IV.7 SULPHUR DIOXIDE (SO₂)
 

IV.7.1 Air pollution caused by SO₂ in the year 2013

Air pollution caused by SO₂ in the year 2013 with regard to the limit values for the protection of human health

In 2013 neither the limit value for the hourly SO₂ concentration nor for the 24-hour SO₂ concentration were exceeded in the CR at any measuring station (Tables XIII.1 and XIII.2). There were only two localities in the Ústí nad Labem region where there was measured 1-hour concentration of SO₂ exceeding the limit value 350 µg.m^-3 (Výsluní 513 µg.m^-3 and Krupka 390 µg.m^-3), however, the tolerated number of the limit value exceedances (24x) was not exceeded. The station Výsluní (ČEZ) is classified as industrial rural, and thus it can be assumed that it is affected by the sources from the Podkrušnohorská basin in the foothills of the Krušné hory Mts. The background station Krupka is probably influenced by the local source (details in Annex II).

The 25^th highest SO₂ concentration reached the maximum values at the stations: Ostrava-Radvanice 129 µg.m^-3, Lom 124 µg.m^-3 and Teplice 105 µg.m^-3 . The maximum 24-hour concentrations of SO₂ did not exceed the limit value 125 µg.m^-3 (Ostrava-Radvanice 97 µg.m^-3, Lom 94 µg.m^-3 and Teplice 84 µg.m^-3). The 4^th highest 24-hour SO₂ concentration reached the maximum values at the stations Ostrava-Radvanice 79 µg.m^-3, Lom 60 µg.m^-3 and Věřňovice 57 µg.m^-3.

The map of the field of the 4^th 24-hour SO₂ concentration in 2013 (Fig. IV.7.1) shows that in 99.7 % of the CR territory the concentration of this pollutant did not reach 50 µg.m^-3, and thus only in approx. 0.3 % of the territory of the CR SO₂ concentrations exceeded the lower assessment threshold. This small area, with SO₂ concentrations exceeding 50 µg.m^-3, occurred mainly in the Ústí nad Labem region, in the part of the Podkrušnohorská basin, in the districts Most and Teplice.

Figs. IV.7.2 and IV.7.3 depict the courses of 1-hour and 24-hour SO₂ concentrations at selected stations in 2013.

 
Air pollution caused by SO₂ with regard to the limit values for the protection of ecosystems and vegetation

In 2013 neither the limit value for the annual average concentration nor the limit value for the winter average concentration were not exceeded in rural localities (Tables XIII.17 and XIII.18). The highest winter average concentration in 2013 was recorded in the localities Krupka (14.9 µg.m^-3) and Lom (14.8 µg.m^-3), the annual average concentration reached its maximum in the locality Věřnovice (10.1 µg.m^-3). The maps of the field of annual average concentration 2013 and of the average concentration for the winter period 2013/2014 (Figs. IV.7.4 and IV.7.5) show the exceedance of the limit value in a small part of the Ústí nad Labem region, in the area between the cities Most and Litvínov. This exceedance is apparent in the map constructed by model calculation based on the emission from the year 2012. This fact can influence to a certain extent the shape of the field of SO₂ concentrations. The decrease of the annual average concentration of SO₂ at the station Lom in 2013 corresponds with the decrease of SO₂ emissions in the district Most based on the preliminary results of emission records for the year 2013.

The map was constructed from the data of all background stations measuring SO₂ with regard to their classification; only rural stations are marked with spot symbols.

This chapter is closed by the graphs of the courses of 24-hour SO₂ concentrations at selected stations, related to the limit value for the winter and annual averages (Figs. IV.7.6 and IV.7.7).

IV.7.2 The development of SO₂ concentrations

After the year 1998 there was recorded, in connection with coming into force of the Act No. 309/1991 Coll., and meeting the required emission limit values, a marked decrease of SO₂ concentrations. Since then the annual average concentrations of this pollutant have not exceeded the set limit value 20 µg.m^-3 at rural stations (Fig. IV.7.9). In 2008 there was further decrease of air pollution caused by SO₂ in the whole territory of the CR. In 2009 and 2010, on the contrary, the slight increase of air pollution caused by SO₂ was recorded. From 2011 to 2013 there is another further apparent decreasing trend in air pollution caused by this pollutant.

In 1996–2000 there occurred a marked decrease of SO₂ concentrations (by approx. 70–80 % depending on the respective air pollution characteristic) – Fig. IV.7.10. The development of the trends of SO₂ concentrations is influenced by the decrease of emissions, desulphurisation and the change of the used fuels. To a certain extent there is also the influence of meteorological and dispersion conditions.

The development of SO₂ concentrations with regard to the limit values for the protection of human health

Fig. IV.7.8 shows the apparent decreasing trend in the development of the 4^th highest 24-hour and 25^th highest 1-hour concentrations of SO₂ in selected localities, which started in the year 2003.

In 2013, in comparison with the year 2012, the 4^th highest 24-hour concentration and the 25^th highest 1-hour concentration of SO₂ decreased in almost all localities. This decrease of SO₂ concentrations is apparent at all CHMI stations in the Moravia-Silesia region and the Ústí nad Labem region, where the measurements of SO₂ are carried out in the highest number of localities. The greatest decrease of SO₂ concentrations in comparison with the previous year was recorded at the station Pardubice-Dukla. This locality was influenced by the episode of high 1-hour SO₂ concentrations in March 2012.

The development of SO₂ concentrations with regard to the limit values for the protection of ecosystems and vegetation

The development of the annual and winter average concentrations of SO₂ in selected rural localities is presented in Figs. IV.7.11 and IV.7.12. The annual average of SO₂ concentrations shows an apparent downward trend, the winter average has a slowly decreasing trend as well.

In 2013, as against the previous year, SO₂ annual concentrations decreased in most rural localities. Particularly apparent decrease was recorded at the stations Lom and Věřňovice. As concerns the winter average concentrations of SO₂, the numbers of selected localities with the decrease and the increase of SO₂ concentrations were almost equal. A slight decrease was recorded in the localities in the Moravia-Silesia region and a slight increase was recorded at most stations in the Ústí nad Labem region.

IV.7.3 Emissions of SO₂

Emissions of SO₂ are created mainly during the combustion of sulphur-containing solid fossil fuels. In 2012 the sector of public electricity and heat production contributed by 62.2 % of SO₂ emissions, and the sector of local household heating contributed by 11.7 % (Fig. IV.7.13). The decrease of SO₂ emissions between the years 2007 and 2008 in the sector of public electricity and heat production resulted from the implementation of the obligation to comply with emission ceilings for LCP sources (Fig. IV.7.14). Since 2008 the emissions of SO₂ have remained approximately at the same level. Due to the prevailing influence of the sector of public electricity and heat production SO₂ emissions are concentrated in the Ústí nad Labem region, Moravia-Silesia region and Central Bohemia region, where the largest producers of energy are found (Fig. IV.7.15).

 

Tab. XIII.1 Stations with the highest values of the 25^th and maximum hourly concentrations of SO₂

Tab. XIII.2 Stations with the highest numbers of exceedances of the 24-hour limit value of SO₂

Tab. XIII.17 Stations with the highest values of annual averages of SO₂ concentrations at rural stations

Tab. XIII.18 Stations with the highest values of winter averages of SO₂ concentrations at rural stations, 2013/2014

 

Fig. IV.7.1 Field of the 4^th highest 24-hour concentration of SO₂ in 2013
 

Fig. IV.7.2 Stations with the highest hourly concentrations of SO₂ in 2013
 

Fig. IV.7.3 Stations with the highest 24-hour concentrations of SO₂ in 2013
 

Fig. IV.7.4 Field of annual average concentration of SO₂ in 2013
 

Fig. IV.7.5 Field of average concentration of SO₂ in the winter period 2013/2014
 

Fig. IV.7.6 24-hour concentrations at the stations with the highest annual concentrations of SO2 in 2013
 

Fig. IV.7.7 24-hour concentrations at the stations with the highest winter concentrations of SO₂ in the winter period 2013/2014
 

Fig. IV.7.8 4^th highest 24-hour concentrations and 25^th highest hourly concentrations of SO₂ in 2003–2013 at selected stations
 

Fig. IV.7.9 Trends of SO₂ annual characteristics in the Czech Republic, 1996–2013
 

Fig. IV.7.10 Trends of selected characteristics of SO₂ (index, year 1996 = 100), 1996–2012;
(index, year 2000 = 100), 2000–2013
 

Fig. IV.7.11 Annual average concentrations of SO₂ in 2003–2013 at selected rural stations
 

Fig. IV.7.12 Winter average concentrations of SO₂ in 2003/2004–2013/2014 at selected rural stations
 

Fig. IV.7.13 Emissions of SO₂ sorted out by NFR sectors, 2012
 

Fig. IV.7.14 The development of SO₂ emissions, 2007–2012
 

Fig. IV.7.15 Sulphur dioxide emission density from 5x5 km squares, 2012