The results of long-term measurements show that almost all pollutants measured have a decreasing trend (their concentration is declining in the long run). This decline is generally a result of restructuring the national economy, the modernization of pollutant producing facilities (especially in the sector of industry), and termination or limitation of some production operations. The most significant decrease of emissions in the Czech Republic can be noted in the 1990–2001 period. Further gradual decrease of emissions in 2002–2012 can be attributed to the new legislation implementing a range of European directives. In addition to legal measures, a decline in a number of manufacturing sectors due to the economic crisis was reflected in the decrease of emissions. The emission reduction trend continues in the 2013–2016 period, and other technical measures are in place to reduce emissions in the industry. The Act on protection of the air has also focused on reducing emissions from local heating of households by limiting the production of selected combustion sources between 2014 and 2018 (CHMI, 2016). More detailed information on emissions development are included in publication Air Pollution of Czech Republic in 2019 in chapter II.

Vývoj celkových emisí hlavních znečišťujících látek, 1990–2018 (ČHMÚ 2020).
Vývoj celkových emisí částic, 1990–2018 (ČHMÚ 2020).

Both the local pollution and the long-range transport of polluting substances across borders affect the monitored pollution. The Košetice observatory as a background station in Central Europe is more or less at the average in view of the level of measured pollution.

The concentrations of more or less all monitored air pollutants at our station have been decreasing for a long time and are below the national average in recent years and below the station’s long-term average.

On the contrary, concentrations of ground-level ozone tend to rise, mainly due to higher temperatures, which have an effect on its formation.

The basic characteristics of pollutants (amounts, health and environmental impacts) are given in the publication Air Pollution in the Czech Republic in 2019 in Table I.

CO concentration

CO concentrations in our locality and throughout the country are most affected by the burning of solid fuels for household heating. In the attached graph, we can see the sharp decline that occurred after 2011, when the legislation was also amended. Since the measured concentrations have the greatest influence on the local heating plant, it depends on the amount of solid fuels consumed in a given year.

The lowest average annual concentrations at our station were measured in 2019 and reached the value of 217.8 μg·m–3, on the contrary, the highest value was recorded in 1998 353,5 μg·m–3.

NO2 concentration

NO2 concentrations decrease very slightly, the average annual concentrations fluctuate within the range from 6 μg·m-3 to 12.1 μg·m-3. In 2017, the annual concentration was 6.9 μg·m-3. In 2016, the average concentration of NO2 in the Czech Republic was 18 μg·m-3. In industrial areas in the west of Germany and northern Italy, annual NO2 concentrations exceeding 30 μg·m-3 are measured at many stations.

In Czech Republic, NOconcentrations are most influenced by transport, agricultural production and local heating plants, and the values are identical to other rural-type stations. Throughout the country, the highest concentrations are measured in places that are burdened by traffic (cities, highways) and heavy indust

 The lowest average annual concentration of 3.1 μg·m–3 at our station was measured in 2020, while the highest value was recorded in 1996, 12,1 μg·m–3.

In the European context, the situation is similar to that in the Czech Republic. Areas of large agglomerations, industrial areas and main traffic arteries are the most polluted.

Ground ozon (O3)

O3 concentrations are at a stable level throughout the measurement period. The highest concentrations were measured in years that were exceptionally above average in terms of temperature and strongly below average in terms of precipitation.


The results of the annual averages show that the values from our station are significantly higher than the national average. However, such high values are characteristic for this type of rural stations. On the contrary, lower concentration values are recorded at urban stations, where, due to traffic emissions, chemical reactions other than the formation of ground-level ozone are favored.

The lowest average annual concentrations at our station were measured in 2014 and reached the value of 57.0 μg·m–3, on the contrary, the highest value was recorded in 2003 72,6 μg·m–3.

Comparing the values Within Europe, the concentrations of O3 (regarding the mechanism of its formation) increase from low values in Northern Europe to the highest concentrations, especially in the states around the Mediterranean Sea. In that matter, the Czech Republic is among the average to above average polluted areas.

Particles PM10 and PM2,5

Concentrations of PM10 aerosol particles decreased from 29.4 μg·m-3 (in 1996) to 16.4 μg·m-3 (in 2017). In spite of the long-term decreasing trend, concentrations in the monitored period increased after 2001. This increase was the result of unfavourable meteorological conditions and it was reflected in the measurements of all stations in the Czech Republic. Average concentrations of PM10 in the Czech Republic were 25 μg·m-3 in 2016, concentrations at rural stations slightly exceeded 20 μg·m-3. Most stations in Europe registered concentrations less than 30 μg·m-3 in 2015, except for stations in Poland, northern Italy and Bulgaria, where concentrations exceeded both the value of 30 μg·m-3 and also the limit level, i.e. 40 μg·m-3 at an annual average

Concentration of SO2

SO2 concentrations decreased from an average annual value of 14.5 μg·m-3 in 1985 to 2.2 μg·m-3 in 2017. However, the highest annual concentrations of 27.8 μg·m-3 was registered in 1991. The average SO2 concentrations in the Czech Republic were less than 6 μg·m-3 in 2016, the concentration at rural stations slightly exceeded 4 μg·m-3.

The situation with SO2 concentrations in the context of Europe is not significantly different from the Czech Republic, and the situation with the development of concentrations of this substance is managed to be regulated thanks to legislation. The problem with higher concentrations remains only in the eastern part of Europe.

Source: Internal documentation of CHMI, 2020. Air Pollution in Czech Republic in 2019, Prague, ISBN 978-80-7653-009-6.