Graphic Yearbook 2015
IV.5 BENZENE
IV.5.1 Air pollution caused by benzene in the
year 2015
The ambient limit value for benzene (C6H6) of 5 μg.m-3 was not exceeded at any of the 30 localities monitored in 2015 (Fig. IV.5.1). The highest concentrations were reached, as in previous years, at stations in the O/K/F-M agglomeration. The stations most exposed to benyene were Ostrava-Přívoz and Ostrava-Radvanice ZÚ (Table XIII.13). At the Ostrava-Přívoz station, the annual average concentration increased compared to 2014 from 3.1 µg.m-3 to 5.0 µg.m-3 because, as prior to 2013, high peak hourly and daily concentrations on the order of tens of µg.m-3 were more frequent. At the locality Ostrava-Radvanice ZÚ, concentrations decreased imperceptibly from 3.6 µg.m-3 to 3.5 µg.m-3. There were decreases at five out of the eight monitored localities within the O/K/F-M agglomeration. The higher concentrations of C6H6 in the O/K/F-M agglomeration are connected primarily with industrial activities, namely with coke production and processing of chemical products (Fig. IV.5.1, Fig. IV.5.3; CHMI 2013b).
In comparison with the year 2014, approximately 60 % of localities (15 localities) recorded decreased annual average concentration of benzene, while 28 % of localities (7 localities) recorded increases of these concentrations (of the total number of 25 stations which measured benzene concentrations both in 2014 and 2015). In the summer period, benzene concentrations are usually lower than those in the winter period. This annual course is probably the result of worsened dispersion conditions in winter periods (Schnitzhofer et al. 2008).
IV.5.2 Development of benzene concentrations
The annual average concentration of benzene in the Czech Republic within the period of 2005–2015 reached its maximum levels in the year 2006. Since then the concentration has been gradually decreasing with one positive deviation in the year 2010. The years 2006 and 2010 were characterized by deteriorated dispersion conditions in the Czech Republic, which could result in the increased accumulation of pollutants in the air (Fig. IV.5.4). In 2015 the annual average concentration incereased marginally compared to the year 2014. This was caused by an increase of concentrations at industrial localities. At localities of other types, concentrations decreased.
Higher annual average concentrations are measured at urban localities; the highest benzene concentrations are usually reached at stations classified as urban industrial and urban traffic localities. Rural localities, by contrast, reach the lowest values (Fig. IV.5.4). The same results have been reported by Karakitsios et al. (2007). The reason is the concentration of industrial production and road transport in urban areas.
Benzene reaches its highest annual average concentrations in the O/K/F-M agglomeration (Fig. IV.5.1, Fig. IV.5.2). Yet, the results of long-term automated measurements in this area show that the annual average concentrations of benzene have had a downward trend there since 2012, with the exception of the Ostrava-Přívoz station in 2015. Exceedances of the annual limit value at the station Ostrava- Přívoz before the year 2013 occurred due to the fact that this locality recorded 1-hour concentrations greater than 50 µg.m-3, i.e. concentrations which at other stations in Ostrava occurred in much smaller numbers and which did not occur at all outside Ostrava. Benzene concentrations in Ostrava were temporarily influenced also by the removal of old ecological burdens in Ostrava-Mariánské Hory in 20111. The annual concentrations decreased after the shutdown of the coke plant Koksovny Jan Šverma (shut down on 31 December 2010) and after the implementation of a number or measures aimed at reducing emissions from sources of the companies BorsodChem MCHZ, s. r. o. and OKK koksovny, a. s. (CHMI 2013b).
IV.5.3 Emissions of benzene
The balance of benzene emissions is based for the most part on calculations made from reported VOC emissions. Reported emissions can be found only for the sources which are legally obliged to ascertain air pollution levels, mainly for the verification of their compliance with the emission limit values. There are certain exceptions, such as coke plants and associated branches of chemical production, for which their operators are obliged to ascertain benzene emissions pursuant to the integrated permit, and specific procedures are used to ascertain the release. The agglomeration of O/K/F-M, where such technologies are used, had for a long time been one of the few areas where the set limit values were exceeded.
In the past years, emission balances for benzene were produced only exceptionally, usually as part of certain projects. The last of them presents data for the year 2010, and the greatest share of the total amount of benzene (approx. 1,250 t.year-1) is represented by the use of paints (Resler, Jareš 2014). The shares of benzene in VOC emissions result partly from the composition of the products used (e.g. solvents, paints, finishes and adhesives), from different types of fuels, or they are determined from the assumed composition of specific organic substances formed during the combustion of various types of fuels. The greatest amount of benzene emissions for the year 2014 (as well as for the previous one) was reported by the chemical production company DEZA, a. s. – Chemické výroby, Valašské Meziříčí (3.297 t.year-1); emissions from other sources are lower by an order of magnitude.
Tab. XIII.13 Stations with the highest values of annual average
concentrations of benzene
Fig. IV.5.1 Field of annual average concentration of benzene,
2015
Fig. IV.5.2 Annual average concentrations of benzene at selected
stations, 2005–2015
Fig. IV.5.3 Five-year average of annual average concentrations
of benzene, 2011–2015
Fig. IV.5.4 Trends of benzene annual characteristics in the
Czech Republic, 2005–2015
1Removal of old ecological burdens in Ostrava-Mariánské Hory was carried out in 2011 by remediation of waste lagoons formed by waste disposal from refinery production launched at the end of the 19th century (from 1965 onwards, waste from the regeneration of lubricating oils was also deposited there by the state enterprise OSTRAMO Ostrava, succeeded in 1992 by OSTRAMO-Vlček and co., s. r. o.). The plant was shut down in 1996.
