SmogRank / Episodes / Czechia
Czechia, Slovakia and 2 more countries, December 2023
For 2 days, from 13 to 14 December 2023, 18 cities in Czechia, Slovakia, Austria and 1 more countries had PM2.5 at least twice their usual for the time of year. The worst reading was Graz, Styria, Austria: 44.5 µg/m³ on 13 December, about 2.1× its usual 21.4.
No cause named We have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached 18 in 4 countries
Days 2 13 to 14 December 2023
Worst day 14 December 14 cities counted
Furthest above usual 2.8× Handlová
Day by day
Play 14 December 14 cities at twice their usual or more
Senica Trnava Bratislava Karlova Ves Kroměříž Zlín Nitra Trenčín Győr Židenice Brno Vienna Olomouc Partizánske Mödling Perchtoldsdorf Baden Prievidza Žiar nad Hronom Esztergom Sankt Pölten Zvolen Ružomberok Pardubice Hradec Králové Gyál Dunaújváros Amstetten České Budějovice Steyr Wolfsberg Linz Ansfelden Mladá Boleslav Poprad Traun Liberec Prague Wels Spišská Nová Ves Kazincbarcika Miskolc Beroun Klagenfurt am Wörthersee Děčín Passau Ústí nad Labem Košice Prešov Teplice Pilsen Most Litvínov Salzburg Vranov nad Topľou Kadaň Nyíregyháza Burghausen Saalfelden am Steinernen Meer Humenné Traunreut Snina Sokolov Schwandorf in Bayern Weiden Marktredwitz Kelheim Altenburg Greiz Gera Munich Jena Valašské Meziříčí Frýdek-Místek Havířov Opava Přerov Znojmo Graz Banská Bystrica Martin Wodzisław Śląski Klosterneuburg Ostrava Handlová Cieszyn Bohumín Český Těšín Třinec Žilina 10 Dec 11 12 13 14 15 16 17 Every measured city in the area, coloured by its PM2.5 that day; a dark ring marks a city at twice its usual or more. Bars: cities counted each day, coloured by their median level. Choose a day or press play; without JavaScript, the days link to that day's world ranking.
How it spread
Bohumín Bohumín, 10 December: 25.4 µg/m³, 1.8× usual Bohumín, 11 December: 8.9 µg/m³, 0.6× usual Bohumín, 12 December: 10.0 µg/m³, 0.7× usual Bohumín, 13 December: 30.8 µg/m³, 2.2× usual Bohumín, 14 December: 36.8 µg/m³, 2.6× usual Bohumín, 15 December: 22.8 µg/m³, 1.6× usual Bohumín, 16 December: 16.3 µg/m³, 1.2× usual Bohumín, 17 December: 8.2 µg/m³, 0.6× usual Wodzisław Śląski Wodzisław Śląski, 10 December: 25.4 µg/m³, 1.6× usual Wodzisław Śląski, 11 December: 8.9 µg/m³, 0.6× usual Wodzisław Śląski, 12 December: 10.0 µg/m³, 0.6× usual Wodzisław Śląski, 13 December: 30.8 µg/m³, 2.0× usual Wodzisław Śląski, 14 December: 36.8 µg/m³, 2.3× usual Wodzisław Śląski, 15 December: 22.8 µg/m³, 1.5× usual Wodzisław Śląski, 16 December: 16.3 µg/m³, 1.0× usual Wodzisław Śląski, 17 December: 8.2 µg/m³, 0.5× usual Graz Graz, 10 December: 38.1 µg/m³, 1.8× usual Graz, 11 December: 42.9 µg/m³, 2.0× usual Graz, 12 December: 45.9 µg/m³, 2.1× usual Graz, 13 December: 44.5 µg/m³, 2.1× usual Graz, 14 December: 31.0 µg/m³, 1.4× usual Graz, 15 December: 20.4 µg/m³, 1.0× usual Graz, 16 December: 24.2 µg/m³, 1.1× usual Graz, 17 December: 31.5 µg/m³, 1.5× usual Banská Bystrica Banská Bystrica, 10 December: 19.7 µg/m³, 1.5× usual Banská Bystrica, 11 December: 24.0 µg/m³, 1.8× usual Banská Bystrica, 12 December: 29.5 µg/m³, 2.3× usual Banská Bystrica, 13 December: 27.0 µg/m³, 2.1× usual Banská Bystrica, 14 December: 28.9 µg/m³, 2.2× usual Banská Bystrica, 15 December: 14.8 µg/m³, 1.1× usual Banská Bystrica, 16 December: 24.2 µg/m³, 1.9× usual Banská Bystrica, 17 December: 36.6 µg/m³, 2.8× usual Handlová Handlová, 10 December: 18.5 µg/m³, 1.5× usual Handlová, 11 December: 15.4 µg/m³, 1.3× usual Handlová, 12 December: 25.4 µg/m³, 2.1× usual Handlová, 13 December: 11.3 µg/m³, 0.9× usual Handlová, 14 December: 29.7 µg/m³, 2.5× usual Handlová, 15 December: 10.9 µg/m³, 0.9× usual Handlová, 16 December: 37.9 µg/m³, 3.2× usual Handlová, 17 December: 24.4 µg/m³, 2.0× usual Žilina Žilina, 10 December: 15.4 µg/m³, 1.0× usual Žilina, 11 December: 22.2 µg/m³, 1.4× usual Žilina, 12 December: 29.3 µg/m³, 1.8× usual Žilina, 13 December: 37.4 µg/m³, 2.3× usual Žilina, 14 December: 44.1 µg/m³, 2.8× usual Žilina, 15 December: 17.9 µg/m³, 1.1× usual Žilina, 16 December: 35.1 µg/m³, 2.2× usual Žilina, 17 December: 30.2 µg/m³, 1.9× usual Martin Martin, 10 December: 15.5 µg/m³, 1.0× usual Martin, 11 December: 17.4 µg/m³, 1.2× usual Martin, 12 December: 24.4 µg/m³, 1.6× usual Martin, 13 December: 32.6 µg/m³, 2.2× usual Martin, 14 December: 24.6 µg/m³, 1.6× usual Martin, 15 December: 13.2 µg/m³, 0.9× usual Martin, 16 December: 30.8 µg/m³, 2.1× usual Martin, 17 December: 28.3 µg/m³, 1.9× usual Znojmo Znojmo, 10 December: 18.4 µg/m³, 1.3× usual Znojmo, 11 December: 11.9 µg/m³, 0.8× usual Znojmo, 12 December: 10.7 µg/m³, 0.7× usual Znojmo, 13 December: 30.9 µg/m³, 2.1× usual Znojmo, 14 December: 23.9 µg/m³, 1.7× usual Znojmo, 15 December: 9.1 µg/m³, 0.6× usual Znojmo, 16 December: 8.6 µg/m³, 0.6× usual Znojmo, 17 December: 11.5 µg/m³, 0.8× usual Klosterneuburg Klosterneuburg, 10 December: 13.4 µg/m³, 1.2× usual Klosterneuburg, 11 December: 22.6 µg/m³, 2.1× usual Klosterneuburg, 12 December: 11.4 µg/m³, 1.0× usual Klosterneuburg, 13 December: 25.3 µg/m³, 2.3× usual Klosterneuburg, 14 December: 11.8 µg/m³, 1.1× usual Klosterneuburg, 15 December: 7.3 µg/m³, 0.7× usual Klosterneuburg, 16 December: 13.0 µg/m³, 1.2× usual Klosterneuburg, 17 December: 9.1 µg/m³, 0.8× usual Ostrava Ostrava, 10 December: 13.8 µg/m³, 1.0× usual Ostrava, 11 December: 8.0 µg/m³, 0.6× usual Ostrava, 12 December: 10.0 µg/m³, 0.7× usual Ostrava, 13 December: 24.8 µg/m³, 1.7× usual Ostrava, 14 December: 35.9 µg/m³, 2.5× usual Ostrava, 15 December: 22.4 µg/m³, 1.6× usual Ostrava, 16 December: 16.9 µg/m³, 1.2× usual Ostrava, 17 December: 11.9 µg/m³, 0.8× usual Třinec Třinec, 10 December: 12.1 µg/m³, 1.0× usual Třinec, 11 December: 8.0 µg/m³, 0.6× usual Třinec, 12 December: 8.0 µg/m³, 0.6× usual Třinec, 13 December: 10.0 µg/m³, 0.8× usual Třinec, 14 December: 35.4 µg/m³, 2.8× usual Třinec, 15 December: 22.4 µg/m³, 1.8× usual Třinec, 16 December: 21.7 µg/m³, 1.7× usual Třinec, 17 December: 11.8 µg/m³, 0.9× usual Havířov Havířov, 10 December: 17.3 µg/m³, 1.0× usual Havířov, 11 December: 4.6 µg/m³, 0.3× usual Havířov, 12 December: 9.6 µg/m³, 0.6× usual Havířov, 13 December: 22.6 µg/m³, 1.3× usual Havířov, 14 December: 35.2 µg/m³, 2.1× usual Havířov, 15 December: 27.9 µg/m³, 1.6× usual Havířov, 16 December: 18.6 µg/m³, 1.1× usual Havířov, 17 December: 8.9 µg/m³, 0.5× usual Český Těšín Český Těšín, 10 December: 14.2 µg/m³, 1.3× usual Český Těšín, 11 December: no reading Český Těšín, 12 December: 8.4 µg/m³, 0.8× usual Český Těšín, 13 December: 12.2 µg/m³, 1.1× usual Český Těšín, 14 December: 30.5 µg/m³, 2.8× usual Český Těšín, 15 December: 21.1 µg/m³, 1.9× usual Český Těšín, 16 December: 22.7 µg/m³, 2.1× usual Český Těšín, 17 December: 12.0 µg/m³, 1.1× usual Cieszyn Cieszyn, 10 December: 14.2 µg/m³, 1.2× usual Cieszyn, 11 December: no reading Cieszyn, 12 December: 8.4 µg/m³, 0.7× usual Cieszyn, 13 December: 12.2 µg/m³, 1.1× usual Cieszyn, 14 December: 30.5 µg/m³, 2.6× usual Cieszyn, 15 December: 21.1 µg/m³, 1.8× usual Cieszyn, 16 December: 22.7 µg/m³, 2.0× usual Cieszyn, 17 December: 12.0 µg/m³, 1.0× usual Frýdek-Místek Frýdek-Místek, 10 December: 9.3 µg/m³, 0.7× usual Frýdek-Místek, 11 December: no reading Frýdek-Místek, 12 December: 10.1 µg/m³, 0.7× usual Frýdek-Místek, 13 December: 23.0 µg/m³, 1.6× usual Frýdek-Místek, 14 December: 30.2 µg/m³, 2.1× usual Frýdek-Místek, 15 December: 24.0 µg/m³, 1.7× usual Frýdek-Místek, 16 December: 13.4 µg/m³, 0.9× usual Frýdek-Místek, 17 December: 8.6 µg/m³, 0.6× usual Přerov Přerov, 10 December: 15.9 µg/m³, 1.1× usual Přerov, 11 December: 12.2 µg/m³, 0.9× usual Přerov, 12 December: 10.6 µg/m³, 0.8× usual Přerov, 13 December: 18.7 µg/m³, 1.3× usual Přerov, 14 December: 30.1 µg/m³, 2.1× usual Přerov, 15 December: 16.0 µg/m³, 1.1× usual Přerov, 16 December: 23.1 µg/m³, 1.6× usual Přerov, 17 December: 16.0 µg/m³, 1.1× usual Opava Opava, 10 December: 10.3 µg/m³, 0.7× usual Opava, 11 December: 7.1 µg/m³, 0.5× usual Opava, 12 December: 6.9 µg/m³, 0.5× usual Opava, 13 December: 14.6 µg/m³, 1.0× usual Opava, 14 December: 29.5 µg/m³, 2.1× usual Opava, 15 December: 19.5 µg/m³, 1.4× usual Opava, 16 December: 11.3 µg/m³, 0.8× usual Opava, 17 December: 8.6 µg/m³, 0.6× usual Valašské Meziříčí Valašské Meziříčí, 10 December: 12.6 µg/m³, 0.9× usual Valašské Meziříčí, 11 December: 7.4 µg/m³, 0.5× usual Valašské Meziříčí, 12 December: 13.0 µg/m³, 0.9× usual Valašské Meziříčí, 13 December: 15.7 µg/m³, 1.1× usual Valašské Meziříčí, 14 December: 29.0 µg/m³, 2.0× usual Valašské Meziříčí, 15 December: 24.3 µg/m³, 1.7× usual Valašské Meziříčí, 16 December: 30.6 µg/m³, 2.2× usual Valašské Meziříčí, 17 December: 17.1 µg/m³, 1.2× usual 10 Dec 11 12 13 14 15 16 17 Every counted city, in the order the episode reached them, 3 days before to 3 after. Each square is a day, coloured by that day's PM2.5; outlined: at twice the city's usual or more. Good 0–50
Moderate 51–100
Sensitive groups 101–150
Unhealthy 151–200
Very unhealthy 201–300
Hazardous 301+
Every city it reached
City Days Highest Usual Above usual
Handlová Trenčín Region, Slovakia 1 16 December 12.0 3.2× Banská Bystrica Banská Bystrica Region, Slovakia 2 17 December 13.0 2.8× Třinec Moravian-Silesian Region, Czechia 1 14 December 12.7 2.8× Český Těšín Moravian-Silesian Region, Czechia 1 14 December 11.0 2.8× Žilina Žilina Region, Slovakia 2 14 December 16.0 2.8× Cieszyn Silesia, Poland 1 14 December 11.6 2.6× Bohumín Moravian-Silesian Region, Czechia 2 14 December 14.1 2.6× Ostrava Moravian-Silesian Region, Czechia 1 14 December 14.3 2.5× Wodzisław Śląski Silesia, Poland 1 14 December 15.7 2.3× Klosterneuburg Lower Austria, Austria 1 13 December 11.0 2.3× Martin Žilina Region, Slovakia 1 13 December 15.0 2.2× Valašské Meziříčí Zlín, Czechia 1 16 December 14.2 2.2× Znojmo South Moravian, Czechia 1 13 December 14.4 2.1× Graz Styria, Austria 1 12 December 21.4 2.1× Přerov Olomouc Region, Czechia 1 14 December 14.1 2.1× Frýdek-Místek Moravian-Silesian Region, Czechia 1 14 December 14.3 2.1× Opava Moravian-Silesian Region, Czechia 1 14 December 14.1 2.1× Havířov Moravian-Silesian Region, Czechia 1 14 December 17.1 2.1×
Daily means in µg/m³. Usual: the city's median for this time of year (its days within 21 days of the date, every year, leaving out the week around it). Above usual: its highest day against that.
Against other episodes in Czechia and Slovakia
Number 10 of 21 episodes in Czechia and Slovakia since our records began, by cities reached.
Eastern Europe, December 2023 110 Eastern Europe, March 2023 56 Eastern Europe, November and December 2023 43 South-eastern Europe, December 2023 to January 2024 34 Eastern Europe, January 2025 26 Eastern Europe, January 2024 26 Eastern Europe, April 2026 24 Czechia and Austria, October 2023 21 Germany, Slovakia and 2 more countries, June 2023 19 Czechia, Slovakia and 2 more countries, December 2023 18 Czechia and Poland, November 2025 17 Eastern Europe, July 2024 17 Bars: cities reached; colour: the level of the episode's highest daily reading. All 21 .
Use this page SmogRank, Czechia, Slovakia and 2 more countries, December 2023: 18 cities with PM2.5 at twice their usual or more, 13 to 14 December 2023, smogrank.com/episodes/2023-12-czechia-slovakia-and-2-more-countries (accessed 3 October 2026).
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You're welcome to reuse a single chart, image or figure with this citation and a link. Terms .
An episode is a run of days when many cities close to each other (four or more within 350 km on a day, 8 or more in all) each had a daily PM2.5 mean of at least 25 µg/m³ and at least 2 times their usual for that time of year. Found in our own measurements, not picked by hand. How we find episodes . Values are each city's daily mean of its own monitors; causes are the usual kinds for a pattern like this, not a confirmed source.
