In accordance with Annex 2 of Decree 106/2025, which implements certain provisions of the Act on the Public Hydrometeorological Service, the Czech Hydrometeorological Institute (CHMI) provides current operational (unverified) hourly data on outdoor air pollutants (pollutant concentrations from monitoring stations with automated measurement programs, as specified by Act No. 201/2012 Coll., on Air Protection).
The data made available include key pollutants with ambient air quality limits under current legislation: nitrogen dioxide (NO₂), nitrogen oxides (NOₓ), ground-level ozone (O₃), suspended particles PM₁₀ and PM₂.₅, sulfur dioxide (SO₂), and carbon monoxide (CO).
The data are based on measurements taken at stations owned by CHMI.
In accordance with Annex 2 of Decree 106/2025 Coll., which implements certain provisions of the Act on the Public Hydrometeorological Service, the Czech Hydrometeorological Institute (CHMI) has made operational (unverified) primary and aggregated data available for outdoor air pollutants (pollutant concentrations from automatic monitoring stations, provided in the scope and temporal aggregations specified by Act No. 201/2012 Coll., on Air Protection).
The data include key pollutants with ambient air limit values under current legislation: arsenic (As), benzene, benzo[a]pyrene, cadmium (Cd), carbon monoxide (CO), nickel (Ni), nitrogen dioxide (NO₂), nitrogen oxides (NOₓ), ground-level ozone (O₃), lead (Pb), suspended particles PM₁₀, suspended particles PM₂.₅, and sulfur dioxide (SO₂).
The data are based on measurements from CHMI-owned stations since 1969. Primary data are provided in measurement intervals of 30 minutes, 1 hour, or 24 hours, depending on the type of measurement. Aggregated data are calculated from the aforementioned primary data and include the following: daily averages, monthly averages, annual averages, and the number of exceedances of ambient air limit values. Preliminary data include air quality information that is older than one hour. Verified data can be found in the dataset *Air Quality Measurements – Verified Data*, in accordance with the data verification process. Verification is carried out once a year, no later than July 1st (YYYY-1).
In accordance with Annex 2 of Decree 106/2025 Coll., which implements certain provisions of the Act on the Public Hydrometeorological Service, the Czech Hydrometeorological Institute (CHMI) provides current operational (unverified) hourly data on the Air Quality Index.
The Air Quality Index (IKO) provides a summary of air quality at a specific monitoring station. This index was developed by the Air Quality Division of the Czech Hydrometeorological Institute (ČHMÚ) in collaboration with the National Institute of Public Health (SZÚ). Specific advice and recommendations from SZÚ aimed at protecting human health can be found here: www.chmi.cz/files/portal/docs/uoco/web_generator/d_szu.pdf. The rules for determining the IKO and its calculation are available at https://www.chmi.cz/files/portal/docs/uoco/web_generator/iko3h_cz.pdf.
Information for the public provided through a simple and comprehensible indicator that comprehensively reflects air quality, considering health-based recommendations from the World Health Organization.
In accordance with Annex 2 of Decree 106/2025 Coll., which implements certain provisions of the Act on the Public Hydrometeorological Service, the Czech Hydrometeorological Institute (CHMI) provides operational (unverified) hourly data on the Air Quality Index. The Air Quality Index (IKO) provides a summary of air quality at a specific monitoring station. This index was developed by the Air Quality Division of the Czech Hydrometeorological Institute (ČHMÚ) in collaboration with the National Institute of Public Health (SZÚ). Specific advice and recommendations from SZÚ aimed at protecting human health can be found here: www.chmi.cz/files/portal/docs/uoco/web_generator/d_szu.pdf. The rules for determining the IKO and its calculation are available at https://www.chmi.cz/files/portal/docs/uoco/web_generator/iko3h_cz.pdf.
Information for the public provided through a simple and comprehensible indicator that comprehensively reflects air quality, considering health-based recommendations from the World Health Organization.
In accordance with Annex 2 of Decree 106/2025 Coll., which implements certain provisions of the Act on the Public Hydrometeorological Service, the Czech Hydrometeorological Institute (CHMI) has made verified primary and aggregated data available for outdoor air pollutants (pollutant concentrations from Concentration of pollutants from monitoring stations with automatic and manual programs, provided in the scope and temporal aggregations specified by Act No. 201/2012 Coll., on Air Protection).
The data include key pollutants with ambient air limit values under current legislation: arsenic (As), benzene, benzo[a]pyrene, cadmium (Cd), carbon monoxide (CO), nickel (Ni), nitrogen dioxide (NO₂), nitrogen oxides (NOx), ground-level ozone (O₃), lead (Pb), suspended particles PM10, suspended particles PM2.5, and sulfur dioxide (SO₂).
The data are based on measurements from CHMI-owned stations since 1969. Primary data are provided in measurement intervals of 30 minutes, 1 hour, or 24 hours, depending on the type of measurement. Aggregated data are calculated from the aforementioned primary data and include the following: daily averages, monthly averages, annual averages, and the number of exceedances of ambient air limit values.
The most recent verified data available date back approximately 18 months from the current date, in accordance with the data verification process.
Concentrations of air pollutants in the 1x1 km grid, years 2018–2023. Limit values for the protection of human health SO2 - 4th highest 24-hour SO2 concentration [µg.m-3], PM10 - annual average concentration [µg.m-3], PM10 - 36th highest 24-hour average concentration [µg.m-3], PM2.5 - annual average concentration [µg. m-3], NO2 - annual average concentration [µg.m-3], O3 - 26th highest maximum daily 8-hour moving average concentration averaged over 3 years, 2019-2021 [µg.m-3], As - annual average concentration [ng.m-3], Cd - annual average concentration [ng.m-3], benzo[a]pyrene - annual average concentration [ng.m-3], benzene - annual average concentration [µg.m-3]. Areas with exceedances of limit values without O3. Areas with exceedances of the limit values with the inclusion of O3. Limit values for the protection of ecosystems and vegetation O3 - AOT40 exposure index values, 5-year average, 2019-2023 [µg.m-3], NOx - annual average concentration [µg.m-3], SO2 - annual (annual average) and winter period (winter average) [µg.m-3].
Legislation (Act 201/2012 Coll., as amended) requires that the primary source of assessment be the results of stationary measurements. Measured concentrations may be supplemented by modelling and indicative measurements in the production of pollutant maps to ensure that the resulting estimate provides sufficient information on the spatial distribution of air pollutant concentrations. In the Czech Republic, the Eulerian chemical dispersion model CAMx is mainly used, additionally also the Gaussian model SYMOS and the European Eulerian model EMEP. In addition, in the case of individual pollutants, e.g. altitude or population density.
Act No. 201/2012 Coll., on Air Protection, as amended
In accordance with Annex 2 of Decree 106/2025 Coll., which implements certain provisions of the Act on the Public Hydrometeorological Service, the Czech Hydrometeorological Institute (CHMI) provides yearbooks. The Yearbook “Air Pollution in the Czech Republic in the YYYY,” together with the published data yearbook “Summary Tabular Overview” and the methodological material “Data Collection, Processing, and Evaluation System,” provides a complete overview of air quality information in the Czech Republic for the given year. The air quality assessment is based on measured data collected within the ISKO framework, utilizing additional resources and mathematical tools. The data yearbook presents verified measured concentration data and information on the chemical composition of atmospheric precipitation from various locations, including aggregated data. The graphical yearbook offers summarized information with commentary in the form of detailed maps, graphs, and tables.
In accordance with Annex 2 of Decree 106/2025 Coll., which implements certain provisions of the Act on the Public Hydrometeorological Service, the Czech Hydrometeorological Institute (CHMI) provides data (tabular) yearbooks. The summary annual tabular survey “Air Pollution and Atmospheric Deposition in Data, the Czech Republic...” (hereinafter referred to as the Tabular Survey) is published as a basic overview of measured pollutant concentrations in ambient air in the Czech Republic for the given calendar year. It is primarily intended for use by state administration authorities and organizations dealing with environmental issues and air quality protection in the Czech Republic.
Concentrations measured by all monitoring networks are stored in the AQIS air pollution database. The database contains data from the beginning of measurements, and sulphur dioxide and suspended particulate matter concentrations from the station networks of the CHMI in North Bohemia and Prague from 1971. Accompanying meteorological data, which are measured at a large part of the automated monitoring stations of the CHMI are used for the evaluation of air quality-meteorological relationships, are also stored in the ISKO database. In addition, the ISKO emission database also includes data provided by cooperating institutions. These include the Public Health Institute in Ostrava, the Public Health Institute in Ústí nad Labem, the National Institute of Health, ČEZ, a. s., municipal authorities and other contributors. The database also includes information from the border areas of Slovakia, Germany, Poland and Austria.
Overview of concentrations of air pollutants for which limit values for the protection of human health have been set, measured at station networks of ambient air quality monitoring in the Czech Republic: r18–r23As - List of stations with annual average concentrations of As, 2018–2023; r18–r23BaP - List of stations with annual average concentrations of benzo[a]pyrene, 2018–2023; r18–r23BZN – List of stations with annual average concentrations of benzene, 2018–2023; r18–r23Cd – List of stations with annual average concentrations of cadmium, 2018–2023; r18–r23NO2 – List of stations with concentrations of NO2 (annual average and 19. highest hourly concentrations), 2018–2023; r18–r23O3 – List of stations with ground-level ozone concentrations (max. daily 8-hour moving average, averaged over 3 years), 2018–2023; r18–r23PM10 – List of stations with PM10 concentrations (annual mean and 36. highest 24-hour concentrations), 2018–2023; r18–r23PM25 – List of stations with PM2.5 annual average concentrations, 2018–2023; r18–r23SO2zdr – List of stations with SO2 concentrations (25th highest hourly concentrations and 4th highest 24-hour concentrations), 2018–2023. Summary of concentrations of air pollutants for which immission limits are set to protect ecosystems and vegetation, measured at station networks of ambient air quality monitoring in the Czech Republic: r18–r23AOT40 – AOT40 exposure index values, 5-year average, 2018–2023 [µg. m-3.h]; r18–r23NOx – List of stations with annual average NOx concentrations, 2018–2023; r18–r23SO2zp – List of stations with SO2 concentrations (winter average), 2018–2023; r18–r23SO2rp – List of stations with annual average SO2 concentrations, 2018–2023.
Pollutants with air quality limits set for health protection with an averaging period of 1 calendar year:
NO₂_rp_5l: NO₂ – annual average concentration [µg·m⁻³], PM₁₀_rp_5l: PM₁₀ – annual average concentration [µg·m⁻³], PM₂₅_rp_5l: PM₂.₅ – annual average concentration [µg·m⁻³], BZN_rp_5l: benzene – annual average concentration [µg·m⁻³], BaP_rp_5l: benzo[a]pyrene – annual average concentration [ng·m⁻³], As_rp_5l: arsenic – annual average concentration [ng·m⁻³], Pb_rp_5l: lead – annual average concentration [ng·m⁻³], Ni_rp_5l: nickel – annual average concentration [ng·m⁻³], Cd_rp_5l: cadmium – annual average concentration [ng·m⁻³].
Pollutants with air quality limits set for health protection with an averaging period of 24 hours:
PM₁₀h24_5l: PM₁₀ – 36th highest 24-hour average concentration in a calendar year [µg·m⁻³],
SO₂h24_5l: SO₂ – 4th highest 24-hour average concentration in a calendar year [µg·m⁻³].
Pollutants with air quality limits set for the protection of ecosystems and vegetation:
SO₂_rp_5l: SO₂ – annual average concentration [µg·m⁻³],
SO₂_zp_5l: SO₂ – average concentration for the winter period (1.10.–31.3.) [µg·m⁻³],
NOₓ_rp_5l: NOₓ – annual average concentration [µg·m⁻³].
Concentrations of air pollutants in the 1x1 km grid, year 2024. Limit values for the protection of human health SO2 - 4th highest 24-hour SO2 concentration [µg.m-3], PM10 - annual average concentration [µg.m-3], PM10 - 36th highest 24-hour average concentration [µg.m-3], PM2.5 - annual average concentration [µg. m-3], NO2 - annual average concentration [µg.m-3], O3 - 26th highest maximum daily 8-hour moving average concentration averaged over 3 years, 2022-2024 [µg.m-3], As - annual average concentration [ng.m-3], Cd - annual average concentration [ng.m-3], benzo[a]pyrene - annual average concentration [ng.m-3], benzene - annual average concentration [µg.m-3]. Areas with exceedances of limit values without O3. Areas with exceedances of the limit values with the inclusion of O3. Limit values for the protection of ecosystems and vegetation O3 - AOT40 exposure index values, 5-year average, 2020-2024 [µg.m-3], NOx - annual average concentration [µg.m-3], SO2 - annual (annual average) and winter period (winter average) [µg.m-3].
Legislation (Act 201/2012 Coll., as amended) requires that the primary source of assessment be the results of stationary measurements. Measured concentrations may be supplemented by modelling and indicative measurements in the production of pollutant maps to ensure that the resulting estimate provides sufficient information on the spatial distribution of air pollutant concentrations. In the Czech Republic, the Eulerian chemical dispersion model CAMx is mainly used, additionally also the Gaussian model SYMOS and the European Eulerian model EMEP. In addition, in the case of individual pollutants, e.g. altitude or population density.
Act No. 201/2012 Coll., on Air Protection, as amended
Concentrations measured by all monitoring networks are stored in the AQIS air pollution database. The database contains data from the beginning of measurements, and sulphur dioxide and suspended particulate matter concentrations from the station networks of the CHMI in North Bohemia and Prague from 1971. Accompanying meteorological data, which are measured at a large part of the automated monitoring stations of the CHMI are used for the evaluation of air quality-meteorological relationships, are also stored in the ISKO database. In addition, the ISKO emission database also includes data provided by cooperating institutions. These include the Public Health Institute in Ostrava, the Public Health Institute in Ústí nad Labem, the National Institute of Health, ČEZ, a. s., municipal authorities and other contributors. The database also includes information from the border areas of Slovakia, Germany, Poland and Austria.
Overview of concentrations of air pollutants for which limit values for the protection of human health have been set, measured at station networks of ambient air quality monitoring in the Czech Republic: r24As - List of stations with annual average concentrations of As, 2024; r24BaP - List of stations with annual average concentrations of benzo[a]pyrene, 2024; r24BZN – List of stations with annual average concentrations of benzene, 2024; r24Cd – List of stations with annual average concentrations of cadmium, 2024; r24NO2 – List of stations with concentrations of NO2 (annual average and 19. highest hourly concentrations), 2024; r24O3 – List of stations with ground-level ozone concentrations (max. daily 8-hour moving average, averaged over 3 years), 2024; r24PM10 – List of stations with PM10 concentrations (annual mean and 36. highest 24-hour concentrations), 2024; r24PM25 – List of stations with PM2.5 annual average concentrations, 2024; r24SO2zdr – List of stations with SO2 concentrations (25th highest hourly concentrations and 4th highest 24-hour concentrations), 2024. Summary of concentrations of air pollutants for which immission limits are set to protect ecosystems and vegetation, measured at station networks of ambient air quality monitoring in the Czech Republic: r24AOT40 – AOT40 exposure index values, 5-year average, 2024 [µg. m-3.h]; r24NOx – List of stations with annual average NOx concentrations, 2024; r24SO2zp – List of stations with SO2 concentrations (winter average), 2024; r24SO2rp – List of stations with annual average SO2 concentrations, 2024.
In accordance with Annex 2 of Decree No. 106/2025 Coll., implementing certain provisions of the Act on Public Hydrometeorological Service, the Czech Hydrometeorological Institute (CHMI) provides access to monthly reports assessing air quality. The Air Quality Division of the Czech Hydrometeorological Institute (CHMI) has been issuing reports from October 2014 to the end of 2023, evaluating air pollution and dispersion conditions in the Czech Republic for the preceding month. The aim of these reports is to provide the public with the most up-to-date information and assessments of the situation.
The evaluation primarily relies on measured concentrations of suspended particulate matter (PM10), which represents one of the major air quality issues. During the period from April to September, ground-level ozone concentrations are also assessed, as their levels often increase to the point of exceeding air quality limits during the warmer months.
If unusually high or above-limit concentrations of sulfur dioxide, nitrogen dioxide, or carbon monoxide occur during the evaluated month, the report also includes an assessment of these pollutants. Evaluations of air pollution by ground-level ozone, often referred to as a "summer" pollutant, are included in reports from April to September. Concentrations of other substances with air quality limits, such as benzo[a]pyrene and heavy metals, cannot be included in the monthly reports due to the time required for sampling and processing.
In accordance with Act 123/1998 Coll. on free access to environmental information, as amended, the CHMI has provided verified primary and aggregated data on outdoor air pollutants. These are the main pollutants with limit values according to current legislation: arsenic (As), benzene, benzo[a]pyrene, cadmium (Cd), carbon monoxide (CO), nickel (Ni), nitrogen dioxide (NO2), nitrogen oxides (NOX), ground-level ozone (O3), lead (Pb), particulate matter (PM10), particulate matter (PM2.5), sulphur dioxide (SO2). The data are based on measurements at stations owned by the CHMI for the period 1969-2022. The primary data are presented in measurement intervals of 30 min, 1 h or 24 h, depending on the type of measurement. Aggregated data are calculated from the above primary data. These data are: daily mean values, monthly mean values, annual mean values and the number of exceedances of the limit values for the protection of human health. Verified data for subsequent calendar years from 2020 will always be available by 1 July of the following year.