
The result maps of PM₁₀ concentrations were created by combining the maps constructed separately for rural areas and for urban areas with the use of the population density grid.
The areas where PM₁₀ concentrations exceed the respective limit values represent, with regard to the newly constructed map, almost 28.5 % of the territory of the Czech Republic with more than 62 % of the total population.
The graphs of courses of 24-hour concentrations of PM₁₀ in 2006 at the stations, where the limit values for annual average and for 24-hour average were exceeded, are shown in Figs. II.4.2.8 and II.4.2.9. The selection of 12 localities with the greatest numbers of PM₁₀ 24-hour limit value exceedances includes 9 stations from the Moravian-Silesian Region. Fig. II.4.2.10 presents the number of exceedances of the PM₁₀ 24-hour limit value.
The complete overview of the exceedances limit value for the PM₁₀ annual average concentration for the recent 5 years is presented in Fig. II.4.2.11 and Table II.4.2.6. Fig. II.4.2.11 shows the annual average PM₁₀ concentrations for the period 2002–2006 at the localities where at least once in this period the annual limit value was exceeded. Table II.4.2.6 shows the particular values of the reached average PM₁₀ concentrations. Annual average concentrations exceeding the limit value are printed bold.
Since 2005 the fine fraction of suspended particles (PM_2.5) has been measured in the Czech Republic. In 2006 the measurements were carried out in 25 localities with valid annual average. The results show significant contribution of PM_2.5 fraction to air pollution situation in the territory of the Czech Republic. When comparing the results with the proposed annual air pollution limit value (25 μg.m^-3), it is evident that in 14 localities the limit value would be exceeded (12 in 2005). These are mainly the stations in the Ostrava-Karviná area (Věřňovice, Ostrava-Přívoz, Ostrava-Zábřeh and Ostrava-Poruba), which record the highest annual average concentrations in the Czech Republic, and in the following localities: Olomouc, Zlín, Beroun, Prague 9-Vysočany, Brno-Tuřany, Rychnov nad Kněžnou, Prague 5-Smíchov, Teplice, Kladno-střed and Most. Another 3 localities were close below the proposed limit value. The stations with the highest values of annual average concentrations of PM_2.5 are presented in Table II.4.2.7. The annual average PM_2.5 concentrations in the localities which measured this fraction in 2006 are presented in Fig. II.4.2.12 in the form of spot symbols.
For the first time this Yearbook presents the courses of daily PM_2.5 concentrations with regard to the exceedance of the proposed annual limit value of this pollutant for the year 2006 (Fig. II.4.2.14). Significant exceedance of the proposed PM_2.5 limit value was recorded in the localities of the Moravian-Silesian Region.
Fig. II.4.2.13 shows the seasonal course of the ratio between PM_2.5 and PM₁₀ fractions of suspended particles. The month average of the ratio of PM_2.5 and PM₁₀ daily concentrations averaged from 15 AIM stations and 3 manual stations with valid data for the year 2006 is presented. The measurement results indicate that the ratio between PM_2.5 and PM₁₀ is not constant but shows certain seasonal course. In 2006 the average fractions� ratio ranged between 0.67–0.83, with lower values in the summer period.
The seasonal course of PM_2.5/PM₁₀ fraction ratio is connected with the seasonal character of several emission sources. Emissions from combustion sources show higher shares of PM_2.5 fraction than for instance emissions from agriculture and reemissions during dry and windy weather. Consequently, heating in the winter period can cause the higher share of PM_2.5 fraction in comparison with PM₁₀ fraction. The decrease during the spring and early summer is also explained by the increased amount of larger biogenic particles (e.g. pollen) by some authors [29].
The lowest monitored ratio is at traffic stations. During fuel combustion the emitted particles occur mainly in PM_2.5 fraction and thus the ratio should be high in traffic localities. The fact that this is not the case, accents the significance of emissions of larger particles caused by tire, break lining and road surface abrasion.

Tab. II.4.2.4 Stations with the highest numbers of exceedances of the 24-hour limit value of PM₁₀

Tab. II.4.2.5 Stations with the highest values of annual average concentrations of PM₁₀

Tab. II.4.2.6 Overview of localities with the exceedance of the limit value for annual average PM₁₀ concentration, 2002–2006

Tab. II.4.2.7 Stations with the highest values of annual average concentrations of PM_2.5

Fig. II.4.2.5 36^th highest 24-hour concentrations and annual average concentrations of PM₁₀ in 1996–2006 at selected stations

Fig. II.4.2.6 Field of the 36^th highest 24-hour concentration of PM₁₀ in 2006

Fig. II.4.2.7 Field of annual average concentration of PM₁₀ in 2006

Fig. II.4.2.8 Stations with the highest exceedance of LV for 24-hour concentrations of PM₁₀ in 2006

Fig. II.4.2.9 Stations with the highest exceedance of LV for annual concentrations of PM₁₀ in 2006

Fig. II.4.2.10 Numbers of exceedances of air pollution limit value for the 24-hour concentration of PM₁₀ in 2006

Fig. II.4.2.11 Annual average PM₁₀ concentrations at the stations with the exceedance of the limit value, 2002–2006

Fig. II.4.2.12 Annual average concentration of PM_2.5 at stations in 2006

Fig. II.4.2.13 Average monthly PM_2.5/PM₁₀ proportions in 2006

Fig. II.4.2.14 Stations with the highest exceedance of the proposed LV for annual concentrations of PM_2.5 in 2006

II.4.2.1.3 Nitrogen dioxide

In the field of ambient air monitoring and assessment the term nitrogen oxides NO_x is used for the mixture of NO and NO₂. Air pollution limit value for the protection of human health is set for NO₂, the limit value for the protection of ecosystems and vegetation is set for NO_x.
More than 90 % of the total nitrogen oxides in the ambient air are emitted in the form of NO. NO₂ is formed relatively quickly in the reaction of NO with ground-level ozone or with HO₂ or RO₂ radicals. In a number of chemical reactions part of NO_x is transformed to HNO₃/NO₃^-, which are removed from the atmosphere through deposition (both dry and wet). NO₂ is dealt with due to its negative influence on human health. It plays also the key role in the formation of photochemical oxidants.
In Europe, NO_x emissions result mainly from anthropogenic combustion processes during which NO is formed in reaction between nitrogen and oxygen in the combusted air, and partly also by oxidation of nitrogen from the fuel. Road transport is the main anthropogenic source (significant shares however, have also air transport and water transport), and also combustion processes in stationary sources. Less than 10 % of total NO_x emissions result from combustion directly in the form of NO₂. Natural NO_x emissions result mainly from soil, volcanic activity and creation of bolts of lightning. Globally, they are important, on the European scale, however, they represent less than 10 % of total emissions. Exposure to the increased NO₂ concentrations affects lung function and can cause lower immunity.
The exceedances of annual limit values for NO₂ occur only in limited number of stations, and namely in the localities in agglomerations and large cities exposed to traffic. Of the total number of 180 localities in which NO₂ was monitored in 2006 the annual limit value was exceeded at 15 stations (Table II.4.2.9). This limit value plus the margin of tolerance (48 μg.m^-3) was exceeded at 5 localities, and namely at 3 stations in Prague (Legerova, Svornosti and Sokolovská) and at 1 station in Olomouc (Velkomoravská) and at 1 station in Brno (Svatoplukova). All the measuring sites are significantly influenced by traffic.
The AMS traffic-oriented (hot spot) Prague 2-Legerova station recorded, similarly as in the previous years, a great number of exceedances (126) of the limit value for NO₂ hourly concentration 200 μg.m^-3. In 2006, however, this AMS (as well as any other locality in the Czech Republic) did not exceed the hourly limit value plus the margin of tolerance (240 μg.m^-3). The measurement results of this station confirm again the constant big problem of the capital city of Prague with the traffic routes leading through the city centre.
At most stations presented in Fig. II.4.2.15 both the annual average concentration and the 19th highest hourly NO₂ concentration had a moderately declining trend until 2001. In 2002 this trend stopped and in 2003 there was a slight increase of NO₂ pollution at most localities. In 2004 a slight decrease was recorded but in 2005 the increasing trend of NO₂ concentrations continued again, and it was confirmed in 2006 at almost all stations. The stations Prague 2-Legerova and Pardubice-Rosice, on the contrary, show the evident decrease in absolute values of hourly concentrations of this pollutant.
The field of NO₂ annual average concentration (Fig. II.4.2.16) gives evidence of air pollution in the cities caused mainly by traffic.
Fig. II.4.2.17 presents the courses of hourly concentrations in 2006 showing the evident limit value (LV) exceedances in several localities. The exceedance of the limit value plus the margin of tolerance was not recorded, the highest number of exceedances of the value 200+40 μg.m^-3 was recorded at the AMS Prague 2-Legerova (hot spot, 8x) monitoring the traffic load; the admissible exceedance frequency is 18.
When constructing the map in Fig. II.4.2.16 also national traffic census from the year 2005 was regarded. As compared with the previous census in 2000, i.e. during the recent 5 years, the increase of traffic is significant. The higher NO₂ concentrations can occur also in the vicinity of local communications in the villages with intensive traffic and dense local transport network.

Tab. II.4.2.8 Stations with the highest values of the 19^th and maximum hourly concentrations of NO₂

Tab. II.4.2.9 Stations with the highest values of annual average concentrations of NO₂

Fig. II.4.2.15 19^th highest hourly concentrations and annual average concentrations of NO₂ in 1996–2006 at selected stations

Fig. II.4.2.16 Field of annual average concentration of NO₂ in 2006

Fig. II.4.2.17 Stations with the highest hourly concentrations of NO₂ in 2006

Fig. II.4.2.18 Stations with the highest exceedance of LV and LV+MT for annual concentrations of NO₂ in 2006

II. 4.2.1.4 Carbon monoxide

The insufficient burning of fossil fuels may be an anthropogenic source of air pollution caused by carbon monoxide. These processes occur mainly in transport and in stationary sources, namely household heating.
Carbon monoxide can cause headache, deteriorated coordination and attention. It binds to haemoglobin and the increased concentrations of the created carboxyhaemoglobin reduce the capacity of blood for the oxygen transport.
In 2006 carbon monoxide concentrations were measured at 43 localities. Maximum daily 8-hour running averages of carbon monoxide do not exceed the limit value (10 mg.m^-3) at any of the stations. The highest daily 8-hour average concentration was measured at the hot spot locality Ostrava-Českobratrská (5.8 mg.m^-3).
The courses of maximum daily 8-hour running averages for selected localities are presented in Fig. II.4.2.20. The air pollution situation caused by carbon monoxide in 2006 is characterized in Table II.4.2.10.

Tab. II.4.2.10 Stations with the highest values of maximum 8-hour running average concentrations of CO

Fig. II.4.2.19 Maximum 8-hour running average concentrations of CO in 1996–2006 at selected stations

Fig. II.4.2.20 Stations with the highest values of maximum 8-hour running average concentrations of CO in 2006

II.4.2.1.5 Benzene

With the increasing intensity of road transport the monitoring of air pollution caused by aromatic hydrocarbons is becoming relevant. The decisive source of atmospheric emissions of aromatic hydrocarbons – and namely of benzene and its alkyl derivates – are above all exhaust gases of petrol motor vehicles. Another source are loss evaporative emissions produced during petrol handling, storing and distribution. Mobile sources emissions account for approx. 85 % of total aromatic hydrocarbons emissions, while the prevailing share is represented by exhaust emissions. It is estimated that the remaining 15 % of emissions come from stationary sources. Many of these are related to industries producing aromatic hydrocarbons and those industries that use these compounds to produce other chemicals.
The research shows that benzene level in petrol is about 1.5 % while diesel fuels contain relatively insignificant benzene concentrations. Exhaust benzene is produced primarily by unburned benzene from fuels. Non-benzene aromatics in the fuels can cause 70 to 80 % of the exhaust benzene formed. Some benzene also forms from engine combustion of non-aromatic fuel hydrocarbons. The most significant adverse effects from exposure to benzene are haematotoxicity and carcinogenicity [16].
The situation of the year 2006 is characterized in Table II.4.2.11 and Fig. II.4.2.22. Of the total number of 31 localities monitoring benzene concentrations in 2006 the limit value 5 μg.m^-3 plus the margin of tolerance (in 2006 4 μg.m^-3) was exceeded, similarly as in the previous year, in the ZÚ locality Ostrava-Přívoz (12.1 μg.m^-3) and in the CHMI locality Ostrava-Přívoz (11.5 μg.m^-3). Close below the limit value remained the locality Ostrava-Fifejdy with the annual average 4.9 μg.m^-3). Higher concentrations are connected with industrial activities in this area (mainly coke production).
The air pollution limit value 5 μg.m^-3 must be met by 31.12.2009.
The annual average benzene concentrations slightly increased at most localities as compared with the previous year.
The map diagram (Fig. II.4.2.21) shows the overview of the development of average annual concentrations in 1999–2006. Fig. II.4.2.23 presents the annual course of 24-hour averages in selected localities.

Tab. II.4.2.11 Stations with the highest values of annual average concentrations of benzene

Fig. II.4.2.21 Annual average concentrations of benzene in 1999–2006 at selected stations

 Fig. II.4.2.22 Field of annual average concentration of benzene in the ambient air in 2006

Fig. II.4.2.23 24-hour concentrations at the stations with the highest annual benzene concentrations in 2006

II.4.2.1.6 Ground-level ozone

Ground-level ozone is a secondary pollutant in the ambient air with no significant emission source of its own. It is formed under the influence of solar radiation during complex photochemical reactions mainly between nitrogen oxides, VOC  (mainly hydrocarbons) and other components of the atmosphere. Ozone is a very powerful oxidizing agent. Ozone impairs mainly the respiratory system and irritates mucous membranes. It causes morphological, biochemical and functional changes and impairs the immune system response. There is evidence for ozone toxicity to vegetation.
The Government Order No. 597/2006 Coll. requires to assess the ozone concentrations in relation to human health protection as an average for the latest three years. If the latest three years are not available, the average for the latest two years or one year is taken into account pursuant to the Government Order. In 2006 ozone was measured at 73 localities out of which 39 (53 %) exceeded the target value for the three-year period 2004–2006, or shorter (see Table II.4.2.12). According to this assessment the maximum number of exceedances was recorded at the locality Churáňov, where the average number of exceedances of the maximum daily 8-hour running average 120 μg.m^-3 reached the value of 69.3. In comparison with the previous three-year period 2003–2005 there was a slight decrease of the relative number of stations with target value exceedances. The map with the 26th highest maximum daily 8-hour running averages shows clearly the slight reduction of the territory with concentrations above 120 μg.m^-3. More than 75 % of stations recorded the decline of the average number of exceedances above 120 μg.m^-3 in the average for the period 2004–2006 as compared with the average for the period 2003–2005. In 2003–2005 the above-the-limit concentrations of ground-level ozone occurred in 99 % of the territory of the Czech Republic, in 2004–2006 in 88 %. This was caused by the fact that the assessment of the latest three-year period (2004–2006) did not include the year 2003 when there were recorded long-lasting high temperatures and high values of sun radiation, and the ground-level ozone concentrations reached extremely high values. The year 2006 was also warm (as compared to the two previous years), however, its average temperature for the months April–September, during which ozone concentrations have usually the highest values, was by 0.7� C lower than in 2003; ozone concentrations were relatively high.
The ground-level ozone concentrations generally grow with the increasing altitude which is confirmed also by the data measured for the year 2006 when the localities with highest loads (see Table II.4.2.12) are situated at higher altitudes. The traffic localities in the cities are the least loaded ones as ozone is degraded there through chemical reaction with NO. It can be expected that the ozone concentrations are below the target value also in other cities with heavier traffic. However, due to the absence of measurements the probable decrease cannot be documented by the use of current methods of map construction.
Map diagram in Fig. II.4.2.24 shows the 26th highest value of maximum 8-hour running average of ozone concentrations (three-year average) in 1996–2006.
Table II.4.2.12 presents the stations with the highest values of maximum daily 8-hour running average ozone concentrations in three-year average. Fig. II.4.2.26 shows the graph of the number of exceedances of the target value for ground-level ozone and Fig. II.4.2.27 presents the annual courses of maximum daily 8-hour running averages in the localities with the heaviest loads.
Table II.4.2.13 presents the number of hours of the ozone alert threshold exceedance (180 μg.m^-3) at selected AIM stations for the whole period of 1992–2006.

Tab. II.4.2.12 Stations with the highest values of maximum daily 8-hour running average concentrations of ozone

Tab. II.4.2.13 Number of hours of the ozone alert threshold exceedance (180 μg.m^-3) per year at selected AIM stations, 1992–2006

Fig. II.4.2.24 26th highest values of maximum 8-hour running average of ground-level ozone concentrations (three-year average) in 1996–2006 at selected stations

Fig. II.4.2.25 Field of the 26th highest maximum daily 8-hour running average of ground-level ozone concentration in three-year average, 2004–2006

Fig. II.4.2.26 Numbers of exceedances of the target value for the maximum daily 8-hour running average of ground-level ozone concentrations in three-year average, 2004–2006

Fig. II.4.2.27 Stations with the highest values of maximum daily 8-hour running average concentrations of ground-level ozone in 2004–2006

II.4.2.1.7 Heavy metals

Lead
Most lead contained in the atmosphere result from anthropogenic emissions caused by high-temperature processes, primarily the burning of fossil fuels, production of iron and steel and metallurgy of non-ferrous metals. Means of transport using leaded petrol represent a very significant source of anthropogenic emissions. In the natural processes lead is released through the weathering of rocks and volcanic activity [14].
Airborne lead occurs in the form of fine particles with frequency particle size distribution characterized by the average aerodynamic diameter lower than 1 μm.
The long-term exposure to lead results in harmful impacts on biosynthesis of haem (nonproteinic component of haemoglobin), on nervous system and blood pressure in humans. The evidence for carcinogenic potential of lead and its compounds in humans is inadequate [14, 15].
None of the 70 localities recorded the exceedance of the limit value (500 ng.m^-3). In 2006 the highest concentration was reached in the ZÚ locality Ostrava-Bartovice (120.8 ng.m^-3). Lead concentrations in all localities remained far below the limit value and did not even reach the lower assessment threshold (see Fig. II.4.2.28). Courses of short-term average concentrations (24-hour or14-day concentrations, depending on the measurement schedule of the given station) at selected stations are presented in Fig. II.4.2.29.
The stations with the highest values of annual average concentrations are presented in Table II.4.2.14.

Tab. II.4.2.14 Stations with the highest values of annual average concentrations of lead in the ambient air

Fig. II.4.2.28 Annual average concentrations of lead in the ambient air in 1996–2006 at selected stations

Fig. II.4.2.29 1/14-day average concentrations of lead in the ambient air at selected stations in 2006

Cadmium
Globally, the anthropogenic sources of cadmium emission in the ambient air represent about 90 % (mainly iron and steel production, metallurgy of non-ferrous metals, refuse incineration and fossil fuels combustion (brown coal, hard coal and heavy fuel oils) [17]. Emissions from transport are less significant. The remaining 10 % represent natural sources (mainly caused by volcanic activity).
Cadmium is bound mainly to the fine particles (aerodynamic diameter up to 2.5 μm), with higher risk of negative effects on human health. Almost all cadmium is bound to particles up to 10 μm, while the minimum amount of cadmium is found in particles with diameter above 10 μm.
The kidney is the critical organ with respect to long-term exposure to cadmium. Its carcinogenic effects are evident in experimental animals and there has been limited evidence in humans so far [15, 17].
In 2006 cadmium was measured at 69 localities which submitted sufficient data for the calculation of the valid annual average.
The target value (5 ng.m^-3) was not exceeded. In the locality Tanvald, where target value was exceeded repeatedly in the previous years, the necessary number of valid data for the calculation of the annual average was not reached. Nevertheless in 3 of 4 months for which the monthly average is available, the target value was exceeded. In February, the monthly average was more than double than the target value and in November even more than 3x higher than the target value. It can be supposed with high probability that if the Tanvald station�s measurement results were usable for the assessment, the target value would be exceeded again. In 2005 the maximum average annual concentrations were measured in the Liberec Region (localities Tanvald, Souš, Liberec-Vratislavice), in 2006 the maximum average concentrations were measured in two localities with heavy loads in Ostrava (Ostrava-Bartovice, Ostrava-Mariánské Hory) which started to submit the measured data to the ISKO database on 1.1.2006. The target value for cadmium must be met by 31.12.2012.
The development of annual average concentrations in the period of 1996–2006 is apparent from Fig. II.4.2.30.
The courses of short-term (24-hour, or 14-day concentrations, according to the measurement schedule at the respective station) average cadmium concentrations in selected localities in 2006 are presented in Fig. II.4.2.32.
The stations with the highest values of annual average concentrations are presented in Table II.4.2.15.

Tab. II.4.2.15 Stations with the highest values of annual average concentrations of cadmium in the ambient air

Fig. II.4.2.30 Annual average concentrations of cadmium in the ambient air in 1996–2006 at selected stations

Fig. II.4.2.31 Field of annual average concentration of cadmium in the ambient air in 2006

Fig. II.4.2.32 1/14-day average concentrations of cadmium in the ambient air at selected stations in 2006

Arsenic
Arsenic occurs in many forms of inorganic and organic compounds. Anthropogenic sources represent about three quarters of total emissions in the ambient air. Significant amounts are contributed mainly from combustion processes (brown coal, hard coal and heavy fuel oils), iron and steel industry and production of copper and zinc. Main natural sources of arsenic include mainly volcanic activity, wildfires, weathering of minerals and activity of microorganisms (in wetlands, swamps and circumlittoral areas) [17].
Arsenic occurs largely in fine fractions (aerodynamic diameter up to 2.5 μm), which can be transported over long distances and can penetrate deeply into the respiratory system. Almost all arsenic is bound to particles with aerodynamic diameter up to 10 μm [17].
Inorganic arsenic can cause acute, subacute or chronic effects (local or affecting the whole organism). Lung cancer can be considered the critical effect following inhalation exposure [15, 17].
Of the total number of 67 localities which submitted sufficient data for the calculation of the valid annual average for 2006 the target value 6 ng.m^-3 was exceeded in 3 localities (Ostrava-Bartovice [13.5 ng.m^-3], Ostrava-Mariánské Hory [8.6 ng.m^-3] a Kladno-Švermov [6.4 ng.m^-3]). In previous years data from these stations were not available. In the locality Tanvald, where the target value was exceeded repeatedly in the previous years, the necessary number of valid data for the calculation of annual average was not reached. Nevertheless in 2 of 4 months, from which the monthly average is available, the target value was exceeded. The target value for arsenic must be met by 31.12.2012.
The map for arsenic shows an apparent slight deterioration of air pollution situation (Prague, Central Bohemian Region, Ústí nad Labem Region). More significant deterioration in the Moravian-Silesian Region can be explained by a slight increase of concentrations in current localities and by the assessment of the results of new measurements in areas with heavy loads (localities Ostrava-Bartovice, Ostrava-Mariánské Hory).
The development of annual average concentrations during the years 1996–2006 is apparent from Fig. II.4.2.33.
The courses of short-term (24-hour, or 14-day concentrations, according to the measurement schedule at the respective station) average arsenic concentrations show the seasonal character of the short-time arsenic concentrations in the ambient air and confirm the significant arsenic contribution from the burning of fossil fuels (Fig. II.4.2.35).
The stations with the highest annual average concentrations are presented in Table II.4.2.16.

Tab. II.4.2.16 Stations with the highest values of annual average concentrations of arsenic in the ambient air

Fig. II.4.2.33 Annual average concentrations of arsenic in the ambient air in 1996–2006 at selected stations

Fig. II.4.2.34 Field of annual average concentration of arsenic in the ambient air in 2006

Fig. II.4.2.35 1/14-day average concentrations of arsenic in the ambient air at selected stations in 2006

Nickel
Nickel is the fifth most abundant element of the earth core, though in the earth crust its percentage share is lower.
The main anthropogenic sources, which globally represent about three quarters of total emissions, include combustion of heavy fuel oils, mining of nickel-containing ores and nickel refinement, waste incineration and iron and steel production. Main natural sources include continental dust and volcanic activity.
Nickel occurs in the atmospheric aerosol in several chemical compounds which differ by its toxicity for human health and ecosystems.
About 70 % of particles containing nickel comprise the fraction smaller than 10 μm. These particles can be transported over long distances. About 30 % of particles containing nickel have aerodynamic diameter equal or higher than 10 μm and quickly settle in the vicinity of the source [17].
The health effects include allergic dermatitis and there is evidence of nickel carcinogenicity for humans [15, 17].
None of the total 63 localities from which sufficient data for the calculation of the valid annual average for 2006 were obtained, similarly as in previous years, exceeded the set target value. Nevertheless, in comparison with the previous year 2005, the maximum annual averages slightly increased. The highest valid annual average concentration was measured in the locality Ostrava-Mariánské Hory (annual concentration 10.3 ng.m^-3). This was the one and only case of the lower assessment threshold exceedance. The stations with the highest values of the annual average concentrations are presented in Table II.4.2.17.
The annual course of short-term (24-hour, or 14-day) nickel concentrations is apparent from Fig. II.4.2.37.

Tab. II.4.2.17 Stations with the highest values of annual average concentrations of nickel in the ambient air

Fig. II.4.2.36 Annual average concentrations of nickel in the ambient air in 1996–2006 at selected stations

Fig. II.4.2.37 1/14-day average concentrations of nickel in the ambient air at selected stations in 2006

II.4.2.1.8 Benzo(a)pyrene
The cause of the presence of benzo(a)pyrene, the main representative of polycyclic aromatic hydrocarbons (PAH) in the ambient air is, similarly as in other PAH, the insufficient burning of fossil fuels both in stationary and mobile sources, and also some technologies, as coke and iron production. Stationary sources are represented mainly by local heating (coal combustion). Mobile sources are represented mainly by diesel motors. The natural background level of benzo(a)pyrene is almost zero with the exception of wildfires [15].
Approximately 80–100 % of PAH with 5 and more aromatic cores (i.e. also benzo(a)pyrene) are bound mainly to the particles smaller than 2.5 μm, i.e. to the so called fine fraction of atmospheric aerosol PM_2.5 (sorption on the surface of the particles). These particles remain in the atmosphere for relatively long time (days to weeks) which enables their transport over long distances (hundreds to thousands of kilometers).
Benzo(a)pyrene, as well as several other PAH, are classified as proven human carcinogens [15, 19].
In 2006 benzo(a)pyrene was monitored in 28 localities, out of which 24 (86 %) exceeded the target value of 1 ng.m^-3 (in 2005 – 85 % of localities, in 2004 – 56 %, in 2003 – 66 %). All localities classified as urban or suburban recorded the exceedance of the target value, with the exception of two stations at which the annual average was equal to the target value. Only two rural stations recorded the annual average concentrations below the target value. This fact confirmed the suspicion that the target value is exceeded, due to local sources, also in villages and towns where there is no measurement and which were not included in air pollution maps in the previous years.
Therefore in 2006 the mapping methods used for the assessment of air pollution caused by benzo(a)pyrene were markedly improved. Based on the results of measurements and modelling, the maps for urban and rural areas were created separately, and then merged into one final map. In addition to the stationary sources the map regards also traffic emissions, and namely benzo(a)pyrene emissions from highways and primary roads. It is supposed that the share of benzo(a)pyrene emissions to total PAH emissions is about 4 %. The map was created also with regard to the gradient of benzo(a)pyrene air pollution concentrations with the altitude. Consequently, a number of towns and villages ended up in the areas with exceeded target value (total 9 % of the territory of the Czech Republic, in 2005 – only 5.2 %), with about 69 % of the population (in 2005 – 39 % of the population).
However, it is necessary to consider that the estimates of the fields of annual average benzo(a)pyrene concentrations, in comparison with other mapped pollutants, bear the greatest uncertainties which result both from insufficient measurement density and from uncertainties given by dispersion modelling of PAH emissions; PAH emission inventories represent the largest source of uncertainties.
The concentration measured in Ostrava-Bartovice (11.7 ng.m^-3) was by far the highest. The level of the target value was exceeded almost 12x.
The target value for benzo(a)pyrene must be met by 31.12.2012.
The development of annual average concentrations in individual localities during 1997–2006 is apparent from Fig. II.4.2.38. The annual course of short-term concentrations (24-hour once in 3 or 6 days) of benzo(a)pyrene is presented in Fig. II.4.2.41. The fluctuations of monthly averages of concentrations for different types of stations in 2004–2006 are shown in Fig. II.4.2.40. The increase of concentrations during the winter periods confirm the influence of local furnaces.

Tab. II.4.2.18 Stations with the highest values of annual average concentrations of benzo(a)pyrene in the ambient air

Fig. II.4.2.38 Annual average concentrations of benzo(a)pyrene in 1997–2006 at selected stations

Fig. II.4.2.39 Field of annual average concentration of benzo(a)pyrene in the ambient air in 2006

Fig. II.4.2.40 Month average concentrations of benzo(a)pyrene at various types of localities, 2004–2006

Fig. II.4.2.41 24-hour concentrations at the stations with the highest annual concentrations of benzo(a)pyrene in 2006

II.4.2.1.9 Other substances

Mercury
Main anthropogenic sources of mercury include combustion of fossil fuels, chlor-alkali production, metallurgy, cement production and refuse incineration. Mercury and its compounds are used in paint industry, battery production, measuring and control instruments (thermometers) [18].
The natural sources (representing about 60 % of total emissions) include mainly mercury evasion from aquatic ecosystems and vegetation, volcanic activity and de-gassing from mercury-rich minerals. As for anthropogenic emissions it is estimated that in Europe approximately 60 % of mercury is emitted in the form of elemental vapour Hg0, 30 % as divalent mercury (Hg (II)), and only 10 % as particulate phase mercury (H(p)). Most emissions from natural sources are in gaseous form Hg0 [18].
Studies of occupationally exposed humans have shown adverse effects on the central nervous system and kidneys at high mercury vapour levels [18]. The increased concentrations in the ambient air result in higher atmospheric deposition on top water layers and, consequently, in higher methylmercury concentrations in freshwater fish and its accumulation in food chains. [15, 18].
In spite of the fact that the limit value for mercury has not been set yet, the Czech national legislation recommends, pursuant to the European directives, to carry out its monitoring and assessment according to the annual arithmetic mean. In 2006 the CHMI ISKO database received data on mercury concentrations from 6 localities in total: from the CHMI locality Ústí nad Labem-město, from the locality Karviná ZÚ and from 4 ZÚ localities in Ostrava. Only 2 localities reached the sufficient number of data for the calculation of the valid annual average, and namely the locality Ostrava-Mariánské Hory (annual average 0.8 ng.m^-3) and Ostrava-Bartovice (annual average 1.2 ng.m^-3).
Table II.4.2.19 presents the overview of the stations measuring mercury in the ambient air and the annual average and maximum 24-hour concentrations.

Tab. II.4.2.19 Stations measuring mercury in the ambient air with the values of annual average and maximum 24-hour concentrations

Ammonia
Major part of ammonia emitted in the ambient air is created by disintegration of nitrogenous organic materials from domestic animals breeding. The remaining amount is emitted through combustion processes or production of fertilizers. It is apparent that ammonia emissions in the ambient air are contributed by vehicles (formation of ammonia in catalytic convertors). Ammonia has irritating effects on eyes, skin and respiratory system. Chronic exposure to increased concentrations can cause headache and vomiting [20]. Quite significant are ammonia odour annoyance impacts on the population.
Similarly as in the case of mercury, the limit value for ammonia is not defined in the current European and Czech legislation. Ammonia monitoring was carried out at 4 localities in 2006. The highest annual average concentration was measured at the station Lovosice-MÚ (11.1 μg.m^-3).
Table II.4.2.20 presents the overview of stations measuring ammonia in the ambient air and annual average and maximum 24-hour concentrations.

Tab. II.4.2.20 Stations measuring ammonia in the ambient air with the values of annual average and maximum 24-hour concentrations

II.4.2.1.10 Trends of annual air pollution characteristics of SO₂, PM₁₀, NO₂, NO_x and O₃ for the period 1996–2006

The result concentrations of pollutants in the Czech Republic and agglomerations, related to the respective years, represent average values from the stations which measured for the whole monitored period.
Fig. II.4.2.42 shows the trends of SO₂, PM₁₀, NO₂, NO_x and O₃ annual air pollution characteristics in the Czech Republic for the period of 1996–2006. Up to the year 2000 air pollution caused by SO₂, PM₁₀, NO₂ and NO_x had a decreasing trend in the whole Czech Republic. In SO₂ and PM₁₀ concentrations the decline was very steep up to the year 1999. In 2001 the decreasing trend was interrupted in the whole Czech Republic and, on the contrary, a slight increase of SO₂, NO₂ and NO_x concentrations and a significant increase of PM₁₀ concentrations occurred. In 2004 this increasing trend of air pollution caused by PM₁₀, NO₂ and NO_x finished and, on the contrary, certain decrease of these pollutants� concentrations occurred, reaching almost the levels of the year 2001. In 2005 the PM₁₀ and NO₂ concentrations returned back to the increasing trend, in PM₁₀ the increase was steeper, beyond the level of the year 2002. This increasing trend was confirmed in 2006 in NO₂ and in annual PM₁₀ concentrations (at urban stations); more significant increase was recorded in case of one-hour NO₂ concentrations – it almost reached the level of the year 1997. On the contrary, 24-hour PM₁₀ concentrations recorded a slight decrease. Between 2003 and 2005 a slight decrease of SO₂ concentrations was observed. In 2006 this trend stopped and, on the contrary, a slight increase of SO₂ concentrations was recorded in all air pollution characteristics.
In O₃ there is an apparent decreasing trend up to 1997. In 1998–2002 the O₃ concentrations stagnated. In 2003 there is apparent the increasing trend in concentrations due to long lasting very high temperatures and high levels of solar radiation. In 2004 O₃ concentrations slightly decreased below the level from the years 1997–2002, in 2005 they amounted slightly above the level from 1997–2002. In 2006 the concentrations increased again. The year 2006 was the year with the second highest ozone concentrations (the average of the 26th highest values of maximum 8-hour running averages from all stations) within the period 1996–2006, next to the extreme recorded in 2003. The graphs of trends show apparent higher concentrations at rural localities as compared with the concentrations from urban and suburban localities, where ozone is removed mainly by emissions from traffic.

Fig. II.4.2.42 Trends of SO₂, PM₁₀, NO₂, NO_x and O₃ annual characteristics in the Czech Republic, 1996–2006