SmogRank / Episodes / Czechia

Czechia, Slovakia and Poland, 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-KoźleSenicaŽideniceWodzisław ŚląskiBrnoJastrzębie ZdrójOpoleČeský TěšínCieszynKłodzkoTrnavaŽilinaPartizánskePrievidzaNitraCzechowice-DziedziceMartinBielsko-BialaWrocławBratislavaKatowiceZnojmoŽiar nad HronomHradec KrálovéKlosterneuburgViennaBanská BystricaZvolenGyőrPerchtoldsdorfMödlingBadenJelenia GóraEsztergomSankt PöltenŁaskLiberecMladá BoleslavPopradBogatyniaŁódźZgierzZielona GóraAmstettenŻarySpišská Nová VesČeské BudějovicePragueKazincbarcikaKladnoTarnówDěčínSteyrLinzTraunÚstí nad LabemPrešovŻyrardówStarachowiceWelsJasłoMielecRadomKrosnoKadaňKonstancin-JeziornaHumennéOtwockRzeszówSninaNiskoSokolovJarosławPrzemyślLublinZamośćBerounKošicePilsenLitvínovFrýdek-MístekVranov 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/m³Ružomberok, 2 January: 54.2 µg/m³, 2.8× its usual 19.4Ružomberok, 3 January: no readingRužomberok, 4 January: 20.6 µg/m³Ružomberok, 5 January: 8.6 µg/m³KrakówKraków, 30 December: no readingKraków, 31 December: no readingKraków, 1 January: 49.3 µg/m³Kraków, 2 January: 53.9 µg/m³, 2.3× its usual 23.0Kraków, 3 January: no readingKraków, 4 January: 33.7 µg/m³Kraków, 5 January: 3.2 µg/m³KošiceKošice, 30 December: no readingKošice, 31 December: no readingKošice, 1 January: 29.1 µg/m³Košice, 2 January: 38.2 µg/m³, 2.1× its usual 17.9Košice, 3 January: no readingKošice, 4 January: 18.9 µg/m³Košice, 5 January: 16.3 µg/m³BerounBeroun, 30 December: no readingBeroun, 31 December: no readingBeroun, 1 January: 49.8 µg/m³Beroun, 2 January: 35.3 µg/m³, 2.1× its usual 16.8Beroun, 3 January: 18.3 µg/m³Beroun, 4 January: 18.0 µg/m³Beroun, 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/m³Vranov nad Topľou, 2 January: 32.9 µg/m³, 2.2× its usual 14.9Vranov nad Topľou, 3 January: no readingVranov nad Topľou, 4 January: 15.3 µg/m³Vranov nad Topľou, 5 January: 16.5 µg/m³Frýdek-MístekFrýdek-Místek, 30 December: no readingFrýdek-Místek, 31 December: no readingFrýdek-Místek, 1 January: 34.0 µg/m³Frýdek-Místek, 2 January: 31.5 µg/m³, 2.2× its usual 14.6Frýdek-Místek, 3 January: 25.0 µg/m³Frýdek-Místek, 4 January: 15.6 µg/m³Frýdek-Místek, 5 January: no readingMostMost, 30 December: no readingMost, 31 December: no readingMost, 1 January: 21.8 µg/m³Most, 2 January: 29.6 µg/m³, 2.7× its usual 11.1Most, 3 January: 8.7 µg/m³Most, 4 January: 7.3 µg/m³Most, 5 January: no readingLitvínovLitvínov, 30 December: no readingLitvínov, 31 December: no readingLitvínov, 1 January: 30.0 µg/m³Litvínov, 2 January: 25.6 µg/m³, 2.2× its usual 11.8Litvínov, 3 January: 9.0 µg/m³Litvínov, 4 January: 8.4 µg/m³Litvínov, 5 January: no readingPilsenPilsen, 30 December: no readingPilsen, 31 December: no readingPilsen, 1 January: 16.0 µg/m³Pilsen, 2 January: 25.0 µg/m³, 2.2× its usual 11.5Pilsen, 3 January: 10.6 µg/m³Pilsen, 4 January: 16.5 µg/m³Pilsen, 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 54.22 January19.42.8×
MostÚstí nad Labem Region, Czechia1 29.62 January11.12.7×
KrakówLesser Poland, Poland1 53.92 January23.02.3×
Vranov nad TopľouPrešov Region, Slovakia1 32.92 January14.92.2×
Frýdek-MístekMoravian-Silesian Region, Czechia1 31.52 January14.62.2×
LitvínovÚstí nad Labem Region, Czechia1 25.62 January11.82.2×
PilsenPlzeň Region, Czechia1 25.02 January11.52.2×
KošiceKošice Region, Slovakia1 38.22 January17.92.1×
BerounCentral Bohemia, Czechia1 35.32 January16.82.1×

Daily means in µg/m³, over the days each city counted in this episode. Highest: its highest of those days. Usual: the city's median for the time of year of that day (its days within 21 days of the date, every year, leaving out the week around it). Above usual: its highest day against that, with a usual under 5 µg/m³ taken as 5.

Against other episodes in Czechia and Slovakia

Number 20 of 22 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 22.

Use this page

SmogRank, Czechia, Slovakia and Poland, January 2023: 9 cities with PM2.5 at twice their usual or more, 2 January 2023, smogrank.com/episodes/2023-01-czechia-slovakia-and-poland (accessed 4 October 2026).

Download top 10 (PNG)

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.