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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].

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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.

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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.

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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.

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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.

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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.

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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).

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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.

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