IV.7 SULPHUR DIOXIDE
 

IV.7.1 Air pollution caused by sulphur dioxide in the year 2015
 

Air pollution caused by sulphur dioxide in the year 2015 with regard to the limit values for the protection of human health

In 2015 neither the limit value for the hourly sulphur dioxide (SO₂) concentration nor for the 24-hour SO₂ concentration was exceeded in the Czech Republic at any monitoring station (Tables XIII.18 and XIII.19). Four stations detected 1-hour concentrations of SO₂ exceeding the limit value of 350 μg.m^-3; however, the permissible number of exceedances of 24 was not overstepped (Měděnec, Nová Víska u Domašína and Lom in the Ústí nad Labem region, and Dolní Rychnov in the Karlovy Vary region). It can be assumed that measurements at these stations are influenced by important energy and industrial sources located in the Podkrušnohorská basin and the Sokolov basin.

The highest 1-hour concentrations of SO₂ were detected at the Měděnec station, where four exceedances of the limit value occurred over the course of the year in night or morning values of 2 November 2015. Concentrations of SO₂ reached values of 360 to 666 μg.m-3. Three exceedances of the ambient limit occurred at the locality Nová Víska u Domašína (471 μg.m^-3, 452 μg.m^-3 and 376 μg.m^-3). These episodes in which limit values for SO₂ were exceeded were at both localities probably caused by the impact of a smoke plume from the Prunéřov power plant. This is supported by the fact that only a weak easterly wind blew during the mentioned episodes. Hourly limit-exceeding concentrations of SO₂ were also detected at the stations Lom (395 μg.m^-3) and Dolní Rychnov (357 μg.m^-3). The increase in hourly concentrations of SO₂ at the station Lom on 6 November 2015 led to the announcement of a smog situation (for details, see Chapter VI.).

The 25th highest SO₂ concentration reached its maximum values at the stations Lom (133 μg.m^-3), Ostrava-Radvanice ZÚ (135 μg.m^-3), Krupka (120 μg.m^-3) and Dolní Rychnov (130 μg.m^-3). The maximum 24-hour concentrations of SO₂ did not exceed the limit value of 125 μg.m^-3 (e.g. Ostrava- Radvanice ZÚ 108 μg.m^-3, Krupka 105 μg.m^-3, Měděnec 98 μg.m^-3). The 4th highest 24-hour SO₂ concentration reached its maximum values at the stations Ostrava-Radvanice ZÚ 82 μg.m^-3, Krupka (61 μg.m^-3) and Petrovice u Karviné (59 μg.m^-3). In 99.9 % of the Czech Republic territory, 24-hour concentrations of SO₂ were below the lower assessment threshold (LAT). Only in 0.1 % of the Czech Republic territory concentrations exceeded the LAT, mainly in the Ústí nad Labem region, in part of the Podkrušnohorská basin in the Most district and the Teplice district (Fig. IV.7.1).

Considering the decrease in concentrations between 2014 and 2015, most of the area of the Czech Republic (63.5 %) is not exposed to SO₂ concentrations exceeding the WHO guideline limit for the pro- tection of human health. In other words, the 24-hour average concentration of 20 μg.m^-3 was not exceeded on 63.5 % of the country’s territory in 2015.

 
Air pollution in 2015 by sulphur dioxide with regard to limit values for the protection of ecosystems and vegetation

In 2015 neither the limit value for the annual average concentration nor the limit value for the winter average concentration was exceeded at rural locali- ties (Tables XIII.21 and XIII.22). The highest winter average concentration in 2015 was recorded at the localities Krupka (13.2 µg.m^-3), Sněžník (10.4 µg.m^-3), Lom (9.9 µg.m^-3) and Věřňovice (9.3 µg.m^-3). The annual average concentration reached its maxi- mum at the localities Horní Lomná (15.5 µg.m^-3), Krupka (10.3 µg.m^-3) and Lom (9.1 µg.m^-3). However, the station Horní Lomná was placed next to a secondary residence, which might have interfered with the measurements.

In 2015 the upper assessment threshold (UAT) for annual average concentrations of SO₂ was exceeded only in small parts of the Ústí nad Labem region, the Karlovy Vary region, the Moravia-Silesia region and the Olomouc region (Fig. IV.7.5). Also exceeded in the same areas (except from the Olomouc region) was the UAT for average concentrations for the winter period 2015/2016 (Fig. IV.7.6).

Both maps (Fig. IV.7.5 and Fig. Fig. IV.7.6) were constructed using data from all background stations measuring SO₂, with regard to their classification. Point marks on the maps indicate only rural stations because winter and annual average concentrations of SO₂ are assessed at these localities only, also due to the ambient limit for the protection of ecosystems and vegetation.

IV.7.2 Development of sulphur dioxide concentrations

There was a marked decrease of ambient SO₂ concentrations after the year 1998 in connection with the coming into force of Act No. 309/1991 Coll. and the meeting of required emission limit values. Since then, the annual average concentrations of this pollutant have not exceeded the set limit value of 20 μg.m^-3 at rural stations. In 2008 there was a further decrease of air pollution caused by SO₂ in the whole territory of the Czech Republic. In 2009 and 2010, on the contrary, a slight increase of air pollution caused by SO₂ was recorded. From 2011 to 2015, a further decreasing trend is apparent (Fig. IV.7.3).

In 2000–2015 there was an overall decrease of SO₂ concentrations (by approx. 30–50 % depending on the respective air pollution characteristic; Fig. IV.7.4).

The trend of SO₂ concentrations is caused by a decrease of emissions, desulphurisation of coal-fired power plants and a change in the fuels used (see the trends in the development of emissions in Chapter II). Year-to-year fluctuations of concentrations are also influenced by differing meteorological conditions in particular years.

Development of sulphur dioxide concentrations with regard to the limit values for the protection of human health

Since 2005 there is an apparent decreasing trend in the development of the 4^th highest 24-hour and 25^th highest 1-hour concentrations of SO₂ at selected localities (Fig. IV.7.2). In 2015, compared to the year 2014, these values decreased at most localities. A decrease of SO₂ concentrations in comparison with the previous year was recorded, for example, at the stations Studénka, Sokolov and Teplice. Conversely, a rise in concentrations of SO₂ occurred at the stations Krupka, Výslunní and Zlín-Svit.

Development of sulphur dioxide concentrations with regard to the limit values for the protection of ecosystems and vegetation

Both the annual and the winter average of SO₂ concentrations at rural stations show an apparent gradual downward trend (IV.7.7 and IV.7.8). In 2015, as against the previous year, annual as well as winter concentrations of SO₂ decreased at most rural localities. A particularly apparent decrease was recorded at the stations Lom, Měděnec and Studénka. Conversely, an increase of SO₂ concentrations is observable at the stations Krupka and Churáňov.

IV.7.3 Emissions of sulphur dioxide

Emissions of SO₂ are created mainly during the combustion of sulphur-containing solid fossil fuels. In 2014, 63.6 % of SO₂ emissions on the countrywide scale came from sector 1A1a-Public electricity and heat production, and 10.7 % were contributed by sector 1A4bi-Residential stationary combustion contributed (Fig. IV.7.9). The decrease of SO₂ emissions between the years 2007 and 2008 in sector 1A1a-Public electricity and heat production resulted from the implementation of the obligation to comply with emission ceilings for LCP sources (Fig. IV.7.10). Since 2008 the emissions of SO₂ have remained approximately at the same level, with a more pronounced decrease between the years 2012 and 2013. Due to the prevailing influence of the public electricity and heat production sector, SO₂ emissions are concentrated in the Ústí nad Labem region, the Moravia-Silesia region and the Central Bohemia region, where the largest producers of energy are located (Fig. IV.7.11).

Tab. XIII.18 Stations with the highest values of the 25^th and maximum hourly concentrations of SO₂

Tab. XIII.19 Stations with the highest numbers of exceedances of the 24-hour limit value of SO₂

Tab. XIII.20 Stations with the highest values of annual average concentrations of SO₂

Tab. XIII.21 Stations with the highest values of annual averages of SO₂ concentrations at rural stations

Tab. XIII.22 Stations with the highest values of winter averages of SO₂ concentrations at rural stations, 2015/2016

 

Fig. IV.7.1 Field of the 4^th highest 24-hour concentration of SO₂, 2015

Fig. IV.7.2 4^th highest 24-hour concentrations and 25^th highest hourly concentrations of SO₂ at selected stations, 2005–2015

Fig. IV.7.3 Trends of SO₂ annual characteristics in the Czech Republic, 2000–2015

Fig. IV.7.4 Trends of selected characteristics of SO₂ (index, year 2000 = 100), 2000–2015

Fig. IV.7.5 Field of annual average concentration of SO₂, 2015

Fig. IV.7.6 Field of average concentration of SO₂ in the winter period 2015/2016

Fig. IV.7.7 Annual average concentrations of SO₂ at selected rural stations, 2005–2015

Fig. IV.7.8 Winter average concentrations of SO₂ at selected rural stations, 2005/2006–2015/2016

Fig. IV.7.9 Total emissions of SO₂ sorted out by NFR sectors, 2014

Fig. IV.7.10 The development of SO₂ total emissions, 2007–2014

Fig. IV.7.11 Sulphur dioxide emission density from 5x5 km squares, 2014