SmogRank / Episodes / Czechia

Czechia and Slovakia, January 2023

For 1 day, on 2 January 2023, 9 cities in Czechia, Slovakia and Poland had PM2.5 at least twice their usual for the time of year. The worst reading was Ružomberok, Žilina Region, Slovakia: 54.2 µg/m³ on 2 January, about 2.8× its usual 19.4.

No cause namedWe have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached9in 3 countries
Days12 January 2023
Worst day2 January9 cities counted
Furthest above usual2.8×Ružomberok

Day by day

2 January 9 cities at twice their usual or more
OlomoucZlínValašské MeziříčíOstravaRacibórzBohumínHavířovTrenčínKrapkowiceKędzierzyn-KoźleSenicaŽideniceBrnoJastrzębie ZdrójOpoleČeský TěšínKłodzkoTrnavaŽilinaPartizánskePrievidzaNitraCzechowice-DziedziceMartinBielsko-BialaWrocławBratislavaKatowiceZnojmoŽiar nad HronomHradec KrálovéKlosterneuburgViennaBanská BystricaZvolenGyőrPerchtoldsdorfMödlingBadenJelenia GóraEsztergomSankt PöltenŁaskLiberecMladá BoleslavPopradBogatyniaŁódźZgierzZielona GóraAmstettenŻarySpišská Nová VesČeské BudějovicePragueKazincbarcikaKladnoTarnówDěčínSteyrLinzTraunÚstí nad LabemPrešovŻyrardówStarachowiceWelsJasłoMielecRadomKrosnoKadaňKonstancin-JeziornaHumennéOtwockRzeszówSninaNiskoSokolovJarosławPrzemyślLublinZamośćBerounKošiceFrýdek-MístekLitvínovPilsenVranov nad TopľouKrakówMostRužomberok
30 Dec311 Jan2345
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

RužomberokRužomberok, 30 December: no readingRužomberok, 31 December: no readingRužomberok, 1 January: 74.1 µg/m³, 3.8× usualRužomberok, 2 January: 54.2 µg/m³, 2.8× usualRužomberok, 3 January: no readingRužomberok, 4 January: 20.6 µg/m³, 1.1× usualRužomberok, 5 January: 8.6 µg/m³, 0.4× usualBerounBeroun, 30 December: no readingBeroun, 31 December: no readingBeroun, 1 January: 49.8 µg/m³, 3.0× usualBeroun, 2 January: 35.3 µg/m³, 2.1× usualBeroun, 3 January: 18.3 µg/m³, 1.1× usualBeroun, 4 January: 18.0 µg/m³, 1.1× usualBeroun, 5 January: no readingKrakówKraków, 30 December: no readingKraków, 31 December: no readingKraków, 1 January: 49.3 µg/m³, 2.1× usualKraków, 2 January: 53.9 µg/m³, 2.3× usualKraków, 3 January: no readingKraków, 4 January: 33.7 µg/m³, 1.5× usualKraków, 5 January: 3.2 µg/m³, 0.1× usualFrýdek-MístekFrýdek-Místek, 30 December: no readingFrýdek-Místek, 31 December: no readingFrýdek-Místek, 1 January: 34.0 µg/m³, 2.3× usualFrýdek-Místek, 2 January: 31.5 µg/m³, 2.2× usualFrýdek-Místek, 3 January: 25.0 µg/m³, 1.7× usualFrýdek-Místek, 4 January: 15.6 µg/m³, 1.1× usualFrýdek-Místek, 5 January: no readingVranov nad TopľouVranov nad Topľou, 30 December: no readingVranov nad Topľou, 31 December: no readingVranov nad Topľou, 1 January: 33.4 µg/m³, 2.2× usualVranov nad Topľou, 2 January: 32.9 µg/m³, 2.2× usualVranov nad Topľou, 3 January: no readingVranov nad Topľou, 4 January: 15.3 µg/m³, 1.0× usualVranov nad Topľou, 5 January: 16.5 µg/m³, 1.1× usualLitvínovLitvínov, 30 December: no readingLitvínov, 31 December: no readingLitvínov, 1 January: 30.0 µg/m³, 2.5× usualLitvínov, 2 January: 25.6 µg/m³, 2.2× usualLitvínov, 3 January: 9.0 µg/m³, 0.8× usualLitvínov, 4 January: 8.4 µg/m³, 0.7× usualLitvínov, 5 January: no readingKošiceKošice, 30 December: no readingKošice, 31 December: no readingKošice, 1 January: 29.1 µg/m³, 1.6× usualKošice, 2 January: 38.2 µg/m³, 2.1× usualKošice, 3 January: no readingKošice, 4 January: 18.9 µg/m³, 1.1× usualKošice, 5 January: 16.3 µg/m³, 0.9× usualMostMost, 30 December: no readingMost, 31 December: no readingMost, 1 January: 21.8 µg/m³, 2.0× usualMost, 2 January: 29.6 µg/m³, 2.7× usualMost, 3 January: 8.7 µg/m³, 0.8× usualMost, 4 January: 7.3 µg/m³, 0.7× usualMost, 5 January: no readingPilsenPilsen, 30 December: no readingPilsen, 31 December: no readingPilsen, 1 January: 16.0 µg/m³, 1.4× usualPilsen, 2 January: 25.0 µg/m³, 2.2× usualPilsen, 3 January: 10.6 µg/m³, 0.9× usualPilsen, 4 January: 16.5 µg/m³, 1.4× usualPilsen, 5 January: no reading30 Dec311 Jan2345
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.
Good0–50
Moderate51–100
Sensitive groups101–150
Unhealthy151–200
Very unhealthy201–300
Hazardous301+

Every city it reached

CityDaysHighestUsualAbove usual
RužomberokŽilina Region, Slovakia1 74.11 January19.43.8×
BerounCentral Bohemia, Czechia1 49.81 January16.83.0×
MostÚstí nad Labem Region, Czechia1 29.62 January11.12.7×
LitvínovÚstí nad Labem Region, Czechia1 30.01 January11.82.5×
KrakówLesser Poland, Poland1 53.92 January23.02.3×
Frýdek-MístekMoravian-Silesian Region, Czechia1 34.01 January14.62.3×
Vranov nad TopľouPrešov Region, Slovakia1 33.41 January14.92.2×
PilsenPlzeň Region, Czechia1 25.02 January11.52.2×
KošiceKošice Region, Slovakia1 38.22 January17.92.1×

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 12 of 13 episodes in Czechia and Slovakia since our records began, by cities reached.

Bars: cities reached; colour: the level of the episode's highest daily reading. All 13.

Use this page

SmogRank, Czechia and Slovakia, January 2023: 9 cities with PM2.5 at twice their usual or more, 2 January 2023, smogrank.com/episodes/2023-01-czechia-and-slovakia (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.