Eastern Europe, November 2024
For 11 days, from 3 to 13 November 2024, 260 cities in Germany, Poland, Czechia and 13 more countries had PM2.5 at least twice their usual for the time of year. The worst reading was Negotin, Central Serbia, Serbia: 180.0 µg/m³ on 8 November, about 2.5× its usual 72.4.
Day by day
How it spread
Every city it reached
| City | Days | Highest | Above usual |
|---|---|---|---|
| PécsBaranya, Hungary | 7 | 110.42 November | 10× |
| KöthenSaxony-Anhalt, Germany | 2 | 52.19 November | 10× |
| HalberstadtSaxony-Anhalt, Germany | 1 | 44.79 November | 8.9× |
| LiberpolisCounty of Osijek-Baranja, Croatia | 4 | 47.28 November | 8.7× |
| WolfsburgLower Saxony, Germany | 2 | 45.09 November | 8.2× |
| DelmenhorstLower Saxony, Germany | 3 | 48.111 November | 8.0× |
| Burg bei MagdeburgSaxony-Anhalt, Germany | 1 | 42.39 November | 8.0× |
| MagdeburgSaxony-Anhalt, Germany | 2 | 51.49 November | 7.8× |
| SalzgitterLower Saxony, Germany | 1 | 38.29 November | 7.6× |
| Hansestadt SalzwedelSaxony-Anhalt, Germany | 2 | 38.39 November | 7.5× |
| BraunschweigLower Saxony, Germany | 1 | 37.49 November | 7.3× |
| BernburgSaxony-Anhalt, Germany | 4 | 61.79 November | 7.2× |
| Ústí nad LabemÚstí nad Labem Region, Czechia | 6 | 68.910 November | 7.0× |
| GeraThuringia, Germany | 3 | 36.29 November | 6.7× |
| HildesheimLower Saxony, Germany | 1 | 34.59 November | 6.6× |
| BremerhavenBremen, Germany | 2 | 41.69 November | 6.6× |
| BihaćFederation of B&H, Bosnia and Herzegovina | 7 | 56.011 November | 6.6× |
| AltenburgThuringia, Germany | 2 | 37.49 November | 6.6× |
| Bitterfeld-WolfenSaxony-Anhalt, Germany | 2 | 49.89 November | 6.6× |
| LübeckSchleswig-Holstein, Germany | 2 | 32.59 November | 6.5× |
| WittenbergSaxony-Anhalt, Germany | 4 | 50.09 November | 6.4× |
| WismarMecklenburg-Vorpommern, Germany | 2 | 40.29 November | 6.4× |
| KelheimBavaria, Germany | 2 | 40.19 November | 6.4× |
| SchwerinMecklenburg-Vorpommern, Germany | 2 | 44.09 November | 6.3× |
| HamburgHamburg, Germany | 2 | 39.99 November | 6.2× |
| HalstenbekSchleswig-Holstein, Germany | 2 | 39.99 November | 6.2× |
| WilhelmshavenLower Saxony, Germany | 1 | 32.99 November | 6.1× |
| JenaThuringia, Germany | 2 | 32.79 November | 6.1× |
| WeißenfelsSaxony-Anhalt, Germany | 2 | 31.49 November | 6.0× |
| TepliceÚstí nad Labem Region, Czechia | 5 | 53.610 November | 6.0× |
| KadaňÚstí nad Labem Region, Czechia | 4 | 46.39 November | 6.0× |
| WittenbergeBrandenburg, Germany | 2 | 33.69 November | 6.0× |
| OytenLower Saxony, Germany | 2 | 36.09 November | 6.0× |
| WernigerodeSaxony-Anhalt, Germany | 1 | 36.59 November | 6.0× |
| DessauSaxony-Anhalt, Germany | 3 | 53.29 November | 6.0× |
| GreizThuringia, Germany | 3 | 40.89 November | 5.9× |
| SokolovCarlsbad Region, Czechia | 3 | 41.79 November | 5.9× |
| Novi SadVojvodina, Serbia | 10 | 82.88 November | 5.9× |
| JarosławSubcarpathia, Poland | 3 | 95.47 November | 5.9× |
| StralsundMecklenburg-Vorpommern, Germany | 2 | 32.79 November | 5.8× |
| ItzehoeSchleswig-Holstein, Germany | 1 | 28.69 November | 5.7× |
| KrosnoSubcarpathia, Poland | 6 | 48.47 November | 5.7× |
| Halle (Saale)Saxony-Anhalt, Germany | 1 | 39.09 November | 5.7× |
| MarktredwitzBavaria, Germany | 2 | 38.39 November | 5.6× |
| GoslarLower Saxony, Germany | 1 | 27.59 November | 5.5× |
| Frýdek-MístekMoravian-Silesian Region, Czechia | 7 | 53.88 November | 5.5× |
| KroměřížZlín, Czechia | 2 | 42.88 November | 5.5× |
| RostockMecklenburg-Vorpommern, Germany | 2 | 34.59 November | 5.5× |
| KielSchleswig-Holstein, Germany | 2 | 27.39 November | 5.5× |
| TřinecMoravian-Silesian Region, Czechia | 6 | 49.18 November | 5.5× |
| Brandenburg an der HavelBrandenburg, Germany | 2 | 36.49 November | 5.4× |
| MostÚstí nad Labem Region, Czechia | 4 | 44.810 November | 5.4× |
| ŽideniceSouth Moravian, Czechia | 3 | 54.58 November | 5.3× |
| HannoverLower Saxony, Germany | 1 | 29.79 November | 5.3× |
| SaalfeldThuringia, Germany | 2 | 27.59 November | 5.3× |
| NeuruppinBrandenburg, Germany | 2 | 32.09 November | 5.2× |
| České BudějoviceSouth Bohemian Region, Czechia | 2 | 45.88 November | 5.2× |
| Novo MestoUrban Municipality of Novo Mesto, Slovenia | 8 | 66.89 November | 5.2× |
| MolFlanders, Belgium | 1 | 32.911 November | 5.1× |
| CieszynSilesia, Poland | 7 | 49.18 November | 5.1× |
| SuhlThuringia, Germany | 2 | 29.19 November | 5.1× |
| FalkenseeBrandenburg, Germany | 2 | 30.19 November | 5.1× |
| PotsdamBrandenburg, Germany | 2 | 33.19 November | 5.1× |
| DębicaSubcarpathia, Poland | 4 | 74.66 November | 5.1× |
| DěčínÚstí nad Labem Region, Czechia | 5 | 72.010 November | 5.1× |
| PilsenPlzeň Region, Czechia | 5 | 45.39 November | 5.0× |
| KladnoCentral Bohemia, Czechia | 3 | 49.79 November | 5.0× |
| FlensburgSchleswig-Holstein, Germany | 1 | 25.610 November | 5.0× |
| BremenBremen, Germany | 2 | 33.110 November | 5.0× |
| ErfurtThuringia, Germany | 1 | 25.98 November | 5.0× |
| MielecSubcarpathia, Poland | 4 | 81.56 November | 5.0× |
| Valašské MeziříčíZlín, Czechia | 7 | 51.78 November | 4.9× |
| WeimarThuringia, Germany | 2 | 27.48 November | 4.9× |
| PraguePrague, Czechia | 5 | 45.79 November | 4.9× |
| Český TěšínMoravian-Silesian Region, Czechia | 7 | 49.18 November | 4.9× |
| BohumínMoravian-Silesian Region, Czechia | 7 | 55.47 November | 4.9× |
| LitvínovÚstí nad Labem Region, Czechia | 5 | 47.29 November | 4.8× |
| GyőrGyőr-Moson-Sopron, Hungary | 5 | 55.39 November | 4.8× |
| TrbovljeMunicipality of Trbovlje, Slovenia | 7 | 46.99 November | 4.8× |
| PardubicePardubice Region, Czechia | 6 | 48.610 November | 4.8× |
| LubnjowBrandenburg, Germany | 2 | 29.49 November | 4.7× |
| Wodzisław ŚląskiSilesia, Poland | 7 | 55.47 November | 4.7× |
| LyonAuvergne-Rhône-Alpes, France | 1 | 28.29 November | 4.7× |
| CottbusBrandenburg, Germany | 3 | 34.39 November | 4.7× |
| WürzburgBavaria, Germany | 2 | 31.910 November | 4.7× |
| GüstrowMecklenburg-Vorpommern, Germany | 1 | 29.59 November | 4.7× |
| MariborUrban Municipality of Maribor, Slovenia | 6 | 40.69 November | 4.7× |
| IaşiIași County, Romania | 3 | 67.68 November | 4.7× |
| PtujUrban Municipality of Ptuj, Slovenia | 7 | 50.39 November | 4.7× |
| AnnemasseAuvergne-Rhône-Alpes, France | 1 | 25.99 November | 4.6× |
| KielceŚwiętokrzyskie, Poland | 2 | 88.56 November | 4.6× |
| ValenceAuvergne-Rhône-Alpes, France | 2 | 28.18 November | 4.6× |
| EisenhüttenstadtBrandenburg, Germany | 3 | 32.19 November | 4.6× |
| OldenburgLower Saxony, Germany | 2 | 33.89 November | 4.6× |
| KoperUrban Municipality of Koper, Slovenia | 1 | 27.48 November | 4.6× |
| WeidenBavaria, Germany | 3 | 39.79 November | 4.6× |
| OstravaMoravian-Silesian Region, Czechia | 7 | 48.67 November | 4.5× |
| CoburgBavaria, Germany | 1 | 25.79 November | 4.5× |
| PopradPrešov Region, Slovakia | 1 | 28.413 November | 4.5× |
| Schwandorf in BayernBavaria, Germany | 3 | 32.99 November | 4.5× |
| ŽilinaŽilina Region, Slovakia | 7 | 55.29 November | 4.5× |
| ZlínZlín, Czechia | 4 | 41.78 November | 4.5× |
| BelgradeCentral Serbia, Serbia | 7 | 80.08 November | 4.4× |
| PřerovOlomouc Region, Czechia | 6 | 52.28 November | 4.4× |
| NurembergBavaria, Germany | 2 | 30.09 November | 4.4× |
| SninaPrešov Region, Slovakia | 1 | 34.012 November | 4.4× |
| Banja LukaSrpska, Bosnia and Herzegovina | 1 | 159.07 November | 4.4× |
| Hradec KrálovéHradec Králové Region, Czechia | 7 | 49.88 November | 4.3× |
| Schwedt (Oder)Brandenburg, Germany | 1 | 29.89 November | 4.3× |
| Kędzierzyn-KoźleOpole Voivodeship, Poland | 8 | 55.77 November | 4.3× |
| Mladá BoleslavCentral Bohemia, Czechia | 6 | 43.610 November | 4.3× |
| BambergBavaria, Germany | 1 | 26.29 November | 4.3× |
| DziałdowoWarmia-Masuria, Poland | 2 | 84.35 November | 4.3× |
| ZamośćLublin, Poland | 3 | 76.66 November | 4.3× |
| MunichBavaria, Germany | 1 | 25.112 November | 4.3× |
| HavířovMoravian-Silesian Region, Czechia | 7 | 51.58 November | 4.2× |
| NordhausenThuringia, Germany | 1 | 27.79 November | 4.2× |
| SremčicaCentral Serbia, Serbia | 5 | 93.98 November | 4.2× |
| LjubljanaLjubljana, Slovenia | 7 | 45.29 November | 4.2× |
| Romans-sur-IsèreAuvergne-Rhône-Alpes, France | 2 | 30.88 November | 4.2× |
| LuckenwaldeBrandenburg, Germany | 1 | 31.49 November | 4.1× |
| OpoleOpole Voivodeship, Poland | 8 | 58.811 November | 4.1× |
| Königs WusterhausenBrandenburg, Germany | 2 | 32.09 November | 4.1× |
| ŁukówLublin, Poland | 2 | 82.06 November | 4.1× |
| LiberecLiberec Region, Czechia | 5 | 37.111 November | 4.1× |
| CeljeUrban Municipality of Celje, Slovenia | 8 | 50.89 November | 4.1× |
| NyíregyházaSzabolcs-Szatmár-Bereg, Hungary | 5 | 59.77 November | 4.1× |
| FriesoytheLower Saxony, Germany | 1 | 25.99 November | 4.0× |
| BrnoSouth Moravian, Czechia | 5 | 45.68 November | 4.0× |
| RacibórzSilesia, Poland | 8 | 64.17 November | 4.0× |
| IngolstadtBavaria, Germany | 3 | 46.99 November | 4.0× |
| MartinŽilina Region, Slovakia | 6 | 48.511 November | 4.0× |
| HandlováTrenčín Region, Slovakia | 7 | 38.411 November | 4.0× |
| AugsburgBavaria, Germany | 1 | 25.511 November | 4.0× |
| ZnojmoSouth Moravian, Czechia | 6 | 48.88 November | 4.0× |
| Czechowice-DziedziceSilesia, Poland | 6 | 69.47 November | 4.0× |
| Blankenfelde-MahlowBrandenburg, Germany | 1 | 27.99 November | 3.9× |
| LublinLublin, Poland | 3 | 75.76 November | 3.9× |
| VeszprémVeszprém, Hungary | 4 | 38.38 November | 3.9× |
| PrizrenPrizren, Kosovo | 2 | 34.09 November | 3.9× |
| KošiceKošice Region, Slovakia | 5 | 53.511 November | 3.8× |
| KatowiceSilesia, Poland | 4 | 61.67 November | 3.8× |
| NitraNitra Region, Slovakia | 6 | 39.710 November | 3.8× |
| StrausbergBrandenburg, Germany | 1 | 25.39 November | 3.8× |
| Frankfurt (Oder)Brandenburg, Germany | 3 | 30.29 November | 3.8× |
| Jelenia GóraLower Silesia, Poland | 8 | 51.511 November | 3.8× |
| DunaújvárosFejér, Hungary | 7 | 40.28 November | 3.8× |
| KłodzkoLower Silesia, Poland | 7 | 59.37 November | 3.6× |
| Banská BystricaBanská Bystrica Region, Slovakia | 2 | 31.812 November | 3.6× |
| SzegedCsongrád, Hungary | 6 | 44.412 November | 3.6× |
| PrešovPrešov Region, Slovakia | 5 | 53.611 November | 3.6× |
| GyöngyösHeves County, Hungary | 1 | 28.611 November | 3.6× |
| OlomoucOlomouc Region, Czechia | 4 | 48.47 November | 3.5× |
| SereďTrnava Region, Slovakia | 5 | 44.810 November | 3.5× |
| NeubrandenburgMecklenburg-Vorpommern, Germany | 1 | 33.89 November | 3.5× |
| PassauBavaria, Germany | 4 | 35.18 November | 3.5× |
| KościerzynaPomerania, Poland | 2 | 42.04 November | 3.5× |
| SarajevoFederation of B&H, Bosnia and Herzegovina | 5 | 105.08 November | 3.5× |
| EsztergomKomárom-Esztergom, Hungary | 6 | 43.211 November | 3.4× |
| BogatyniaLower Silesia, Poland | 5 | 34.311 November | 3.4× |
| ZemunCentral Serbia, Serbia | 4 | 103.08 November | 3.4× |
| SenicaTrnava Region, Slovakia | 5 | 31.510 November | 3.4× |
| PułtuskMazovia, Poland | 2 | 52.26 November | 3.3× |
| Zielona GóraLubusz, Poland | 6 | 40.710 November | 3.3× |
| GoriziaFriuli Venezia Giulia, Italy | 2 | 34.98 November | 3.3× |
| RzeszówSubcarpathia, Poland | 4 | 46.37 November | 3.3× |
| BratislavaBratislava Region, Slovakia | 5 | 32.710 November | 3.3× |
| MühlhausenThuringia, Germany | 1 | 27.19 November | 3.3× |
| TrenčínTrenčín Region, Slovakia | 7 | 39.510 November | 3.3× |
| Bielsko-BialaSilesia, Poland | 6 | 62.28 November | 3.3× |
| Vranov nad TopľouPrešov Region, Slovakia | 5 | 40.511 November | 3.2× |
| BucharestBucharest, Romania | 3 | 45.88 November | 3.2× |
| OtwockMazovia, Poland | 3 | 71.36 November | 3.2× |
| Cluj-NapocaCluj County, Romania | 6 | 50.69 November | 3.2× |
| TrnavaTrnava Region, Slovakia | 4 | 33.98 November | 3.2× |
| ObrenovacCentral Serbia, Serbia | 6 | 98.38 November | 3.2× |
| RadomskoŁódź Voivodeship, Poland | 3 | 60.76 November | 3.1× |
| BerounCentral Bohemia, Czechia | 4 | 41.28 November | 3.1× |
| KranjUrban Municipality of Kranj, Slovenia | 7 | 35.59 November | 3.1× |
| Bernau bei BerlinBrandenburg, Germany | 1 | 27.09 November | 3.1× |
| ZvolenBanská Bystrica Region, Slovakia | 4 | 38.611 November | 3.1× |
| KazincbarcikaBorsod-Abaúj-Zemplén, Hungary | 6 | 60.88 November | 3.1× |
| PezinokBratislava Region, Slovakia | 4 | 44.512 November | 3.1× |
| ČadcaŽilina Region, Slovakia | 5 | 49.510 November | 3.1× |
| ŚwiecieKujawsko-Pomorskie, Poland | 3 | 47.05 November | 3.1× |
| Strzelce OpolskieOpole Voivodeship, Poland | 5 | 42.47 November | 3.0× |
| GrajewoPodlasie, Poland | 1 | 49.36 November | 3.0× |
| WarsawMazovia, Poland | 1 | 49.86 November | 3.0× |
| Žiar nad HronomBanská Bystrica Region, Slovakia | 1 | 26.611 November | 3.0× |
| KomárnoNitra Region, Slovakia | 7 | 42.710 November | 3.0× |
| DejCluj County, Romania | 6 | 80.49 November | 3.0× |
| SmederevoCentral Serbia, Serbia | 4 | 111.39 November | 3.0× |
| PrievidzaTrenčín Region, Slovakia | 3 | 32.111 November | 2.9× |
| NiskoSubcarpathia, Poland | 2 | 63.07 November | 2.9× |
| RužomberokŽilina Region, Slovakia | 6 | 42.09 November | 2.9× |
| CodleaBrașov County, Romania | 3 | 71.48 November | 2.9× |
| ŻywiecSilesia, Poland | 2 | 76.78 November | 2.9× |
| PančevoVojvodina, Serbia | 4 | 77.79 November | 2.9× |
| HumennéPrešov Region, Slovakia | 6 | 37.210 November | 2.9× |
| JasłoSubcarpathia, Poland | 3 | 40.77 November | 2.9× |
| FutogVojvodina, Serbia | 5 | 71.98 November | 2.9× |
| BotevgradSofia, Bulgaria | 4 | 35.19 November | 2.9× |
| SallanchesAuvergne-Rhône-Alpes, France | 1 | 27.116 November | 2.9× |
| TravnikFederation of B&H, Bosnia and Herzegovina | 3 | 101.07 November | 2.8× |
| KrakówLesser Poland, Poland | 2 | 53.97 November | 2.8× |
| PrzemyślSubcarpathia, Poland | 3 | 51.37 November | 2.8× |
| DebrecenHajdú-Bihar, Hungary | 5 | 84.57 November | 2.8× |
| NáchodHradec Králové Region, Czechia | 4 | 53.97 November | 2.7× |
| RadomMazovia, Poland | 2 | 50.67 November | 2.7× |
| ZgierzŁódź Voivodeship, Poland | 2 | 70.96 November | 2.7× |
| ŁódźŁódź Voivodeship, Poland | 1 | 49.56 November | 2.7× |
| AugustówPodlasie, Poland | 2 | 60.86 November | 2.7× |
| BardejovPrešov Region, Slovakia | 3 | 37.011 November | 2.7× |
| Konstancin-JeziornaMazovia, Poland | 1 | 46.76 November | 2.7× |
| OlsztynWarmia-Masuria, Poland | 1 | 35.96 November | 2.7× |
| ŻaryLubusz, Poland | 4 | 31.212 November | 2.6× |
| KragujevacCentral Serbia, Serbia | 1 | 97.29 November | 2.6× |
| ŻyrardówMazovia, Poland | 2 | 44.95 November | 2.6× |
| CraiovaDolj, Romania | 3 | 31.98 November | 2.6× |
| WrocławLower Silesia, Poland | 4 | 43.410 November | 2.6× |
| SzczecinWest Pomerania, Poland | 3 | 32.19 November | 2.6× |
| KaliszGreater Poland, Poland | 2 | 51.36 November | 2.6× |
| NišCentral Serbia, Serbia | 4 | 73.18 November | 2.6× |
| BorCentral Serbia, Serbia | 1 | 45.79 November | 2.6× |
| PúchovTrenčín Region, Slovakia | 7 | 46.510 November | 2.6× |
| Jastrzębie ZdrójSilesia, Poland | 2 | 53.27 November | 2.5× |
| NegotinCentral Serbia, Serbia | 3 | 180.08 November | 2.5× |
| Liptovský Mikulᚎilina Region, Slovakia | 2 | 35.812 November | 2.5× |
| TeltowBrandenburg, Germany | 1 | 26.311 November | 2.5× |
| WinterthurZurich, Switzerland | 3 | 29.516 November | 2.5× |
| KraljevoCentral Serbia, Serbia | 2 | 117.09 November | 2.5× |
| LegionowoMazovia, Poland | 2 | 48.06 November | 2.5× |
| TarnówLesser Poland, Poland | 3 | 34.311 November | 2.5× |
| LučenecBanská Bystrica Region, Slovakia | 4 | 46.516 November | 2.5× |
| WawerMazovia, Poland | 1 | 45.86 November | 2.4× |
| MiskolcBorsod-Abaúj-Zemplén, Hungary | 3 | 50.311 November | 2.4× |
| ŁaskŁódź Voivodeship, Poland | 2 | 49.06 November | 2.4× |
| PristinaPristina, Kosovo | 1 | 56.78 November | 2.4× |
| Kosovo PoljePristina, Kosovo | 1 | 26.69 November | 2.4× |
| Gorzów WielkopolskiLubusz, Poland | 3 | 34.09 November | 2.4× |
| BydgoszczKujawsko-Pomorskie, Poland | 3 | 39.011 November | 2.4× |
| KościanGreater Poland, Poland | 1 | 43.311 November | 2.4× |
| TrebišovKošice Region, Slovakia | 3 | 39.011 November | 2.4× |
| GjilanGjilan, Kosovo | 1 | 38.610 November | 2.4× |
| PirotCentral Serbia, Serbia | 2 | 80.07 November | 2.4× |
| PartizánskeTrenčín Region, Slovakia | 4 | 26.511 November | 2.4× |
| ValjevoCentral Serbia, Serbia | 3 | 97.49 November | 2.4× |
| BiałystokPodlasie, Poland | 1 | 37.36 November | 2.3× |
| StarachowiceŚwiętokrzyskie, Poland | 1 | 43.75 November | 2.3× |
| PoznańGreater Poland, Poland | 3 | 43.811 November | 2.3× |
| MalackyBratislava Region, Slovakia | 3 | 29.09 November | 2.2× |
| PruszkówMazovia, Poland | 1 | 48.26 November | 2.2× |
| KutnoŁódź Voivodeship, Poland | 1 | 48.15 November | 2.2× |
| PłockMazovia, Poland | 1 | 33.05 November | 2.2× |
| Skarżysko-KamiennaŚwiętokrzyskie, Poland | 1 | 53.56 November | 2.2× |
| LazarevacCentral Serbia, Serbia | 2 | 97.28 November | 2.2× |
| SevlievoGabrovo, Bulgaria | 1 | 26.89 November | 2.1× |
| ĆuprijaCentral Serbia, Serbia | 1 | 59.39 November | 2.1× |
| ElblągWarmia-Masuria, Poland | 1 | 36.511 November | 2.1× |
| PejëPec, Kosovo | 1 | 29.710 November | 2.0× |
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 Germany and Poland
Number 12 of 57 episodes in Germany and Poland since our records began, by cities reached.
- Central Europe, February 2023608
- Central Europe, February and March 2025513
- Central Europe, February 2025503
- Central Europe, January and February 2026498
- Central Europe, March 2025458
- Central Europe, January 2024449
- Central Europe, March 2026442
- Central Europe, January 2025383
- Central Europe, March 2026361
- Central Europe, March 2025333
- Central Europe, February and March 2024264
- Eastern Europe, November 2024260
Bars: cities reached; colour: the level of the episode's highest daily reading. All 57.
Use this page
SmogRank, Eastern Europe, November 2024: 260 cities with PM2.5 at twice their usual or more, 3 to 13 November 2024, smogrank.com/episodes/2024-11-eastern-europe (accessed 3 October 2026).
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.