II.4 Air quality assessment

The extent of air pollution is objectively determined by monitoring the concentrations of ambient air pollutants (air quality monitoring) in the ground layer of atmosphere within the network of measuring stations. Within air quality assessment there are compared mainly the recorded levels of air pollution concentrations with the respective limit values and target values, or with admissible exceedance frequencies of these limits, i.e. air pollution levels which should not be exceeded after the date set by the valid air quality legislation.

The Yearbook presents air quality assessment in the year 2011 with regard to the requirements of the Czech legislation on air quality protection. Pursuant to the Clean Air Act the assessment is aimed at defining the areas with exceedances of the limit values and the target values, both for the protection of health and the protection of vegetation and ecosystems, and mainly at defining the areas with deteriorated air quality, with regard to the protection of human health.

Air quality assessment pursuant to the valid legislation reassumes the results and methods developed within the two research projects solved by CHMI, and namely VaV/740/2/00 �Evaluation of the Czech Republic Readiness to Meet Air Quality Requirements of EU Directives and the LRTAP Convention� [9], and VaV/740/3/02 �Integrated air quality assessment and management with regard to the daughter directives on heavy metals, PAH, PM10 and benzene� [23].

The EU air quality directives on which the Czech legislation is based require that the member states should divide their territories into zones and agglomerations while the zones and agglomerations are understood as basic units for air quality management. The directives specify namely the requirements for the assessment – the classification of the zones with regard to air quality. The Clean Air Act (No. 86/2002 Coll.), as amended, covers this issue in par. 7 dealing with special air quality protection. Article 1 introduces the term �area of deteriorated air quality� for the area within the zone or agglomeration, where the level of the respective air pollution limit value is exceeded in one or more pollutants.

The zone is a part of the territory delimited by the Ministry of Environment for the monitoring and management of air quality, and the agglomeration is a residential area where the population concentration is at least 350,000 inhabitants, delimited by the Ministry for the monitoring and management of air quality. Three agglomerations were defined; the Capital City of Prague and the city of Brno agglomerations represent the areas where ambient air pollution is connected mainly with high density of population, in the Moravian-Silesian Region agglomeration (covering i.a. the cities of Ostrava, Karviná, Havířov, Český Těšín and Třinec) air pollution is influenced, besides population density, also by high concentration of industrial plants. Due to the delineation of agglomerations air quality assessment in these areas will be determined mainly on the basis of regular measurements of good quality. Other regions of the Czech Republic were defined as zones (including the South-Moravian Region without the territory of the city of Brno).

In addition to agglomerations, the Yearbook deals in great detail with the zone Ústí nad Labem Region, where, similarly as in the Moravian-Silesian agglomeration, both the population density and industry concentration are higher. For the first time the detailed assessment was carried out for the areas of the Hradec Králové Region and the Pardubice Region.

In the areas not included into the category of deteriorated air quality, i.e. in the areas where no limit values are exceeded, it is necessary to ensure the maintenance of good air quality. This corresponds with one of the basic principles of the Directive 2008/50/EC. Where the objectives for ambient air quality laid down in this Directive are not met, Member States should take action in order to comply with the limit values and to attain the target values and long-term objectives.

In the areas with deteriorated air quality the Clean Air Act (No. 86/2002 Coll.), as amended, in its Article 6, par. 7 sets the obligation for the regional and local authorities of municipalities with population above 350,000 to develop programmes aimed at the improvement of air quality for those pollutants which showed in the previous year the exceedances of the limit values. The aim of the programmes is to reduce ambient air pollution below the limit values in the deadlines set in the implementing regulations.

The term �hot spot� is used in the assessment, generally for localities with high level of ambient air pollution. In our assessment, however, this term refers to the stations oriented exclusively to traffic and to the resulting increased air pollution loads. The monitoring stations classified as hot spots are operated by CHMI in the localities with heavy traffic loads in Prague, Brno, Ostrava and Ústí nad Labem. These localities meet the criteria for the location of traffic-oriented samplers pursuant to the Government Order No. 597/2006 Coll., as amended.

The air quality assessment is documented by the tables showing the localities with the highest values of air pollution characteristics set by the Czech legislation. The shades of the background in the tables indicate:

All tables for individual pollutants present at least 10 stations with the highest values of the respective air pollution characteristic in the given year. The maps depict clearly the development of the respective characteristics in the period 2001–2011. The 2011 exceedance of the limit value (target value) is highlighted with red names of the stations in the maps.

Further, maps depicting the spatial distribution of air pollution characteristic are presented. These maps show also the measuring stations marked with different symbols and colours according to their type and category of the level of the respective air pollution characteristic measured at the presented station. The intervals of the classes in the legend are based on the lower and upper assessment thresholds and on the limit (target) value for individual substances. The exceedance of the limit value, or the target value, is marked with red colour.

For the stations and air pollution characteristics, where the number of exceedances of the limit value was higher than it is allowed, the courses of 24-hour or hourly concentrations in 2011 are presented for the indication of the period of the year during which the limit values were exceeded.
The courses of air pollution caused by individual pollutants at selected stations during the year 2011 are documented by the graphs.

The Yearbook includes the graphs showing the trends of the characteristics of selected pollutants in agglomerations and in the whole territory of the Czech Republic starting from the year 1996. The values depicted in the graphs are calculated as total average from average concentrations only of those monitoring stations in the given territory which measured the monitored pollutant for the whole evaluated period.