SmogRank / Episodes / Czechia
Czechia, Slovakia and Austria, December 2023
For 2 days, from 13 to 14 December 2023, 16 cities in Czechia, Slovakia and Austria 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 16 in 3 countries
Days 2 13 to 14 December 2023
Worst day 14 December 12 cities counted
Furthest above usual 2.8× Handlová
Day by day
Play 14 December 12 cities at twice their usual or more
Senica Trnava Bratislava Karlova Ves Kroměříž Nitra Zlín Trenčín Győr Židenice Vienna Brno Mödling Olomouc Partizánske Perchtoldsdorf Baden Prievidza Žiar nad Hronom Esztergom Sankt Pölten Zvolen Ružomberok Pardubice Gyál Hradec Králové Dunaújváros Amstetten Pécs České Budějovice Steyr Wolfsberg Linz Ansfelden Poprad Mladá Boleslav Traun Liberec Wels Prague Spišská Nová Ves Kazincbarcika Miskolc Klagenfurt am Wörthersee Beroun 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 Greiz Gera Munich Jena Valašské Meziříčí Frýdek-Místek Havířov Opava Přerov Znojmo Graz Banská Bystrica Martin Klosterneuburg Ostrava Handlová 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 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 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× Bohumín Moravian-Silesian Region, Czechia 2 14 December 14.1 2.6× Ostrava Moravian-Silesian Region, Czechia 1 14 December 14.3 2.5× 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 7 of 13 episodes in Czechia and Slovakia since our records began, by cities reached.
Eastern Europe, December 2023 107 Eastern Europe, March 2023 56 Czechia and Slovakia, November and December 2023 41 Eastern Europe, December 2023 29 Czechia and Austria, October 2023 20 Germany, Slovakia and 2 more countries, June 2023 19 Czechia, Slovakia and Austria, December 2023 16 South-eastern Europe, December 2023 16 Poland and Czechia, April 2023 15 Poland and Czechia, January 2023 15 Czechia and Poland, April 2023 9 Czechia and Slovakia, January 2023 9 Bars: cities reached; colour: the level of the episode's highest daily reading. All 13 .
Use this page SmogRank, Czechia, Slovakia and Austria, December 2023: 16 cities with PM2.5 at twice their usual or more, 13 to 14 December 2023, smogrank.com/episodes/2023-12-czechia-slovakia-and-austria (accessed 2 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.
