Graphic Yearbook

IV. AIR QUALITY IN THE CZECH REPUBLIC

IV.1 SUSPENDED PARTICLES

Air pollution caused by PM₁₀ and PM_2.5 fraction of suspended particles remains one of the main problems of air quality assurance in the CR. The exceedance of PM₁₀ and PM_2.5 limit values is still significant for including the respective settlements among the areas with limit value exceedances.

IV.1.1 Air pollution caused by suspended particles in the year 2013

Suspended particles of PM₁₀ fraction

The limit value for PM₁₀ 24-hour concentrations was exceeded in 2013 in 5.7 % of the territory of the CR with approx. 15.9 % of inhabitants, and for PM₁₀ average annual concentration in 0.7 % of the territory with approx. 4.8 % of inhabitants (Figs. IV.1.1 and IV.1.2).

The exceedance of the 24-hour limit value for PM₁₀ was recorded in 2013 in almost one third of stations (32.6 %, i.e. 42 stations of the total number of 129). In 2012 the daily limit value was exceeded in 42 % of stations (53 stations of 147; Fig. IV.1.14). In comparison with the year 2012 the 36^th highest concentration of PM₁₀ decreased in almost 60 % of stations. The average 36^th highest concentration of PM₁₀ in 2013 (48.9 µg.m^-3) was lower as compared with the year 2012 (51.3 µg.m^-3)¹. Consequently, the territory with the exceeded daily limit value for PM₁₀ decreased from 9.6 % with about one third of the CR population, to the already mentioned 5.7 % with approx. 15.9 % of inhabitants.

The most affected area of large coverage was, similarly as in the previous years (Figs. IV.1.10 and IV.1.11) the agglomeration of O/K/F-M where the daily limit value for PM₁₀ was exceeded in 2013 at most stations. However, the daily limit value for PM₁₀ was exceeded in all zones and agglomerations in at least one locality with the exception of the South-eastern zone (Fig. IV.1.3, Table XIII.4). In the agglomeration of Prague, in the agglomeration of Brno, in the North-eastern zone and in the Southwestern zone the exceedance of the limit value in 2013 was connected primarily with traffic loads; in other zones, however, the exceedances occurred also at the background urban, suburban and rural stations. In 2013 the annual limit value for PM₁₀ was exceeded in 7.4 % of stations, i.e. at 10 stations of the total number of 136 stations in the CR with sufficient amount of data for the evaluation; all exceedances were recorded only at the stations in the agglomeration of O/K/F-M (Table XIII.5, Fig. IV.1.12). In 2012 the exceedances of the annual limit value were recorded in 10.8 % of stations (15 stations of 138; Fig. IV.1.14). The annual average concentration of PM₁₀ decreased in comparison with the year 2012 in 54 % of stations and the average annual concentration in 2013 (26.8 µg.m^-3) was slightly lower in comparison with the year 2012 (27.3 µg.m^-3)¹. The territory with the annual limit value exceedances in 2013 decreased to 0.7 % with approx. 4.8 % inhabitants from 0.9 % of the territory with approx. 5.2 % of inhabitants evaluated in 2012.

The concentrations of PM₁₀ show a clear annual course with the highest concentrations in the cold months of the year (Figs. IV.1.4, IV.1.5, IV.1.6). Higher concentrations of PM₁₀ in the ambient air during the cold part of the year are connected both with higher emissions of particles from seasonal heat sources (e.g. the share of local heating in PM₁₀ and PM_2.5 emissions in the CR is 41 % and 59 % respectively – Figs. IV.1.19 and. IV.1.20), and with deteriorated dispersion conditions, more frequent in winter months.

In 2013 the highest concentrations were measured in the months January–March, namely due to frequent unfavourable dispersion conditions. On the contrary, the last three months of the year were, with regard to dispersion conditions, more favourable and recorded the above-the-normal temperatures (see Chapter III). Along with the lower intensity of heating this resulted in lower average monthly concentrations, i.e. in their decrease. The lower intensity of heating and the subsequent decrease of emissions from heating from October to December can be assumed on the basis of degree days comparison in individual months of the heating season (Fig. III.4). Detailed analysis of the reasons for higher concentrations of PM₁₀ in the first months of the year 2013 is presented in Chapter III.

Suspended particles of PM_2.5 fraction

The level of air pollution caused by PM_2.5 in 2013 did not changed significantly in comparison with the year 2012. The annual limit value for PM_2.5 was exceeded in 2.4 % of the CR territory with approx. 9.6 % of inhabitants (Fig. IV.1.7). In 2012 the same part of the territory of the CR with the exceeded limit value was recorded with approx. 10.2 % of inhabitants. The exceedances were recorded at six stations in the agglomeration of O/K/F-M and at one station in the agglomeration of Prague, at one station in the Moravia-Silesia zone and at one station in the Central Moravia zone (Table XIII.6, Fig. IV.1.9) of the total number of 46 stations (i.e. exceedances in 19.6 % of stations); in 2012 exceedances were recorded at nine stations of 45 (Fig. IV.1.14). In comparison with the year 2012 the average annual concentration of PM_2.5 increased in almost 60 % of stations, nevertheless the average annual concentration of PM_2.5 in 2013 was only slightly higher as against the year 2012 (20.9 vs. 20.3 µg.m^-3); the evaluation was based on the same set of stations in both years.
Air pollution caused by PM_2.5 occurs mainly in the cold part of the year (Fig. IV.1.9); higher concentrations in the cold part of the year are similarly as those in PM₁₀ caused by emissions from heating and deteriorated dispersion conditions.

The ration of PM_2.5 and PM₁₀ fractions of suspended particles

The ratio between PM_2.5 and PM₁₀ fractions is not constant, it shows a certain seasonal course, and at the same time it is dependent on the locality (Fig. IV.1.8). In 2013 the ratio, in the average from 32 localities in the CR measuring both PM_2.5 and PM₁₀ and with sufficient number of values, ranged from 0.68 (August) to 0.82 (January) with lower values in the summer period. In Prague, where the annual course is influenced by a large share of traffic localities, this ratio ranged from 0.56 (September) to 0.75 (March), in Brno from 0.7 (May) to 0.85 (November) and in the Moravia-Silesia region from 0.69 (May) to 0.85 (January). When comparing the ratio with regard to the classification of localities, the ratio in rural localities is from 0.78 (July) to 0.93 (December), in urban localities from 0.7 (August and September) to 0.81 (February and March), in suburban localities from 0.67 (May) to 0.84 (December), in traffic localities from 0.61 (September) to 0.75 (January) and in industrial localities 0.63 (July) to 0.91 (January).

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 (Gehrig, Buchmann 2003). The higher PM_2.5/PM₁₀ fraction ratio due to combustion is observed also at industrial stations.

The lowest PM_2.5/PM₁₀ ratio is at traffic localities (Fig. IV.1.8). 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 tyre, break lining and road surface abrasion. The share of the coarse fraction at traffic stations increases also due to the re-suspension of particles following winter spreading of roads. The growth of PM₁₀ concentrations can be caused also by the increased abrasion of road surface by spreading and the subsequent re-suspension of the abraded material (EC 2011).

IV.1.2 The development of PM₁₀ and PM_2.5 concentrations

The concentrations of PM₁₀ suspended particles, similarly as in other pollutants, decreased significantly in the 90s of the last century. This was caused by marked decrease of emissions of TSP and precursors of suspended particles (SO₂, NO_x, NH₃ and VOC) in the period 1990–2001 due to the legislative changes, restructuring of economy and modernization or closure of the operated sources (more details see Chapter II., Fig. II.1). After the year 2001 the decrease of emissions continued at a slower rate (Fig. II.2), which resulted in the fact that pollutants concentrations were influenced mainly by the prevailing meteorological and dispersion conditions in the given year. In almost all localities in the CR an increasing trend of air pollution caused by PM₁₀ was apparent from 2001 to 2003. In 2003 so far the highest values of PM₁₀ concentrations were measured in the period after the year 2000. High PM₁₀ concentrations in 2003 were caused both by unfavourable dispersion conditions in February and the belowthe-normal precipitation amounts. After a short change in 2004, when routine monitoring of PM_2.5, fraction started, high concentrations of suspended particles were recorded again in the years 2005 and 2006, mainly due to the long episodes with unfavourable dispersion conditions. In 2007–2009, on the contrary, there were more favourable dispersion conditions and the concentrations of particles significantly decreased in comparison with the years 2003, 2005 and 2006. In the year 2008 lower concentrations were caused probably also by more marked decrease of emissions of some precursors of particles during the temporary decline in certain sectors due to the economic crisis (more details see Chapter II.). The subsequent increase of concentrations of suspended particles in 2010 was given mainly by the repeated occurrence of unfavourable meteorological and dispersion conditions in the winter period at the beginning and at the end of the year and by the coldest heating season since 1996 (Fig. III.1). During the last three years since 2010 the concentration of suspended particles have been decreasing. The annual average concentration of PM₁₀ has remained below the limit value in the long term, on the contrary, the annual average concentration of PM_2.5 and the 36^th highest daily concentration of PM₁₀ fluctuates around the limit value (in all cases averaged for all types of localities and the whole CR; Figs. IV.1.15 and IV.1.16).

IV.1.3 Emissions of PM₁₀ and PM_2.5

The combustion of fuels and other industrial activities result in the production of aerosol emissions which can be solid, liquid or mixed. The Czech legislation defines these emissions as solid pollutants (TZL), the foreign literature refers to Total Suspended Particulate Matter (TSP). With regard to the effects on human health there were defined the size groups called PMx (Particulate Matter). They contain the particles smaller than x µm (aerodynamic diameter). Most often emission inventories define the PM₁₀ and PM_2.5 size fractions. Emissions of TSP have various size and chemical compositions according to the character of the source and the way of formation. They may contain heavy metals and they are carriers of VOC.

Emission inventories of PM₁₀ and PM_2.5 particles carried out according to valid methods include only the emissions produced by primary sources. In comparison with emissions of other pollutants PM emissions are emitted into the air from a large number of groups of sources. Apart from the sources from which these substances are discharged in a controlled manner, significant amount of PM emissions have their origin in fugitive sources (quarries, landfills of dusty materials, operations with dusty materials etc.). The ambient air quality can be influenced also by emissions of PM produced by re-suspension of dust, not included in emission inventories. The share of individual groups of sources in PM₁₀ and PM_2.5 emissions in 2012 is depicted in Figs. IV.1.19 and IV.1.20. The main source of PM emissions is represented by the sector of local household heating; its share in air pollution caused by PM₁₀ amounted to 40.8 % and by PM_2.5 to 59.2 %. Other significant sources of PM₁₀ emissions include agricultural activities, where these emissions are produced during tillage, harvest and cleaning of agricultural crops in fields. This sector contributed with 13.1 % of PM₁₀ emissions. With regard to the effects on human health, most significant are the emissions of PM caused by traffic, mainly from fuel combustion in compression ignition engines, producing the particles with the size from units to hundreds of nm (Vojtíšek 2010). Road freight transport over 3.5 t and the share of passenger car transport in PM₁₀ emissions was 6.5 % and in PM_2.5 emissions 9.6 %.

The share of households using solid fuels for heating did not changed in the period 2007–2012 significantly, and therefore the trend of PM₁₀ and PM_2.5 emissions is influenced especially by the character of heating seasons (Figs. IV.1.21 and IV.1.22). The decrease of emissions is influenced especially by the natural renewal of the car fleet, the decrease of agricultural production and the implementation of emission ceilings of TSP for LCP sources since 2008.

With regard to the fact that the main source of PM₁₀ and PM_2.5 emissions is represented by the sector of local household heating, the production of emissions of these pollutants is distributed throughout the whole inhabited territory of the CR (Figs. IV.1.23 and IV.1.24). In the territory of the CR divided into 5x5 km squares there are localities with major energy producers combusting solid fossil fuels (primarily the Moravia-Silesia region and the Ústí nad Labem region). The share of traffic is apparent mainly in big cities.

Tab. IV.1.1 Overview of localities with the exceedance of the limit value for annual average PM₁₀ concentration, 2009–2013

Tab. XIII.4 Stations with the highest numbers of exceedances of the 24-hour limit value of PM₁₀

Tab. XIII.5 Stations with the highest values of annual average concentrations of PM₁₀

Tab. XIII.6 Stations with the highest values of annual average concentrations of PM_2.5

Fig. IV.1.1 Field of the 36^th highest 24-hour concentration of PM₁₀ in 2013

Fig. IV.1.2 Field of annual average concentration of PM₁₀ in 2013

Fig. IV.1.3 Numbers of exceedances of the limit value for 24-hour concentration of PM₁₀ in 2013

Fig. IV.1.4 Annual course of average monthly concentrations of PM₁₀ (averages for the given type of station), 2013

Fig. IV.1.5 Stations with the highest exceedance of LV for 24-hour concentrations of PM₁₀ in 2013

Fig. IV.1.6 Stations with the highest exceedance of LV for annual concentrations of PM₁₀ in 2013

Fig. IV.1.7 Field of annual average concentration of PM_2.5 in 2013

Fig. IV.1.8 Average monthly PM_2.5/PM₁₀ ratio in 2013

Fig. IV.1.9 Stations with the highest exceedance of LV for annual concentrations of PM_2.5 in 2013

Fig. IV.1.10 36^th highest 24-hour concentrations and annual average concentrations of PM₁₀ in 2003–2013 at selected stations with UB, SUB, I and T classification

Fig. IV.1.11 36^th highest 24-hour concentrations and annual average concentrations of PM₁₀ in 2003–2013 at selected rural (R) stations

Fig. IV.1.12 Annual average PM₁₀ concentrations at the stations with the exceedance of the limit value, 2009–2013

Fig. IV.1.13 Annual average concentrations of PM_2.5 in the ambient air in 2004–2013 at selected stations

Fig. IV.1.14 Share of localities with the exceedance of the limit value for 24-hour concentrations and annual average concentrations of PM₁₀ and PM_2.5, 2000–2013

Fig. IV.1.15 Trends of PM₁₀ and PM_2.5 annual characteristics in the Czech Republic, 1996–2013

Fig. IV.1.16 Trends of selected characteristics of PM₁₀ (index, year 1996 = 100), 1996–2013; (index, year 2000 = 100), 2000–2013 and PM_2.5 (index, year 2004 = 100), 2004–2013