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AIR POLLUTION IN THE CZECH REPUBLIC IN 2007 Czech Hydrometeorological Institute - Air Quality Protection Division |
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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
In 2007 the set limit value for 24-hour SO2 concentration (125 μg.m-3,
tolerated number of exceedances – 3) was exceeded only in the locality Litvínov
(ZÚ). The exceedance of the value 125 μg.m-3 (in the tolerated
number) was recorded also in other localities of the Ústí nad Labem Region. 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 of the value 350 μg.m-3 was recorded at the AMS station
Teplice – 18). 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 2007. Fig. II.4.2.4 confirms the increased SO2 concentrations in winter periods in the environs of the ZÚ station Litvínov. Fig. II.4.2.2 presents the spatial distribution of the 4th highest 24-hour SO2 concentration. On only 1.6 % of the territory of the Czech Republic the SO2 concentrations exceeded the lower assessment threshold (LAT). Tab. II.4.2.1 Stations with the highest values of the 25th and maximum hourly
concentrations of SO2
Fig. II.4.2.1 4th highest 24-hour concentrations and maximum hourly
concentrations of SO2 in 1996–2007 at selected stations II. 4.2.1.2 Suspended particles, PM10 fraction and PM2.5
fraction Air pollution caused by PM10, remains one of the main problems of air quality assurance. This situation is confirmed by Tables II.4.2.4 and II.4.2.5, similarly as by Fig. II.4.2.5 showing the obviously 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 continued at most stations in annual averages. In 2007 the decrease of PM10 concentrations was recorded. The most affected area of large coverage is, similarly as in the previous years, the Ostrava-Karviná area. The limit value of 24-hour PM10 concentration was exceeded in 2007, and namely at the stations in the Moravian-Silesian Region (Ostrava-Bartovice, Bohumín, Český Těšín, Ostrava-Přívoz, Věřnovice, Karviná, Ostrava-Českobratrská (hot spot), Havířov, Orlová, Ostrava-Fifejdy, Ostrava-Přívoz ZÚ, Ostrava-Mariánské Hory, Karviná ZÚ and Ostrava-Zábřeh), at the stations in the capital city of Prague (Prague 2-Legerova (hot spot), Prague 8-Karlín and Prague 5-Smíchov), in the Zlín Region (Zlín-Svit and Uherské Hradiště), in the Vysočina Region (Jihlava-Znojemská), in the Central Bohemian Region (Kladno-Švermov, Stehelčeves and Beroun), in the South Moravian Region (Brno-střed and Brno-Masná), in the Ústí nad Labem Region (Ústí n.L.-Všebořická (hot spot), Most, Lom and Ústí n.L.-město). Of the total number of 155 localities in which PM10 measurements were carried out, 54 stations reported exceedances of 24-hour PM10 limit value. The annual PM10 limit value was exceeded at 16 stations. The number of localities which exceeded the limit value in both above air pollution characteristics of PM10 fraction significantly decreased in 2007 as compared with 2006. This decrease was influenced by more favourable meteorological and dispersion conditions, mainly in January and February 2007. The decrease of PM10 concentrations is more obvious at urban and suburban stations than at traffic and industrial ones, unlike the previous year. As it is evident from Fig. II.4.2.6, in 2007 there was a reduction of the area
with above-the-limit 24-hour concentrations of PM10, especially in
the Ústí nad Labem, Central Bohemian, Hradec Králové, Pardubice, Olomouc and
South Moravian regions. 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 spatial projections of PM10 concentrations show,
that in 2007 the respective limit values for PM10 were exceeded on
6.3 % of the territory of the Czech Republic with approx. 32 % of inhabitants. The complete overview of the exceedances of the 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 2003–2007 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 (PM2.5) has been measured in the Czech Republic. In 2007 the measurements were carried out in 32 localities which fulfilled the requirement for the minimum number of measured data for the assessment. The measurement results show significant contribution of PM2.5 fraction to air pollution situation in the part of the territory of the Moravian-Silesian Region. When comparing the results with the target annual limit value pursuant to the Directive 2008//EC of the European Parliament and of the Council (25 μg.m-3), it is evident that in 5 localities the target limit value was exceeded (14 in 2006). These are the stations in the Ostrava-Karviná area (Bohumín, Věřňovice, Ostrava-Přívoz, Ostrava-Zábřeh and Třinec-Kosmos). Annual average concentrations in two other localities were close below the target limit value. The stations with the highest values of annual average concentrations of PM2.5 are presented in Table II.4.2.7. The annual average PM2.5 concentrations in the localities which measured this fraction in 2007 are presented in Fig. II.4.2.12 in the form of spot symbols. Fig. II.4.2.14 shows the courses of daily PM2.5 concentrations with regard to the exceedance of the target annual limit value of this pollutant pursuant to the Directive 2008/50/EC. The exceedance of this PM2.5 limit value was recorded only in the localities of the Moravian-Silesian Region. Fig. II.4.2.13 shows the seasonal course of the ratio between PM2.5 and PM10 fractions. It is the month average of the ratio of PM2.5 and PM10 daily concentrations from the stations which had sufficient valid data for the year 2007. The measurement results indicate that the ratio between PM2.5 and PM10 is not constant but shows certain seasonal course and, simultaneously, it is dependent on the locality classification and position. In 2007 the ratio, in the average from all 25 stations in the Czech Republic (simultaneously measuring PM2.5 and PM10) ranged from 0.66 (May, July) to 0.75 (February) with lower values in the summer period. In Prague (3 stations) this ratio was from 0.52 (May) to 0.69 (February), in the Ústí nad Labem Region (4 stations) 0.56 (May) to 0.68 (February) and in the Moravian-Silesian Region (5 stations) 0.70 (May) to 0.86 (December). When comparing the ratio with regard to the classification of stations, the ratio in urban stations (6 stations) is 0.65 (July) to 0.77 (February), in suburban stations (5 stations) 0.64 (September) to 0.77 (December) and traffic stations (4 stations) 0.60 (September) to 0.69 (February). It should be taken into account that the number of stations with simultaneous measurement of PM2.5 and PM10 is not sufficient enough. The seasonal course of PM2.5/PM10 fraction ratio is connected with the seasonal character of several emission sources. Emissions from combustion sources show higher shares of PM2.5 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 PM2.5 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 PM2.5 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. PM10 annual concentrations without the influence of meteorological
conditions Daily averages of individual stations were used for the calculation of the averages for the territory of Prague. These averages were divided into two categories: days with good dispersion conditions, or good for the part of the day and slightly unfavourable for the other; the second category contained the days with slightly unfavourable or unfavourable dispersion conditions. The values classified as above were used for the determination of the averages for individual years. This procedure enables the monitoring of the trends of development of the level of PM10 air pollution concentrations, without the influence of meteorological conditions. Fig. II.4.2.15 shows clearly that air pollution load of PM10 suspended particles in the territory of Prague between 2000 and 2003 increased, independently of the meteorological conditions. After 2003 a marked decrease of air pollution loads occurred in the territory of Prague. This trend is observed for both categories of dispersion conditions, and thus it is apparent, that this decrease is not caused by the differences in weather conditions in individual years. The declining trend of PM10 concentrations was to a certain extent interrupted in 2006. However, it was significant only in the category of unfavourable dispersion conditions, and thus it is obvious that it was caused by great occurrence of inversion situations in 2006. Consequently, it can be expected that this trend of annual PM10 concentrations is similar on the most of the territory of the Czech Republic. The March 2007 episode of high PM10 concentrations All automated monitoring stations (AMS) in the Czech Republic recorded gradual increase of hourly PM10 concentrations from the east, over 800 μg.m-3 in the eastern part up to 400 μg.m-3 in the western part of the territory of the Czech Republic (Figs. II.4.2.16 and II.4.2.17).
Tab. II.4.2.4 Stations with the highest numbers of
exceedances of the 24-hour limit value of PM10
Fig. II.4.2.5 36th highest 24-hour concentrations and annual average
concentrations of PM10 in 1996–2007 at selected stations
II.4.2.1.3 Nitrogen dioxide 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 NOx 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, NOx 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 NOx emissions result from combustion directly in the form of NO2. Natural NOx 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 182 localities in which NO2 was monitored in 2007 the annual limit value was exceeded at 17 stations (Table II.4.2.9). This limit value plus the margin of tolerance (46 μg.m-3) was exceeded at 6 localities, and namely at 5 stations in Prague (Svornosti, Legerova, Sokolovská, Národní muzeum and Jasmínová) and at 1 station in Brno (Svatoplukova). All the measuring sites are significantly influenced by traffic. It can be expected that the exceedances of the limit values can occur also at other localities exposed to traffic, where there is no measurement. The AMS traffic-oriented (hot spot) Prague 2-Legerova station recorded, similarly as in the previous years, a great number of exceedances (254) of the limit value for NO2 hourly concentration 200 μg.m-3. In 2007 this AMS exceeded also the hourly limit value plus the margin of tolerance 230 μg.m-3 (83x). 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.4.2.18 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. In 2007 a marked decrease of NO2 concentrations was recorded at the stations due to more favourable meteorological and dispersion conditions. The field of NO2 annual average concentration (Fig. II.4.2.19) gives evidence of air pollution in the cities caused mainly by traffic. Figs. II.4.2.20 and II.4.2.21 show the graphs of the courses of daily and hourly concentrations in 2007 showing the evident limit value (LV) exceedances in localities. Of the six localities which exceeded the annual limit value plus the margin of tolerance 5 stations are located in Prague. The exceedance of the hourly limit value plus the margin of tolerance (200+30 μg.m-3) was recorded at the AMS Prague 2-Legerova (hot spot, 83x) monitoring the traffic load; the admissible exceedance frequency is 18. When constructing the map in Fig. II.4.2.19 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 19th and maximum hourly concentrations of NO2
Fig. II.4.2.18 19th highest hourly concentrations and annual average
concentrations of NO2 in 1996–2007 at selected stations II. 4.2.1.4 Carbon monoxide In 2007 carbon monoxide concentrations were measured at 45 localities. Maximum daily 8-hour running averages of carbon monoxide did not exceed the limit value (10 mg.m-3) at any of the stations. The highest daily 8-hour average concentration was measured, similarly as in the previous year, at the hot spot locality Ostrava-Českobratrská (4.6 mg.m-3). However, the lower assessment threshold was not exceeded there in 2007. The courses of maximum daily 8-hour running averages for selected localities are presented in Fig. II.4.2.23. The air pollution situation caused by carbon monoxide in 2007 is characterized in Table II.4.2.10. Fig. II.4.2.22 Maximum 8-hour running average concentrations of CO in
1996–2007 at selected stations II.4.2.1.5 Benzene 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]. In 2007 benzene concentrations were measured in 33 localities in total. The
limit value is defined as an annual average concentration 5 μg.m-3.
This limit must be achieved by 31.12.2009. The margin of tolerance for the year
2007 reached the value of 3 μg.m-3. The annual average concentration
measured at the CHMI station Ostrava-Přívoz amounted to this exact value 8 μg.m-3
(5 + 3 μg.m-3). The limit value was further exceeded at the ZÚ
station Ostrava-Přívoz (annual average 5.9 μg.m-3). Higher
concentrations in this area are connected with industrial activities (mainly
with coke production). In 2006 both localities recorded the exceedance of the
limit value + the margin of tolerance. During the recent 3 years the lowest
concentrations in these localities were measured in 2007. As compared with the
year 2006, the concentrations decreased at all stations. The increase measured
at all stations in 2006 was thus not confirmed. The situation was rather similar
to that in the year 2005, as the number of stations with a slight increase of
annual average concentrations was roughly equal to the number of stations with a
slight decrease of the concentrations. Tab. II.4.2.11 Stations with the highest values of annual average concentrations of benzene Fig. II.4.2.24 Annual average concentrations of benzene in 1998–2007 at
selected stations
tional 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 2007 ozone was measured at 72 localities out of which 47 (65.3 %) exceeded the target value for the three-year period 2005–2007, or shorter (see Table II.4.2.12). According to this assessment the maximum number of exceedances was recorded, similarly as in the previous year, 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 73.7. The comparison of the three assessed periods is based mainly on the meteorological conditions, i.e. the values of sun radiation, temperature and precipitation in the period from April to September when the highest ozone concentrations are measured usually. The comparison of the period 2005–2007 with the previous three-year period 2004–2006 shows that the relative number of stations with exceedances slightly increased. The map with the 26th highest maximum daily 8-hour running averages shows clearly the slight increase of the territory with concentrations above 120 μg.m-3. As compared with the period 2004–2006 most stations (almost 70 %) recorded in the assessed period 2005–2007 the increased number of exceedance of the value of 120 μg.m-3 (the value of the target limit value). Based on the 2004–2006 average the above-the-limit concentrations of ground-level ozone occurred in 88 % of the territory of the Czech Republic; it was 97 % in 2005–2007. It is caused mainly by the fact that the year 2007 was the second warmest year (after 2003) as concerns the period under study, i.e. April–September, within 2000–2007, and thus also warmer (in the average for the whole Czech Republic by 1.2 C ) than the year 2004 which was included in the previous three-year period . The ground-level ozone concentrations generally grow with the increasing altitude which is confirmed also by the data measured for the year 2007 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.4.2.27 shows the 26th highest value of maximum 8-hour running average of ozone concentrations (three-year average) in 1996–2007. 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.4.2.29 shows the graph of the number of exceedances of the target value for ground-level ozone and Fig. II.4.2.30 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 1992–2007. Tab. II.4.2.12 Stations with the highest values of maximum daily 8-hour running
average concentrations of ozone
Fig. II.4.2.27 26th highest values of maximum 8-hour running average of ground-level
ozone concentrations (three-year average) in 1996–2007 at selected stations
II.4.2.1.7 Heavy metals None of the 74 localities recorded the exceedance of the limit value (500
ng.m-3). The first five localities with the highest annual average
are located in Ostrava. In 2007 the highest concentration was reached, similarly
as in the previous year, in the ZÚ locality Ostrava-Bartovice (101.5 ng.m-3).
The stations with the highest values of annual average concentrations are presented in Table II.4.2.14. Fig. II.4.2.31 Annual average concentrations of lead in the ambient air in
1996–2007 at selected stations
Cadmium 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 2007 cadmium was measured in 73 localities in total. The target value (5 ng.m-3) was exceeded, similarly as in some of the previous years, in the Liberec Region, and namely in the locality Tanvald (annual average 6.2 ng.m-3). Further, the highest, but already below-the-limit concentrations were measured, similarly as in 2006, in Ostrava in the localities Ostrava-Bartovice and Ostrava-Mariánské Hory. Most localities recorded a slight decrease of concentrations as compared with the year 2006, which is related with the decrease of PM10 concentrations in 2007 due mainly to more favourable dispersion and meteorological conditions, The target value must be met by 31.12.2012. The development of annual average concentrations in the period of 1996–2007 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 cadmium concentrations in selected localities in 2007 are presented in Fig. II.4.2.35. The stations with the highest values of annual average concentrations are presented in Table II.4.2.15. Fig. II.4.2.33 Annual average concentrations of cadmium in the ambient air in
1996–2007 at selected stations Arsenic 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 73 localities which monitored arsenic concentration in 2007 the target value (6 ng.m-3) was exceeded in 5 localities (Ostrava-Bartovice, Ostrava-Mariánské Hory, Prague 5-Řeporyje, Stehelčeves, and Kladno-Švermov). This target value must be met by 31.12.2012. The Ostrava station and the locality Kladno-Švermov recorded the exceedances also in previous years. In the station Stehelčeves in Kladno, the measurements began only two years ago, and the exceedance was indicated there for the first time. In Prague, at the Prague 5-Řeporyje station, the annual average has been increasing gradually over the recent 4 years, and in 2007 the target limit value was exceeded for the first time (within the recent 11 years) in spite of the fact that PM10 concentrations to which arsenic is bound, reached the lowest levels in 2007 (within the recent 4 years). Although the number of localities with limit value exceedances increased (from 3 to 5), in comparison with the year 2006, most localities recorded the decrease of annual average concentration due to more favourable dispersion and meteorological conditions, which is related with the decrease of PM10 concentrations in 2007. The development of annual average concentrations during the years 1996–2007 is apparent from Fig. II.4.2.36. 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.4.2.38). The stations with the highest annual average concentrations are presented in Table II.4.2.16. Fig. II.4.2.36 Annual average concentrations of arsenic in the ambient air in
1996–2007 at selected stations Nickel 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. 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 73 measuring localities, similarly as in previous years, exceeded the target value (20 ng.m-3) for nickel annual average concentrations. The annual average concentrations measured in Most, Prague and Plzeň exceeded the lower assessment threshold (10 ng.m-3). The highest annual average concentration was measured in the locality Most-ZÚ (10.6 ng.m-3) which did not have sufficient number of valid data for the calculation of annual average in the previous years. Nevertheless, as compared with the year 2006, more than half of the localities recorded a slight decrease of concentrations due to more favourable dispersion and meteorological conditions which is related with the decrease of PM10 concentrations in 2007. The stations with the highest values of the annual average concentrations are
presented in Table II.4.2.17. Fig. II.4.2.39 Annual average concentrations of nickel in the ambient air in
1996–2007 at selected stations
II.4.2.1.8 Benzo(a)pyrene When constructing the map of concentrations also emissions from transport are taken into account in addition to the stationary sources, and namely benzo(a)pyrene emissions from highways and main roads. The map was also created with regard to the gradient of benzo(a)pyrene air pollution concentrations with the altitude. The map for the year 2007 is based directly on the emissions from benzo(a)pyrene, not on the percentage share from PAH emissions as in the previous years. 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 form insufficient density of measurements.
A number of towns and villages were assessed, similarly as in the previous year,
as the areas with the exceeded target value (total 4.9 % of the territory of the
Czech Republic; in 2006 it was 9 %). The development of annual average concentrations in individual localities during 1997–2007 is apparent from Fig. II.4.2.41. The annual course of short-term concentrations (24-hour once in 3 or 6 days) of benzo(a)pyrene is presented in Fig. II.4.2.44. The fluctuations of monthly averages of concentrations for different types of stations in 2004–2007 are shown in Fig. II.4.2.43. The increase of concentrations during the winter periods confirm the influence of local furnaces. Fig. II.4.2.45 depicts benzo(a)pyrene concentrations in individual localities between 2004 and 2007 in relation to PM10 concentrations, resp. to its fine fraction PM2.5 to which benzo(a)pyrene is mainly bound.
Fig. II.4.2.41 Annual average concentrations of benzo(a)pyrene in 1997–2007 at
selected stations
II.4.2.1.9 Other substances 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 2007 the CHMI ISKO database received data on mercury concentrations in PM10 particles in the ambient air from 5 localities in total: from 4 localities in Ostrava and from the locality Karviná ZÚ where the highest annual average was measured (3.6 ng.m-3). The gaseous mercury Hg0 was measured in 2 localities (Ústí n.L.-město – annual average 4.1 ng.m-3 and Košetice – annual average was not calculated for insufficient number of valid data). 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.
Ammonia
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 2007. The highest annual average concentration was
measured, similarly as in the previous year, at the station Lovosice-MÚ (11.3
μg.m-3).
II.4.2.1.10 Trends of annual air pollution characteristics of SO2, PM10,
NO2, NOx and O3 for the period 1996–2007 Fig. II.4.2.46 shows the trends of SO2, PM10, NO2, NOx and O3 annual air pollution characteristics in the Czech Republic for the period of 1996–2007. Up to the year 2000 air pollution caused by SO2, PM10, NO2 and NOx 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 NOx concentrations and a significant increase of PM10 concentrations occurred. In 2004 this increasing trend of air pollution caused by PM10, NO2 and NOx 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 2007 the fluctuating trend of the levels of the above pollutants concentrations stopped and there was recorded a marked decrease of air pollution caused by SO2 and PM10 (both in towns and in the country), NO2 and NOx in all monitored air pollution characteristics. The steepest decrease is evident, after the previous increase, in hourly NO2 concentrations. The decrease of pollutants concentrations in the ambient air was given by more favourable meteorological and dispersion conditions, mainly in January and February 2007, as compared with the years 2005 and 2006. In ozone 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 slightly increased. In 2007 the average from the 26th highest maximum 8-hour running averages slightly decreased. On the contrary, there was a slight increase of the 76th values of maximum 8-hour running averages for the previous 3 years, resulting mainly from the fact that the April–September period of the year 2007 was warmer (in the average for the whole Czech Republic by 1.2 C ) than the year 2004 which was included in the previous three-year period but not taken into account for the assessment of the 2005–2007 period. 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.4.2.46 Trends of SO2, PM10, NO2, NOx
and O3 annual characteristics in the Czech Republic, 1996–2007
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