SmogRank / Episodes / Czechia

Czechia and Poland, April 2023

For 2 days, from 6 to 7 April 2023, 9 cities in Czechia and Poland had PM2.5 at least twice their usual for the time of year. The worst reading was Bohumín, Moravian-Silesian Region, Czechia: 40.5 µg/m³ on 6 April, about 3.0× its usual 13.7.

No cause namedWe have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached9in 2 countries
Days26 to 7 April 2023
Worst day6 April6 cities counted
Furthest above usual3.3×Frýdek-Místek

Day by day

6 April 6 cities at twice their usual or more
KrapkowiceOpoleRacibórzKędzierzyn-KoźleOlomoucZlínKłodzkoJastrzębie ZdrójWrocławTrenčínŽideniceBrnoKatowiceCzechowice-DziedziceBielsko-BialaŽilinaSenicaMartinPartizánskePrievidzaHradec KrálovéTrnavaNitraŽiar nad HronomRužomberokZnojmoŁaskBratislavaBanská BystricaKościanZvolenKlosterneuburgPoznańViennaKrakówŁódźZgierzPerchtoldsdorfMödlingBadenLiberecEsztergomKutnoMladá BoleslavZielona GóraSankt PöltenŻaryPopradMiędzyrzeczPłockPragueSpišská Nová VesČeské BudějoviceŻyrardówAmstettenKladnoBerounEisenhüttenstadtStarachowiceKazincbarcikaÚstí nad LabemCottbusFrankfurt (Oder)RadomPruszkówMiskolcLinzPrešovMielecSteyrTraunJasłoKošiceWarsawMostKonstancin-JeziornaLitvínovLubnjowWelsWawerOtwockKrosnoPilsenVranov nad TopľouKadaňRzeszówStrausbergPassauHumennéNiskoNeuenhagenNyíregyházaSninaBlankenfelde-MahlowBerlinTeltowKleinmachnowSokolovPotsdamJarosławLublinŁukówSiedlceFalkenseeBurghausenPrzemyślAltenburgWittenbergNauenGreizWeidenTraunreutMarktredwitzBrandenburg an der HavelSchwandorf in BayernZamośćWeißenfelsHalle (Saale)KöthenKelheimJenaBurg bei MagdeburgSaalfeldMagdeburgWeimarMunichStarnbergTarnówDěčínČeský TěšínHavířovJelenia GóraValašské MeziříčíBohumínOstravaFrýdek-Místek
3 Apr45678910
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

BohumínBohumín, 3 April: 5.3 µg/m³, 0.4× usualBohumín, 4 April: 9.4 µg/m³, 0.7× usualBohumín, 5 April: 25.5 µg/m³, 1.9× usualBohumín, 6 April: 40.5 µg/m³, 3.0× usualBohumín, 7 April: 24.1 µg/m³, 1.8× usualBohumín, 8 April: 18.6 µg/m³, 1.4× usualBohumín, 9 April: 34.7 µg/m³, 2.5× usualBohumín, 10 April: 34.8 µg/m³, 2.5× usualFrýdek-MístekFrýdek-Místek, 3 April: 9.5 µg/m³, 0.8× usualFrýdek-Místek, 4 April: 9.1 µg/m³, 0.8× usualFrýdek-Místek, 5 April: 23.8 µg/m³, 2.0× usualFrýdek-Místek, 6 April: 39.9 µg/m³, 3.3× usualFrýdek-Místek, 7 April: 25.8 µg/m³, 2.1× usualFrýdek-Místek, 8 April: 23.4 µg/m³, 1.9× usualFrýdek-Místek, 9 April: 30.8 µg/m³, 2.5× usualFrýdek-Místek, 10 April: 43.0 µg/m³, 3.6× usualHavířovHavířov, 3 April: 9.4 µg/m³, 0.7× usualHavířov, 4 April: 12.2 µg/m³, 0.9× usualHavířov, 5 April: 24.9 µg/m³, 1.8× usualHavířov, 6 April: 36.6 µg/m³, 2.7× usualHavířov, 7 April: 24.8 µg/m³, 1.8× usualHavířov, 8 April: 22.2 µg/m³, 1.6× usualHavířov, 9 April: 33.8 µg/m³, 2.5× usualHavířov, 10 April: 43.5 µg/m³, 3.2× usualOstravaOstrava, 3 April: 7.8 µg/m³, 0.7× usualOstrava, 4 April: 9.3 µg/m³, 0.8× usualOstrava, 5 April: 21.0 µg/m³, 1.8× usualOstrava, 6 April: 35.4 µg/m³, 3.0× usualOstrava, 7 April: 20.2 µg/m³, 1.7× usualOstrava, 8 April: 21.5 µg/m³, 1.8× usualOstrava, 9 April: 30.6 µg/m³, 2.6× usualOstrava, 10 April: 33.4 µg/m³, 2.8× usualValašské MeziříčíValašské Meziříčí, 3 April: 9.5 µg/m³, 0.8× usualValašské Meziříčí, 4 April: 8.3 µg/m³, 0.7× usualValašské Meziříčí, 5 April: 18.5 µg/m³, 1.6× usualValašské Meziříčí, 6 April: 32.9 µg/m³, 2.8× usualValašské Meziříčí, 7 April: 19.2 µg/m³, 1.6× usualValašské Meziříčí, 8 April: 23.9 µg/m³, 2.0× usualValašské Meziříčí, 9 April: 31.4 µg/m³, 2.7× usualValašské Meziříčí, 10 April: 30.9 µg/m³, 2.6× usualČeský TěšínČeský Těšín, 3 April: 12.0 µg/m³, 0.9× usualČeský Těšín, 4 April: 11.0 µg/m³, 0.8× usualČeský Těšín, 5 April: 21.5 µg/m³, 1.6× usualČeský Těšín, 6 April: 32.8 µg/m³, 2.4× usualČeský Těšín, 7 April: 20.6 µg/m³, 1.5× usualČeský Těšín, 8 April: 24.0 µg/m³, 1.7× usualČeský Těšín, 9 April: 34.8 µg/m³, 2.5× usualČeský Těšín, 10 April: 44.0 µg/m³, 3.2× usualJelenia GóraJelenia Góra, 3 April: 5.8 µg/m³, 0.5× usualJelenia Góra, 4 April: 8.0 µg/m³, 0.6× usualJelenia Góra, 5 April: 23.5 µg/m³, 1.9× usualJelenia Góra, 6 April: no readingJelenia Góra, 7 April: 35.2 µg/m³, 2.8× usualJelenia Góra, 8 April: no readingJelenia Góra, 9 April: no readingJelenia Góra, 10 April: 23.0 µg/m³, 1.8× usualDěčínDěčín, 3 April: 8.4 µg/m³, 0.7× usualDěčín, 4 April: 7.7 µg/m³, 0.6× usualDěčín, 5 April: 19.7 µg/m³, 1.6× usualDěčín, 6 April: 24.9 µg/m³, 2.0× usualDěčín, 7 April: 30.7 µg/m³, 2.4× usualDěčín, 8 April: 16.5 µg/m³, 1.3× usualDěčín, 9 April: 29.8 µg/m³, 2.4× usualDěčín, 10 April: 20.7 µg/m³, 1.6× usualTarnówTarnów, 3 April: 8.2 µg/m³, 0.7× usualTarnów, 4 April: 9.5 µg/m³, 0.8× usualTarnów, 5 April: 15.1 µg/m³, 1.2× usualTarnów, 6 April: no readingTarnów, 7 April: 27.5 µg/m³, 2.3× usualTarnów, 8 April: no readingTarnów, 9 April: no readingTarnów, 10 April: 34.9 µg/m³, 2.9× usual3 Apr45678910
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
Frýdek-MístekMoravian-Silesian Region, Czechia2 43.010 April12.13.6×
HavířovMoravian-Silesian Region, Czechia1 43.510 April13.63.2×
Český TěšínMoravian-Silesian Region, Czechia1 44.010 April13.83.2×
OstravaMoravian-Silesian Region, Czechia1 35.46 April11.83.0×
BohumínMoravian-Silesian Region, Czechia1 40.56 April13.73.0×
TarnówLesser Poland, Poland1 34.910 April12.22.9×
Valašské MeziříčíZlín, Czechia1 32.96 April11.72.8×
Jelenia GóraLower Silesia, Poland1 35.27 April12.72.8×
DěčínÚstí nad Labem Region, Czechia1 30.77 April12.62.4×

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 Poland

Number 10 of 13 episodes in Czechia and Poland 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 Poland, April 2023: 9 cities with PM2.5 at twice their usual or more, 6 to 7 April 2023, smogrank.com/episodes/2023-04-czechia-and-poland (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.