Assessment of the status of the air pollution is based on air pollution limit values as specified in the Decree of the Federal Committee for the Environment of October 1, 1991, attached to Act No. 309/1991 Coll., the Clean Air Act in the wording of Act No. 211/94 Coll. (This Table has been copied over from the above Decree, with some formal modifications.)

Tab. 2.2.1 Limit values for the Czech Republic

In 2001 the transport and dispersion model Symos�97 in combination with data measured was used for the purpose of construction of the field of annual arithmetic means of SO₂, to some extent of NO_x and SPM (see Chapter 2.2–2.3). (The model was developed by CHMI in co-operation with EKOAIR company.) This model uses digitally processed terrain DMT 200 developed in VTÚ Dobruška. The Symos�97 model is a useful supplement of the SO₂ air pollution assessment, to some extent for NO_x and SPM, in localitites with deficient measurement.

The field of annual arithmetic means of NO_x concentrations and 95th percentiles was produced by combining the measured NO_x concentrations with statistically supported estimates of ambient air pollution level in localities not covered by adequate measurements, taking into account the categorisation of the country�s territory in terms of emission densities and Symos�97 model.

Combined map presentation using an estimation of the spatial distribution of fields of the ambient air pollution characteristics along with an indication of data measured in measuring stations (spot symbols method¹) [6] was used in 2001 for the presentation of the spatial distribution of annual arithmetic means and 95th percentiles of SO₂, SPM and NO_x. In the maps automated monitoring stations (AMS) are differentiated from manually operated stations. When constructing maps of SO₂ and NO_x concentration fields, the main emphasis was laid on AMS stations. In most cases, values collected from manually operated stations were used solely as complementary information, especially in less afflicted areas.

In case of the combined map SPM annual mean presentation and 95th percentile, AMS stations measuring PM₁₀ fraction were converted to SPM (coefficient 1.2) and identified with other symbol.

The share taken by the respective concentration category, expressed as a percentage of the area afflicted is specified for each category on maps showing fields of ambient air pollution characteristics.

Presented in this part are also tables that list stations with the highest relative frequency of short-term IH_k exceedence and the highest values of 95th percentiles of half-hour pollutant concentrations. Also tabulated are overviews of the maximum daily concentrations (including date of occurrence), highest annual arithmetical means, highest relative (absolute) frequency of IH_d exceedence, and the highest values of 95th percentiles (90th percentiles) of daily pollutant concentrations. When the frequency of the daily ambient air pollution limit exceedence was markedly higher for only one pollutant in a given region, the table contains, for the purpose of clarity, the values for the other pollutants as well. This part also contains a table of the highest half-hour pollutant concentrations recorded at Czech stations in 2001.

The maps and tables list only the stations for which the calculated ambient air pollution characteristics have satisfied the conditions of publication (see the Tabular Survey [2]). Expert estimates were also resorted to when constructing maps of pollutant concentration fields to cover sites with insufficient density of measurements (these are almost exclusively sites with low emission densities and low air pollution levels).

2.2.1 Air pollution situation based on individual pollutants

Sulphur dioxide

The 2001 situation in sulphur dioxide in the Czech Republic is shown in maps of fields of annual arithmetic means and 95th percentiles of daily concentrations with the depiction of the measured values at the stations (Figs. 2.2.1 and 2.2.2). Almost on the entire Czech Republic�s territory SO₂ annual arithmetic means did not exceed 20 μg.m^-3 in 2001. On the entire country�s territory except for a very small area, the 95th percentile of SO₂ daily averages stayed under 50 μg.m^-3.

The only affected area where SO₂ air pollution limit values were occasionally exceeded is the north Bohemia, mainly the Krušné hory Mts. basin region. In this area air pollution level above 20 μg.m^-3 was recorded occasionally in 2001 (annual arithmetic mean) which represents one third of the limit value. The highest values of this air pollution characteristic were recorded at Teplice-OHS and Úštěk stations in the Litoměřice district (see Tables 2.2.2, 2.2.3, 2.2.4 and 2.2.5). The relative frequency of the exceedence of the daily limit value (IH_d) in more than 1 % of cases was recorded only at the station Teplice-OHS (Table 2.2.4).

Moderate increase of SO₂ concentrations, as compared with the year 2000, was recorded at the stations in the northern part of the Karviná district where the situation may be influenced by pollution from Poland, and namely from the Katowice agglomeration. Other areas of the Czech Republic showed very low SO₂ pollution levels, markedly below the limit values.

Suspended particulate matter

SPM pollution in the Czech Republic in 2001 is illustrated in maps of fields of annual arithmetic means and 95th percentiles of daily concentrations with the depiction of the measured and recalculated values at the stations (Figs. 2.2.3. and 2.2.4). On 88 % of the Czech Republic territory, SPM annual arithmetic means did not exceed 30 μg.m^-3. Almost on the entire Czech Republic�s territory annual arithmetic means of SPM concentrations amounted to maximum 50 μg.m^-3 in 2001. On 97 % of the territory the 95th percentile of annual files of daily averages did not exceed 80 μg.m^-3.

In the past the Ostrava Region (now part of the Moravian-Silesian Region) was, and in terms of the size of area affected with concentrations between 40–60 μg.m^-3 (annual arithmetic mean) continues to be the region which suffers from SPM most of all. In 2001, similarly as in previous years, the highest exceedence of limit values occurred in Prague at two HS stations exposed to traffic and then at the AMS station in Mělník (Tables 2.2.3, 2.2.4 and 2.2.5). The highest maximum daily SPM concentrations were recorded in the eastern part of the Moravian– Silesian Region and some AMS stations recorded the limit values exceedences (annual arithmetic mean) after recalculation from PM₁₀ fraction. Similarly as in SO₂, it was mainly the northern part of the Karviná district where certain increase of air pollution caused by SPM was recorded in comparison with the year 2000. Apparently, this was caused by the Polish sources from the Katowice agglomeration.

Apart from the above areas air pollution above 40 μg.m^-3 (annual arithmetic mean) was recorded in Brno, in the zone from Prague to Litoměřice and in the basin region of the Krušné hory Mts. The 95th percentile of SPM concentrations above 80 μg.m^-3 were recorded in the eastern part of the Moravian–Silesian Region, in the Prague centre and in Mělník and Litoměřice districts.

Nitrogen oxides

Maps of fields of annual arithmetic means and 95th percentiles of daily concentrations with the indication of the measured values at the stations illustrate NO_x pollution in the Czech Republic in 2001 (Figs. 2.2.5 and 2.2.6). On 89 % of the country�s territory the annual arithmetic means of NO_x concentrations reached 20 μg.m^-3 at the maximum. On 97 % of the territory the 95th percentile of annual files of daily means was lower than 70 μg.m^-3.

The heaviest NO_x pollution has always been recorded in Prague, where in the past years the daily air pollution limits were exceeded in more than 5 % of cases at almost all stations. This is characteristic also for 2001, where the highest exceedences were recorded again at two HS stations exposed to traffic (Tables 2.2.3, 2.2.4 and 2.2.5). These exceedences (95th percentile) were recorded at some urban stations in northwestern and central Bohemia, in the eastern part of the Moravian–Silesian Region and in Hradec Králové, Brno and Zlín.

Ground-level ozone

Ground-level ozone has been observed in the AIM monitoring network since 1992. In 2001, measurements were carried out at 62 stations throughout the Czech Republic.

The current limit value for ozone 160 μg.m^-3 (8-hour average) was exceeded only in 9 cases at 6 stations in 2001. The highest 8-hour average concentration 175.6 μg.m^-3 was recorded on 31 July 2001 at Tušimice station.

The warning alert threshold 360 μg.m^-3 was not exceeded in 2001. The information alert threshold 180 μg.m^-3 was exceeded in 25 cases at 9 stations. The maximum hour ozone concentration (198.3 μg.m^-3) was measured at Přimda station on 31 July 2001.

The exceedence episodes did not occur in 2001. The 8-hour limit value was exceeded repeatedly only on 27. 5., 27. 6., 7. 7. and 31. 7.; the concentrations ranged between 162.2 and 175.6 μg.m^-3.

The hourly limit value was exceeded repeatedly only on 27. 6., 7. 7., 31. 7., 19. 8. and 27. 8.; the concentrations ranged between 180.2 and 198.3 μg.m^-3.

The endangered areas with regard to ground-level ozone effects on ecosystems are defined on the basis of AOT40 exposure index.

Fig. 2.2.7 shows the field of AOT40 exposure index values for forests in the Czech Republic in 2001. The threshold value for the protection of forests 10,000 ppb.h is exceeded on 94.5 % of the total country�s territoty.

Fig. 2.2.8 depicts the field of AOT40 exposure index values for farm crops and semi-natural vegetation. The threshold level for the protection of this type of ecosystems was set to 3,000 ppb.h and almost the whole territory of the Czech Republic was affected by the exposure over this threshold level.

Carbon monoxide

Carbon monoxide measurements have been taken in the country�s automated ambient air pollution monitoring system since 1993. In 2001 they were recorded at 57 sites throughout the Czech Republic.

The half-hour ambient air pollution limit value (IH_k) 10,000 μg.m^-3 was exceeded in 2,198 cases at 6 stations. All the stations are operated by the Public Health Service. The following table shows the exceedence frequencies.

The absolute IH_k maxima were recorded at Public Health Service stations Praha 5-Svornosti, Praha 8-Sokolovská and Praha 5-Řeporyje. Concentrations presented in the database (62–500 μg.m^-3) correspond to the gauge of the used measuring instruments. Thus it is probable that some of the stated concentrations might have been higher and remained unrecorded. The daily limit value (IH_d) 5,000 μg.m^-3 was exceeded at 3 stations in 295 cases. The highest frequency of exceedence was recorded again at Public Health Service stations Prague 5-Svornosti and Prague 8-Sokolovská: 52.6 %, resp. 35.0 %. Besides, the exceedence frequency at the station Prague 5-Řeporyje amounted to 4.5 %. The highest daily average level was measured at Prague 5-Svornosti station on 20 January andamounted to 13,725 μg.m^-3. The high levels of relative IH_d exceedence frequencies for CO correspond to those for NO_x and SPM at these stations.

In general, the number of limit values exceedences was higher in 2001 than in 2000; the measured daily maximum was somewhat lower.

Lead

The exceedence of the annual limit value of this pollutant has not been recorded in long terms in the Czech Republic. The highest annual average lead concentrations did not reach 0.1 μg.m^-3 in 2001 (see the Tabular Survey).

Cadmium

In 2001 the cadmium concentrations were close to the limit value at the HS station Tanvald (9.7 μg.m^-3), where the limit values were repeatedly markedly exceeded in the past. The CHMI station Souš and the HS station Praha 4-Ant. Staška reported the cadmium annual average concentrations above one half of the annual limit value (6.5 μg.m^-3 and 5.6 μg.m^-3 respectively).

Tab. 2.2.2 Highest daily pollutant concentrations at stations in the Czech Republic in 2001

Tab. 2.2.3 Stations with highest annual arithmetic means of pollutant concentrations, the Czech Republic 2001

Tab. 2.2.4 Stations with highest relative (absolute) frequency of IH_d exceedence, the Czech Republic 2001

Tab. 2.2.5 Stations with highest values of 95th (90th) percentiles of daily pollutant concentrations, the Czech Republic 2001

Tab. 2.2.6 Stations with highest relative frequency of short-term exceedence of IH_k, the Czech Republic 2001

Tab. 2.2.7 Stations with highest values of 95th percentiles of half-hour pollutant concentrations, the Czech Republic 2001

Tab. 2.2.8 Highest half-hour (3-hour) pollutant concentrations at stations, the Czech Republic 2001

Fig. 2.2.1 Fields of annual arithmetic means of concentrations with presentation of measured values at stations, sulphur dioxide, 2001

Fig. 2.2.2 Fields of 95th percentiles of daily concentrations with presentation of measured values at stations, sulphur dioxide, 2001

Fig. 2.2.3 Fields of annual arithmetic means of concentrations with presentation of measured and recalculated values at stations, SPM, 2001

Fig. 2.2.4 Fields of 95th percentiles of daily concentrations with presentation of measured and recalculated values at stations, SPM, 2001

Fig. 2.2.5 Fields of annual arithmetic means of concentrations with presentation of measured values at stations, nitrogen oxides, 2001

Fig. 2.2.6 Fields of 95th percentiles of daily concentrations with presentation of measured values at stations, nitrogen oxides, 2001

Fig. 2.2.7 Fields of AOT40 ozone exposure index for forests, 2001

Fig. 2.2.8 Fields of AOT40 ozone exposure index for farm crops, 2001

2.2.2 Development of air pollution over the longer term

Figs. 2.2.9, 2.2.10 and 2.2.11 contain map diagrams² [6] illustrating profiles of principal ambient air pollution characteristics (annual arithmetic means and 95th percentiles) of basic pollutants (SO₂, SPM and NO_x) sorted in districts, showing the amount by which the relevant ambient air pollution limits were exceeded. These characteristics represent estimates of values averaged over a district within the 1990–2001 period, calculated according to the methodology based on the year 1996. It is to be noted at this point, however, that this regionalized assessment of principal ambient air pollution characteristics� courses for the principal pollutants in the Czech Republic is based on different numbers of accessible measuring stations in individual districts.

Fig. 2.2.9 illustrating the course of sulphur dioxide air pollution characteristics in 1990–2001 shows a marked downward trend in SO₂ pollution in all districts of the Czech Republic. The steepest decrease was recorded in north Bohemia and in Prague where the highest levels were recorded in early 90s. The most marked decrease of SO₂ concentration was recorded in 1994 throughout the whole territory of the Czech Republic. In the period between 1994 and 2001 the regionalized means of SO₂ air pollution characteristics did not exceed the limit values set by the Decree of the Federal Committee for the Environment in any district of the Czech Republic. In 1998–2000 further gradual decrease of SO₂ pollution occurred. In 2001 the downward trend ceased and the measured values stagnated. In the recent four-year period 1998–2001 no exceedences of the current limit value were recorded at any measuring station.

The suspended particulate matter (SPM)³ air pollution development (Fig. 2.2.10) shows similar falling trend in the Czech Republic within 1990–2000 period as in SO₂ pollution, less marked in the early 90s, mainly in the eastern part of the Moravian– Silesian Region. In this region this type of air pollution stagnated until 1996. In 1997–1999 a marked downward trend was recorded throughout the whole territory of the Czech Republic. This downward trend ceased in 2000 and since then the SPM air pollution has rather stagnated; in most districts this was evident also in 2001. In the eastern part of the Moravian–Silesian Region and in northern Bohemia a slight increase of SPM concentrations was recorded. Since 1998 the regionalized means of SPM air pollution characteristics have not exceeded the limit values set by the Decree of the Federal Committee for the Environment in any district.

The falling trend of SO₂ and SPM concentrations of the 90s results from the concurrence of several factors: efficient direct environmental measures applied to the sources of air pollution and changes in favour of gas heating, which led to the decline in SO₂ and solid particles total emissions, and more favourable meteorological and dispersion conditions, mainly in winter months. In the end of 2000 and 2001, however these conditions were less favourable than in the end of the 90s (see Chapter 2.4) and, consequently, the decreasing trend of these pollutants concentrations ceased.

In respect to nitrogen oxides, a slightly increasing trend of air pollution was observed until 1997 (Fig. 2.2.11). This was caused mainly by the increasing share of road transport. The increase of NO_x concentrations in the districts of south Moravia was recorded in 1995 with the installation of new urban stations by district or municipal authorities. In the same year one HS station in Děčín was moved to a more exposed site. In 1998 and 1999 this trend was broken and, on the contrary, a slight decrease of NO_x concentrations was recorded due to lower emission from stationary sources in the winter months of 1998, and especially in Moravian districts, probably due to the fact that some sources were shut down and to a certain setback in production in 1999. In 2000, in most cases stagnation of this type of pollution prevailed. In the Šumperk district the steep decrease of NO_x concentrations in 2000 was caused by the closing of two exposed stations. In 2001 the stagnating trend continued in most districts. Prague stations recorded a slight decrease of air pollution caused by NO_x.

Fig. 2.2.12 illustrates the development of annual air pollution characteristics of basic pollutants monitored in the long term (1982–2001) for the northwest area, Prague and Moravian-Silesian Region. Generally, beginning from the year 1988 a downward trend can be observed, both in SO₂ and SPM, in air pollution of the Czech Republic and this decrease is markedly significant after 1996. After 1996 the decrease in NO_x pollution is apparent in the northwest area and in the Moravian-Silesian Region as well. In Prague this trend was observed after 1997 and in 2001 the slight decrease of NO_x concentrations was confirmed. In respect to air pollution caused by SO₂ the monitored areas reported stagnation of this type of air pollution in 2001. A slight increase of air pollution caused by SPM occurred in the northwest area and in the Moravian-Silesian Region.

Fig. 2.2.13 presents the long-term development of air pollution and the course of temperatures in winter seasons. When comparing the course of temperature of the winter season of 2001/2002 with comparable winter season of 1994/1995, 1987/1988 and 1982/1983 a marked decrease of SO₂ and SPM is evident in Prague, northwest Bohemia and in the Moravian-Silesian Region. The above three areas reported also a slight decrease of NO_x levels during the comparable winter seasons 2001/2002 and 1994/1995.

2.2.3 Air quality summary assessment

It is relatively complicated to describe air pollution by listing the levels of ambient air pollution characteristics for substances measured at a particular site, and their values relative to air pollution limits; this would also depend on the range of substances monitored on a given site. The efforts to substitute such a complicated description of air quality situation in a locality by an explicative, best of all verbally expressed classification have resulted in variously constructed air quality indices [7, 8]. When designing an air quality index the generally measured ambient air pollution levels are �standardised� using the air quality limits values prescribed and, being dimensionless numbers, levels of individual substances standardised in this way are combined. The values generated are then allocated to classification levels. Such constructions usually face a pitfall in that the application of mathematical operations in fact leads to the implementation of the new, legally void limit values being determined for the substances under review.

The map in Fig. 2.2.15 represents summary air quality assessment for the year 2001 taking into account the ambient air pollution limit values set by the Decree of the Federal Committee for the Environment. In its compilation, fields of each pollutant�s regional distributions were used and analysed by means of map algebra based on the classification listed in Table 2.2.9. In accordance with the legislative requirements the inputs to summary assessment specifically include:

� fields of annual arithmetic mean concentrations of

- SO₂
- SPM
- NO_x
- lead
- cadmium

� fields of 95th percentiles of daily concentrations of

- SO₂
- SPM
- NO_x.

In comparison with the preceding years, when exceedences of mainly SO₂ and SPM level values were dominant, after 1998 classification of the polluted to heavily polluted classes is characterized almost exclusively by frequency of exceedence of NO_x daily limit values resulting from the ever increasing road transport.

Graphs in Fig. 2.2.14 show the development of population and area proportions in the stated air quality classes (% of the total population and territory of the Czech Republic). The graphs demonstrate a visible increase in classes I and II and a decrease in classes III to V. The graph in Fig. 2.2.14 shows that this positive trend broke or slightly deteriorated after 1999.

Table 2.2.10 lists settlements with populations over 3,000, located in areas of polluted to heavily polluted air (class III to V). In contrary to 1996 year a noticeable decrease in amount of municipalities, from 47 to 8, included in classes of polluted to heavily polluted air quality (according to the classification shown in Table 2.2.9) was recorded in 1999. Table 2.2.10, on the contrary, shows that in 2001 the number of settlements in the above classes increased to 27 (from 15 in the year 2000).

Notes:

¹ The method of spot symbols [6] is one of the methods of cartographic presentation using geometrical, pictographic and literal symbols and signs. It is used for depicting the location and quality of discrete objects. The Yearbook uses this method for the presentation of air pollution monitoring stations distribution. The size of the symbols does not express the quantity of the phenomenon; various colours for the respective classes of basic pollutants concentrations are used instead.

² The method based on map diagrams is one of the methods of cartographic presentation using spot diagrams which represent both the quality and the quantity of the given phenomenon (absolute or relative values). The map diagrams depict summary values for a given territory in the centre of which they are located, i.e. not for individual spots. The Yearbook uses this method for depicting the developments over time and showing the volume of air pollution characteristics of principal pollutants in individual districts of the Czech Republic.

³ Long-term series of air pollution are characterised by SPM concentrations regardless the size of particles. All automated CHMI stations have been measuring the PM₁₀ fraction since 1996. When using these measurements to estimate regional SPM means, a conversion coefficient 1.2 was applied.

Tab. 2.2.9 Regional classification of ambient air quality

Tab. 2.2.10 Settlements with population over 3,000 in zones of ambient air quality classes No. III to No. V, 2001

Fig. 2.2.9 Principal ambient air pollution characteristics - annual arithmetic means and 95th percentiles of daily average sulphur dioxide concentrations, by districts, between 1990 and 2001

Fig. 2.2.10 Principal ambient air pollution characteristics - annual arithmetic means and 95th percentiles of daily average SPM concentrations, by districts, between 1990 and 2001

Fig. 2.2.11 Principal ambient air pollution characteristics - annual arithmetic means and 95th percentiles of daily average nitrogen oxides concentrations, by districts, between 1990 and 2001

Fig. 2.2.12 Annual assessment for 1982-2001 in Prague, Northwest Region and Moravian-Silesian Region

Fig. 2.2.13 Assessment of 1982/1983-2001/2002 winter seasons in Prague, Northwest Region and Moravian-Silesian Region

Fig. 2.2.14 The development of population and area proportions in air quality classes

Fig. 2.2.15 Classification of the Czech Republic's territory in terms of air quality summary assessment, 2001