SmogRank / Episodes / United States

Northern United States and Canada, August and September 2023

For 12 days, from 28 August to 8 September 2023, 82 cities in the United States and Canada had PM2.5 at least twice their usual for the time of year. The worst reading was Prince Albert, Saskatchewan, Canada: 354.0 µg/m³ on 3 September, about 33× its usual 10.8. Ended 8 September.

Likely smoke from firesFires were detected within 300 km of the city on 31% of the counted city-days and smoke was mapped over the city on 100%. Satellites see crop, field and forest fires alike, so this doesn't say which burned.
Cities reached82in 2 countries
Days1228 August to 8 September 2023
Worst day4 September35 cities counted
Furthest above usual33×Prince Albert

Day by day

4 September 35 cities at twice their usual or more
RivertonLanderBozemanRock SpringsLaramieRexburgButteRanchettesIdaho FallsCondaCheyenneFort CollinsPocatelloVernalPrestonGreeleyLongmontSmithfieldRooseveltThorntonMissoulaDenverNorth OgdenKen CarylBountifulColumbia FallsSalt Lake CityMillcreekGrand JunctionWest JordanMagnaCedar HillsHighlandOremHerrimanStansbury parkSpanish ForkTooeleColorado SpringsBrandonTwin FallsCranbrookGarden CitySandpointMeridianCoeur d'AleneCrestonNampaMoscowLewistonPullmanSpokane ValleyMeadSpokaneCedar CityCheneyAirway HeightsCastlegarLa GrandeHurricaneRio RanchoWalla WallaAlbuquerquePendletonMesquiteFinleyPascoTri-CitiesHermistonMoses LakeAmarilloProsserQuincySunnysideBoulder CityLas VegasBrainerdHendersonSpring ValleySummerlin SouthEnterpriseToppenishWenatcheeYakimaEllensburgSaint MichaelShakopeePrinevilleMinneapolisBurnsvilleBlaineApple ValleyThe DallesMadrasSaint PaulRedmondSpanish SpringsBendRenoHood RiverEdmondOklahoma CityCarson CityLawtonMooreVirginiaCloquetTruckeeSouth Lake TahoeRochesterEnumclawIssaquahDuluthSuperiorBellevueAuburnRentonMarysvilleAltamontSeattleWhite CenterShorelineWaterlooGreshamParklandTacomaMount VernonAbbotsfordMill PlainOrchardsSalmon CreekMilwaukieLyndenVancouverBellinghamBremertonPortlandVictorvilleNorth PortlandCanbyAdaRidgefieldAnacortesOak HarborTigardBeavertonLaceySilvertonPortervilleSweet HomeEau ClairePort TownsendStaytonVisaliaClovisWoodburnLangleyAltoonaNorth AuburnLongviewCentraliaChehalisFresnoHillsboroPort CoquitlamParadiseCoquitlamSalemMaderaSheltonStrawberry HillForest GroveFolsomLincolnRancho MurietaLancasterHanfordRosevilleAlbanyBurnabyMcMinnvilleCorcoranLa CrosseMcAlesterEugeneAshlandMercedChicoCottage GroveGridleyDeltaYrekaBakersfieldYuba CityTalentNorth VancouverArden-ArcadeCorvallisDallasMedfordVancouverRichmondWhistlerAndersonWest VancouverReddingRed BluffGaltTurlockSacramentoVictoriaModestoSquamishPort AngelesStocktonHuronMantecaColusaLangfordSpringdaleSanta ClaritaWoodlandWillowsGreenDavisSpringfieldGibsonsGrants PassTracyAberdeenRio VistaNorth CowichanDuncanFillmoreFort SmithMuscatineVacavilleLivermoreNanaimoHarewoodConcordHollisterGilroyDavenportKing CitySan JoseSan LeandroSanta BarbaraMolineCoos BayAtascaderoOaklandRichmondSalinasSan Luis ObispoNipomoRedwood CitySan FranciscoArroyo GrandeSan RafaelClintonOceanoOrcuttBen LomondSebastopolSanta CruzGuadalupeUkiahBarabooCrescent CityBrookingsLompocPort AlberniEurekaThunder BayMadisonCourtenayJerseyvillePeoriaCampbell RiverRockfordUniversity CityArnoldLemaySt. LouisGranite CityEast Saint LouisSpringfieldLittle RockBloomingtonMarionWest MemphisDyersburgBartlettHernandoMiamiTulsaKelownaSaint CloudIowa CityVernonChilliwackAgassizJenksGlenpoolHelena Valley West CentralHelenaEphrataDes MoinesAnkenySaint JosephPonca CityCasperPentictonScottsbluffWichitaKansas CityPrince GeorgeHaysvilleDerbyOlatheGreat FallsKansas CityChanuteRaymoreHopeWatertownWest FargoAberdeenLibertyKearneyDetroit LakesOmahaTopekaEstevanKamloopsBrookingsDrayton ValleySioux FallsCodyBellevuePierreBlairLethbridgeEdsonBeatriceRapid CityLincolnMarshallGrand IslandRed DeerAirdrieWilliams LakeSt. AlbertCalgaryVermillionLewistownSherwood ParkMiles CityMedicine HatFlin FlonLockwoodBillingsGilletteSheridanEdmontonFort SaskatchewanReginaGrande PrairieQuesnelFort McMurrayFort St. JohnSwift CurrentHavreSaskatoonGrand CentrePrince Albert
25 Aug28311 Sep36911
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

Prince AlbertPrince Albert, 25 August: 19.3 µg/m³Prince Albert, 26 August: 16.2 µg/m³Prince Albert, 27 August: 46.2 µg/m³Prince Albert, 28 August: 64.8 µg/m³, 6.0× its usual 10.8Prince Albert, 29 August: 88.3 µg/m³, 8.2× its usual 10.8Prince Albert, 30 August: 52.7 µg/m³, 4.9× its usual 10.8Prince Albert, 31 August: 20.2 µg/m³Prince Albert, 1 September: 98.1 µg/m³, 9.1× its usual 10.8Prince Albert, 2 September: 93.8 µg/m³, 8.7× its usual 10.8Prince Albert, 3 September: 354.0 µg/m³, 33× its usual 10.8Prince Albert, 4 September: 171.0 µg/m³, 16× its usual 10.9Prince Albert, 5 September: 10.6 µg/m³Prince Albert, 6 September: 26.8 µg/m³Prince Albert, 7 September: 32.3 µg/m³Prince Albert, 8 September: 23.0 µg/m³Prince Albert, 9 September: 16.2 µg/m³Prince Albert, 10 September: 14.0 µg/m³Prince Albert, 11 September: 9.2 µg/m³Fort McMurrayFort McMurray, 25 August: 52.6 µg/m³Fort McMurray, 26 August: 80.6 µg/m³Fort McMurray, 27 August: 193.5 µg/m³Fort McMurray, 28 August: 93.9 µg/m³, 6.7× its usual 14.1Fort McMurray, 29 August: 65.7 µg/m³, 4.8× its usual 13.7Fort McMurray, 30 August: 40.3 µg/m³, 3.0× its usual 13.4Fort McMurray, 31 August: 139.0 µg/m³, 11× its usual 13.2Fort McMurray, 1 September: 72.4 µg/m³, 5.5× its usual 13.2Fort McMurray, 2 September: 306.5 µg/m³, 24× its usual 12.9Fort McMurray, 3 September: 259.0 µg/m³, 21× its usual 12.6Fort McMurray, 4 September: 26.2 µg/m³, 2.1× its usual 12.6Fort McMurray, 5 September: 6.0 µg/m³Fort McMurray, 6 September: 21.5 µg/m³Fort McMurray, 7 September: 44.8 µg/m³Fort McMurray, 8 September: 23.4 µg/m³Fort McMurray, 9 September: 25.6 µg/m³Fort McMurray, 10 September: 17.8 µg/m³Fort McMurray, 11 September: 14.0 µg/m³Grand CentreGrand Centre, 25 August: 27.5 µg/m³Grand Centre, 26 August: 16.3 µg/m³Grand Centre, 27 August: 72.5 µg/m³Grand Centre, 28 August: 66.8 µg/m³, 7.0× its usual 9.5Grand Centre, 29 August: 40.8 µg/m³, 4.3× its usual 9.5Grand Centre, 30 August: 40.2 µg/m³, 4.4× its usual 9.1Grand Centre, 31 August: 62.0 µg/m³, 6.8× its usual 9.1Grand Centre, 1 September: 135.0 µg/m³, 15× its usual 9.1Grand Centre, 2 September: 214.0 µg/m³, 24× its usual 9.1Grand Centre, 3 September: 292.0 µg/m³, 32× its usual 9.1Grand Centre, 4 September: 56.1 µg/m³, 6.6× its usual 8.5Grand Centre, 5 September: 4.9 µg/m³Grand Centre, 6 September: 26.7 µg/m³Grand Centre, 7 September: 32.5 µg/m³Grand Centre, 8 September: 11.5 µg/m³Grand Centre, 9 September: 11.3 µg/m³Grand Centre, 10 September: 15.2 µg/m³Grand Centre, 11 September: 13.6 µg/m³SaskatoonSaskatoon, 25 August: 12.9 µg/m³Saskatoon, 26 August: 12.8 µg/m³Saskatoon, 27 August: 33.1 µg/m³Saskatoon, 28 August: 48.0 µg/m³, 4.3× its usual 11.1Saskatoon, 29 August: 48.9 µg/m³, 4.5× its usual 10.9Saskatoon, 30 August: 55.8 µg/m³, 5.4× its usual 10.3Saskatoon, 31 August: 18.5 µg/m³Saskatoon, 1 September: 113.0 µg/m³, 12× its usual 9.4Saskatoon, 2 September: 105.0 µg/m³, 11× its usual 9.4Saskatoon, 3 September: 270.0 µg/m³, 28× its usual 9.7Saskatoon, 4 September: 175.0 µg/m³, 19× its usual 9.4Saskatoon, 5 September: 13.3 µg/m³Saskatoon, 6 September: 32.6 µg/m³Saskatoon, 7 September: 22.8 µg/m³Saskatoon, 8 September: 17.1 µg/m³Saskatoon, 9 September: 15.9 µg/m³Saskatoon, 10 September: 12.5 µg/m³Saskatoon, 11 September: 11.9 µg/m³QuesnelQuesnel, 25 August: 24.9 µg/m³Quesnel, 26 August: 29.2 µg/m³Quesnel, 27 August: 36.6 µg/m³Quesnel, 28 August: 33.6 µg/m³, 3.7× its usual 9.2Quesnel, 29 August: 57.4 µg/m³, 6.4× its usual 8.9Quesnel, 30 August: 29.9 µg/m³, 3.3× its usual 9.1Quesnel, 31 August: 25.2 µg/m³Quesnel, 1 September: 23.4 µg/m³Quesnel, 2 September: 61.1 µg/m³, 6.5× its usual 9.4Quesnel, 3 September: 219.0 µg/m³, 24× its usual 9.2Quesnel, 4 September: 133.0 µg/m³, 15× its usual 8.9Quesnel, 5 September: 63.5 µg/m³, 7.2× its usual 8.8Quesnel, 6 September: 13.6 µg/m³Quesnel, 7 September: 6.5 µg/m³Quesnel, 8 September: 11.9 µg/m³Quesnel, 9 September: 9.5 µg/m³Quesnel, 10 September: 10.0 µg/m³Quesnel, 11 September: 16.7 µg/m³Flin FlonFlin Flon, 25 August: no readingFlin Flon, 26 August: no readingFlin Flon, 27 August: 33.0 µg/m³Flin Flon, 28 August: 63.7 µg/m³, 4.6× its usual 13.8Flin Flon, 29 August: 6.7 µg/m³Flin Flon, 30 August: 14.6 µg/m³Flin Flon, 31 August: 14.9 µg/m³Flin Flon, 1 September: 22.3 µg/m³Flin Flon, 2 September: 120.0 µg/m³, 8.8× its usual 13.6Flin Flon, 3 September: 217.0 µg/m³, 16× its usual 13.8Flin Flon, 4 September: 84.9 µg/m³, 6.1× its usual 14.0Flin Flon, 5 September: 13.2 µg/m³Flin Flon, 6 September: 8.6 µg/m³Flin Flon, 7 September: 14.6 µg/m³Flin Flon, 8 September: 22.7 µg/m³Flin Flon, 9 September: 8.7 µg/m³Flin Flon, 10 September: 3.8 µg/m³Flin Flon, 11 September: 2.8 µg/m³Swift CurrentSwift Current, 25 August: 7.4 µg/m³Swift Current, 26 August: 10.9 µg/m³Swift Current, 27 August: 25.5 µg/m³Swift Current, 28 August: 52.2 µg/m³, 6.4× its usual 8.2Swift Current, 29 August: 49.2 µg/m³, 6.2× its usual 8.0Swift Current, 30 August: 21.0 µg/m³Swift Current, 31 August: 11.6 µg/m³Swift Current, 1 September: 46.8 µg/m³, 6.2× its usual 7.6Swift Current, 2 September: 75.0 µg/m³, 10× its usual 7.4Swift Current, 3 September: 68.3 µg/m³, 9.2× its usual 7.4Swift Current, 4 September: 205.0 µg/m³, 27× its usual 7.6Swift Current, 5 September: 47.3 µg/m³, 6.2× its usual 7.6Swift Current, 6 September: 58.0 µg/m³Swift Current, 7 September: 21.6 µg/m³Swift Current, 8 September: 8.9 µg/m³Swift Current, 9 September: 6.0 µg/m³Swift Current, 10 September: 8.3 µg/m³Swift Current, 11 September: 10.2 µg/m³EdmontonEdmonton, 25 August: 79.4 µg/m³Edmonton, 26 August: 25.5 µg/m³Edmonton, 27 August: 56.6 µg/m³Edmonton, 28 August: 61.9 µg/m³, 4.8× its usual 13.0Edmonton, 29 August: 46.6 µg/m³, 3.8× its usual 12.3Edmonton, 30 August: 47.0 µg/m³, 4.1× its usual 11.6Edmonton, 31 August: 51.9 µg/m³, 4.6× its usual 11.4Edmonton, 1 September: 76.3 µg/m³, 6.7× its usual 11.4Edmonton, 2 September: 121.0 µg/m³, 11× its usual 11.4Edmonton, 3 September: 201.0 µg/m³, 18× its usual 11.3Edmonton, 4 September: 103.0 µg/m³, 9.0× its usual 11.4Edmonton, 5 September: 62.7 µg/m³, 5.5× its usual 11.3Edmonton, 6 September: 63.2 µg/m³Edmonton, 7 September: 25.1 µg/m³Edmonton, 8 September: 20.4 µg/m³Edmonton, 9 September: 21.0 µg/m³Edmonton, 10 September: 11.6 µg/m³Edmonton, 11 September: 11.0 µg/m³Fort SaskatchewanFort Saskatchewan, 25 August: 67.9 µg/m³Fort Saskatchewan, 26 August: 18.2 µg/m³Fort Saskatchewan, 27 August: 41.7 µg/m³Fort Saskatchewan, 28 August: 44.1 µg/m³, 4.4× its usual 10.1Fort Saskatchewan, 29 August: 33.4 µg/m³, 3.4× its usual 9.8Fort Saskatchewan, 30 August: 34.1 µg/m³, 3.6× its usual 9.6Fort Saskatchewan, 31 August: 50.1 µg/m³, 5.3× its usual 9.5Fort Saskatchewan, 1 September: 71.2 µg/m³, 7.5× its usual 9.5Fort Saskatchewan, 2 September: 113.0 µg/m³, 12× its usual 9.6Fort Saskatchewan, 3 September: 178.0 µg/m³, 19× its usual 9.6Fort Saskatchewan, 4 September: 84.1 µg/m³, 8.8× its usual 9.6Fort Saskatchewan, 5 September: 44.6 µg/m³, 4.6× its usual 9.6Fort Saskatchewan, 6 September: 50.8 µg/m³Fort Saskatchewan, 7 September: 17.4 µg/m³Fort Saskatchewan, 8 September: 13.2 µg/m³Fort Saskatchewan, 9 September: 13.8 µg/m³Fort Saskatchewan, 10 September: 9.1 µg/m³Fort Saskatchewan, 11 September: 8.1 µg/m³ReginaRegina, 25 August: 17.0 µg/m³Regina, 26 August: 17.9 µg/m³Regina, 27 August: 31.8 µg/m³Regina, 28 August: 74.1 µg/m³, 7.3× its usual 10.2Regina, 29 August: 68.8 µg/m³, 6.9× its usual 9.9Regina, 30 August: 60.0 µg/m³, 6.3× its usual 9.5Regina, 31 August: 10.8 µg/m³Regina, 1 September: 59.9 µg/m³, 6.3× its usual 9.5Regina, 2 September: 81.8 µg/m³, 8.8× its usual 9.3Regina, 3 September: 108.0 µg/m³, 12× its usual 9.0Regina, 4 September: 176.0 µg/m³, 20× its usual 9.0Regina, 5 September: 38.2 µg/m³, 4.2× its usual 9.0Regina, 6 September: 58.0 µg/m³Regina, 7 September: 40.7 µg/m³Regina, 8 September: 20.2 µg/m³Regina, 9 September: 15.2 µg/m³Regina, 10 September: 21.7 µg/m³Regina, 11 September: 15.8 µg/m³Grande PrairieGrande Prairie, 25 August: 44.0 µg/m³Grande Prairie, 26 August: 38.6 µg/m³Grande Prairie, 27 August: 48.8 µg/m³Grande Prairie, 28 August: 81.8 µg/m³, 10.0× its usual 8.2Grande Prairie, 29 August: 110.0 µg/m³, 14× its usual 8.1Grande Prairie, 30 August: 102.0 µg/m³, 13× its usual 8.1Grande Prairie, 31 August: 33.8 µg/m³Grande Prairie, 1 September: 28.6 µg/m³, 3.5× its usual 8.2Grande Prairie, 2 September: 58.7 µg/m³, 7.2× its usual 8.2Grande Prairie, 3 September: 160.0 µg/m³, 20× its usual 8.1Grande Prairie, 4 September: 33.8 µg/m³, 4.3× its usual 7.8Grande Prairie, 5 September: 29.5 µg/m³, 3.9× its usual 7.6Grande Prairie, 6 September: 39.3 µg/m³Grande Prairie, 7 September: 11.5 µg/m³Grande Prairie, 8 September: 17.0 µg/m³Grande Prairie, 9 September: 25.5 µg/m³Grande Prairie, 10 September: 23.5 µg/m³Grande Prairie, 11 September: 44.6 µg/m³Fort St. JohnFort St. John, 25 August: 45.1 µg/m³Fort St. John, 26 August: 43.7 µg/m³Fort St. John, 27 August: 46.8 µg/m³Fort St. John, 28 August: 67.1 µg/m³, 11× its usual 6.2Fort St. John, 29 August: 80.7 µg/m³, 13× its usual 6.1Fort St. John, 30 August: 69.8 µg/m³, 11× its usual 6.1Fort St. John, 31 August: 21.7 µg/m³Fort St. John, 1 September: 66.1 µg/m³, 11× its usual 6.2Fort St. John, 2 September: 155.0 µg/m³, 25× its usual 6.1Fort St. John, 3 September: 136.0 µg/m³, 22× its usual 6.1Fort St. John, 4 September: 14.1 µg/m³Fort St. John, 5 September: 38.1 µg/m³, 6.2× its usual 6.1Fort St. John, 6 September: 42.7 µg/m³Fort St. John, 7 September: 14.7 µg/m³Fort St. John, 8 September: 16.6 µg/m³Fort St. John, 9 September: 13.0 µg/m³Fort St. John, 10 September: 15.8 µg/m³Fort St. John, 11 September: 104.0 µg/m³Sherwood ParkSherwood Park, 25 August: 44.3 µg/m³Sherwood Park, 26 August: 10.4 µg/m³Sherwood Park, 27 August: 28.5 µg/m³Sherwood Park, 28 August: 30.5 µg/m³, 3.6× its usual 8.5Sherwood Park, 29 August: 21.0 µg/m³Sherwood Park, 30 August: 20.8 µg/m³Sherwood Park, 31 August: 26.4 µg/m³, 3.3× its usual 8.1Sherwood Park, 1 September: 47.1 µg/m³, 5.9× its usual 8.0Sherwood Park, 2 September: 61.1 µg/m³, 7.6× its usual 8.0Sherwood Park, 3 September: 114.0 µg/m³, 14× its usual 8.0Sherwood Park, 4 September: 50.0 µg/m³, 6.2× its usual 8.1Sherwood Park, 5 September: 33.8 µg/m³, 4.2× its usual 8.1Sherwood Park, 6 September: 29.4 µg/m³Sherwood Park, 7 September: 11.4 µg/m³Sherwood Park, 8 September: 8.5 µg/m³Sherwood Park, 9 September: 11.1 µg/m³Sherwood Park, 10 September: 6.7 µg/m³Sherwood Park, 11 September: no readingRed DeerRed Deer, 25 August: 25.9 µg/m³Red Deer, 26 August: 15.1 µg/m³Red Deer, 27 August: 29.8 µg/m³Red Deer, 28 August: 33.7 µg/m³, 3.3× its usual 10.3Red Deer, 29 August: 28.6 µg/m³, 2.8× its usual 10.1Red Deer, 30 August: 27.5 µg/m³, 2.8× its usual 9.7Red Deer, 31 August: 44.0 µg/m³, 4.5× its usual 9.7Red Deer, 1 September: 40.3 µg/m³, 4.2× its usual 9.7Red Deer, 2 September: 49.0 µg/m³, 5.2× its usual 9.5Red Deer, 3 September: 111.7 µg/m³, 12× its usual 9.7Red Deer, 4 September: 107.4 µg/m³, 11× its usual 10.0Red Deer, 5 September: 72.4 µg/m³, 7.2× its usual 10.0Red Deer, 6 September: 23.4 µg/m³Red Deer, 7 September: 8.3 µg/m³Red Deer, 8 September: 12.3 µg/m³Red Deer, 9 September: 10.4 µg/m³Red Deer, 10 September: 8.8 µg/m³Red Deer, 11 September: 9.5 µg/m³Medicine HatMedicine Hat, 25 August: 11.9 µg/m³Medicine Hat, 26 August: 7.3 µg/m³Medicine Hat, 27 August: 19.7 µg/m³Medicine Hat, 28 August: 29.0 µg/m³, 3.5× its usual 8.2Medicine Hat, 29 August: 21.0 µg/m³Medicine Hat, 30 August: 1.7 µg/m³Medicine Hat, 31 August: 21.5 µg/m³Medicine Hat, 1 September: 15.0 µg/m³Medicine Hat, 2 September: 7.4 µg/m³Medicine Hat, 3 September: 24.0 µg/m³Medicine Hat, 4 September: 109.0 µg/m³, 15× its usual 7.3Medicine Hat, 5 September: 78.6 µg/m³, 11× its usual 7.3Medicine Hat, 6 September: 32.0 µg/m³Medicine Hat, 7 September: 6.9 µg/m³Medicine Hat, 8 September: 7.2 µg/m³Medicine Hat, 9 September: 5.4 µg/m³Medicine Hat, 10 September: 5.3 µg/m³Medicine Hat, 11 September: 4.3 µg/m³St. AlbertSt. Albert, 25 August: 50.1 µg/m³St. Albert, 26 August: 13.5 µg/m³St. Albert, 27 August: 28.7 µg/m³St. Albert, 28 August: 30.1 µg/m³, 3.4× its usual 8.8St. Albert, 29 August: 23.1 µg/m³St. Albert, 30 August: 23.8 µg/m³St. Albert, 31 August: 28.4 µg/m³, 3.5× its usual 8.2St. Albert, 1 September: 45.4 µg/m³, 5.5× its usual 8.2St. Albert, 2 September: 59.6 µg/m³, 7.3× its usual 8.2St. Albert, 3 September: 104.0 µg/m³, 13× its usual 8.1St. Albert, 4 September: 51.1 µg/m³, 6.2× its usual 8.2St. Albert, 5 September: 36.8 µg/m³, 4.5× its usual 8.2St. Albert, 6 September: 30.3 µg/m³St. Albert, 7 September: 10.5 µg/m³St. Albert, 8 September: 9.1 µg/m³St. Albert, 9 September: 13.4 µg/m³St. Albert, 10 September: 9.9 µg/m³St. Albert, 11 September: 7.7 µg/m³EstevanEstevan, 25 August: 16.3 µg/m³Estevan, 26 August: 15.0 µg/m³Estevan, 27 August: 20.8 µg/m³Estevan, 28 August: 58.1 µg/m³, 5.2× its usual 11.1Estevan, 29 August: 76.6 µg/m³, 6.9× its usual 11.1Estevan, 30 August: 59.7 µg/m³, 5.4× its usual 11.1Estevan, 31 August: 8.7 µg/m³Estevan, 1 September: 41.5 µg/m³, 3.8× its usual 11.0Estevan, 2 September: 23.6 µg/m³Estevan, 3 September: 88.4 µg/m³, 8.3× its usual 10.6Estevan, 4 September: 83.9 µg/m³, 8.0× its usual 10.5Estevan, 5 September: 62.5 µg/m³, 5.9× its usual 10.6Estevan, 6 September: 34.8 µg/m³Estevan, 7 September: 58.4 µg/m³Estevan, 8 September: 20.3 µg/m³Estevan, 9 September: 21.1 µg/m³Estevan, 10 September: 18.2 µg/m³Estevan, 11 September: 11.5 µg/m³KamloopsKamloops, 25 August: 31.6 µg/m³Kamloops, 26 August: 30.4 µg/m³Kamloops, 27 August: 34.4 µg/m³Kamloops, 28 August: 54.8 µg/m³, 5.6× its usual 9.7Kamloops, 29 August: 83.3 µg/m³, 8.5× its usual 9.8Kamloops, 30 August: 18.7 µg/m³Kamloops, 31 August: 15.1 µg/m³Kamloops, 1 September: 13.2 µg/m³Kamloops, 2 September: 19.5 µg/m³Kamloops, 3 September: 53.5 µg/m³, 5.5× its usual 9.8Kamloops, 4 September: 53.3 µg/m³, 5.4× its usual 9.9Kamloops, 5 September: 6.2 µg/m³Kamloops, 6 September: 9.5 µg/m³Kamloops, 7 September: 5.0 µg/m³Kamloops, 8 September: 8.4 µg/m³Kamloops, 9 September: 11.3 µg/m³Kamloops, 10 September: 13.9 µg/m³Kamloops, 11 September: 8.9 µg/m³Drayton ValleyDrayton Valley, 25 August: 19.3 µg/m³Drayton Valley, 26 August: 19.3 µg/m³Drayton Valley, 27 August: 31.2 µg/m³Drayton Valley, 28 August: 30.4 µg/m³, 3.5× its usual 8.8Drayton Valley, 29 August: 21.9 µg/m³Drayton Valley, 30 August: 41.3 µg/m³, 5.0× its usual 8.2Drayton Valley, 31 August: 24.2 µg/m³Drayton Valley, 1 September: 30.0 µg/m³, 3.7× its usual 8.1Drayton Valley, 2 September: 19.5 µg/m³Drayton Valley, 3 September: 72.4 µg/m³, 8.9× its usual 8.1Drayton Valley, 4 September: 61.3 µg/m³, 7.5× its usual 8.2Drayton Valley, 5 September: 60.8 µg/m³, 7.6× its usual 8.0Drayton Valley, 6 September: 21.1 µg/m³Drayton Valley, 7 September: 5.3 µg/m³Drayton Valley, 8 September: 8.8 µg/m³Drayton Valley, 9 September: 9.4 µg/m³Drayton Valley, 10 September: 7.9 µg/m³Drayton Valley, 11 September: 8.1 µg/m³EdsonEdson, 25 August: 11.3 µg/m³Edson, 26 August: 17.6 µg/m³Edson, 27 August: 25.3 µg/m³Edson, 28 August: 26.6 µg/m³, 3.5× its usual 7.6Edson, 29 August: 26.2 µg/m³, 3.7× its usual 7.1Edson, 30 August: 53.2 µg/m³, 7.5× its usual 7.1Edson, 31 August: 24.9 µg/m³Edson, 1 September: 19.5 µg/m³Edson, 2 September: 21.2 µg/m³Edson, 3 September: 70.7 µg/m³, 10× its usual 7.0Edson, 4 September: 63.6 µg/m³, 9.1× its usual 7.0Edson, 5 September: 54.7 µg/m³, 7.8× its usual 7.0Edson, 6 September: 13.7 µg/m³Edson, 7 September: 3.5 µg/m³Edson, 8 September: 7.0 µg/m³Edson, 9 September: 8.3 µg/m³Edson, 10 September: 8.7 µg/m³Edson, 11 September: 8.1 µg/m³HopeHope, 25 August: 56.0 µg/m³Hope, 26 August: 36.4 µg/m³Hope, 27 August: 93.2 µg/m³Hope, 28 August: 44.4 µg/m³, 7.4× its usual 6.0Hope, 29 August: 9.5 µg/m³Hope, 30 August: 4.1 µg/m³Hope, 31 August: 8.8 µg/m³Hope, 1 September: 8.4 µg/m³Hope, 2 September: 10.8 µg/m³Hope, 3 September: 9.9 µg/m³Hope, 4 September: 3.8 µg/m³Hope, 5 September: 5.6 µg/m³Hope, 6 September: 5.1 µg/m³Hope, 7 September: 5.9 µg/m³Hope, 8 September: 7.0 µg/m³Hope, 9 September: 10.5 µg/m³Hope, 10 September: 8.6 µg/m³Hope, 11 September: 6.9 µg/m³CalgaryCalgary, 25 August: 17.5 µg/m³Calgary, 26 August: 16.9 µg/m³Calgary, 27 August: 21.4 µg/m³Calgary, 28 August: 23.2 µg/m³Calgary, 29 August: 22.0 µg/m³Calgary, 30 August: 25.0 µg/m³, 2.5× its usual 10.1Calgary, 31 August: 42.6 µg/m³, 4.1× its usual 10.3Calgary, 1 September: 23.7 µg/m³Calgary, 2 September: 10.7 µg/m³Calgary, 3 September: 62.7 µg/m³, 6.0× its usual 10.5Calgary, 4 September: 143.0 µg/m³, 13× its usual 11.2Calgary, 5 September: 82.9 µg/m³, 7.4× its usual 11.2Calgary, 6 September: 16.8 µg/m³Calgary, 7 September: 8.3 µg/m³Calgary, 8 September: 9.8 µg/m³Calgary, 9 September: 10.3 µg/m³Calgary, 10 September: 8.5 µg/m³Calgary, 11 September: 10.1 µg/m³AirdrieAirdrie, 25 August: 12.9 µg/m³Airdrie, 26 August: 13.6 µg/m³Airdrie, 27 August: 17.9 µg/m³Airdrie, 28 August: 17.4 µg/m³Airdrie, 29 August: 17.4 µg/m³Airdrie, 30 August: 17.8 µg/m³Airdrie, 31 August: 30.5 µg/m³, 4.2× its usual 7.3Airdrie, 1 September: 17.3 µg/m³Airdrie, 2 September: 6.5 µg/m³Airdrie, 3 September: 58.5 µg/m³, 7.9× its usual 7.4Airdrie, 4 September: 93.7 µg/m³, 12× its usual 7.6Airdrie, 5 September: 50.9 µg/m³, 6.8× its usual 7.5Airdrie, 6 September: 9.5 µg/m³Airdrie, 7 September: 6.2 µg/m³Airdrie, 8 September: 8.0 µg/m³Airdrie, 9 September: 8.4 µg/m³Airdrie, 10 September: 7.7 µg/m³Airdrie, 11 September: 8.6 µg/m³LethbridgeLethbridge, 25 August: 11.5 µg/m³Lethbridge, 26 August: 8.5 µg/m³Lethbridge, 27 August: 13.0 µg/m³Lethbridge, 28 August: 12.3 µg/m³Lethbridge, 29 August: 14.0 µg/m³Lethbridge, 30 August: 4.5 µg/m³Lethbridge, 31 August: 25.8 µg/m³, 3.1× its usual 8.3Lethbridge, 1 September: 14.1 µg/m³Lethbridge, 2 September: 3.4 µg/m³Lethbridge, 3 September: 18.1 µg/m³Lethbridge, 4 September: 83.9 µg/m³, 9.8× its usual 8.6Lethbridge, 5 September: 47.3 µg/m³, 5.6× its usual 8.5Lethbridge, 6 September: 14.2 µg/m³Lethbridge, 7 September: 3.5 µg/m³Lethbridge, 8 September: 11.4 µg/m³Lethbridge, 9 September: 8.1 µg/m³Lethbridge, 10 September: 5.3 µg/m³Lethbridge, 11 September: 5.6 µg/m³HavreHavre, 25 August: 6.3 µg/m³Havre, 26 August: 6.9 µg/m³Havre, 27 August: 9.0 µg/m³Havre, 28 August: 20.4 µg/m³Havre, 29 August: 24.4 µg/m³Havre, 30 August: 5.1 µg/m³Havre, 31 August: 23.2 µg/m³Havre, 1 September: 25.2 µg/m³, 5.0× its usual 5.0Havre, 2 September: 11.0 µg/m³Havre, 3 September: 4.7 µg/m³Havre, 4 September: 136.0 µg/m³, 27× its usual 4.9Havre, 5 September: 102.0 µg/m³, 20× its usual 4.9Havre, 6 September: 37.4 µg/m³Havre, 7 September: 9.5 µg/m³Havre, 8 September: 6.7 µg/m³Havre, 9 September: 5.8 µg/m³Havre, 10 September: 5.6 µg/m³Havre, 11 September: 5.2 µg/m³Prince GeorgePrince George, 25 August: no readingPrince George, 26 August: no readingPrince George, 27 August: no readingPrince George, 28 August: no readingPrince George, 29 August: no readingPrince George, 30 August: no readingPrince George, 31 August: 16.0 µg/m³Prince George, 1 September: 40.9 µg/m³, 4.0× its usual 10.3Prince George, 2 September: 49.9 µg/m³, 5.0× its usual 10.0Prince George, 3 September: 35.3 µg/m³, 3.5× its usual 10.0Prince George, 4 September: 64.0 µg/m³, 6.4× its usual 10.0Prince George, 5 September: 45.3 µg/m³, 4.6× its usual 9.9Prince George, 6 September: 29.9 µg/m³Prince George, 7 September: 10.2 µg/m³Prince George, 8 September: 11.8 µg/m³Prince George, 9 September: 11.4 µg/m³Prince George, 10 September: 13.4 µg/m³Prince George, 11 September: 47.8 µg/m³Williams LakeWilliams Lake, 25 August: 9.8 µg/m³Williams Lake, 26 August: 12.8 µg/m³Williams Lake, 27 August: 13.5 µg/m³Williams Lake, 28 August: 9.7 µg/m³Williams Lake, 29 August: 12.4 µg/m³Williams Lake, 30 August: 9.6 µg/m³Williams Lake, 31 August: 6.0 µg/m³Williams Lake, 1 September: 12.6 µg/m³Williams Lake, 2 September: 14.6 µg/m³Williams Lake, 3 September: 63.9 µg/m³, 13× its usual 4.8Williams Lake, 4 September: 52.4 µg/m³, 10× its usual 4.8Williams Lake, 5 September: 23.7 µg/m³Williams Lake, 6 September: 6.9 µg/m³Williams Lake, 7 September: 1.3 µg/m³Williams Lake, 8 September: 2.5 µg/m³Williams Lake, 9 September: 3.6 µg/m³Williams Lake, 10 September: 4.2 µg/m³Williams Lake, 11 September: 3.8 µg/m³BillingsBillings, 25 August: 11.9 µg/m³Billings, 26 August: 7.8 µg/m³Billings, 27 August: 5.4 µg/m³Billings, 28 August: 5.4 µg/m³Billings, 29 August: 5.5 µg/m³Billings, 30 August: 6.6 µg/m³Billings, 31 August: 3.7 µg/m³Billings, 1 September: 8.2 µg/m³Billings, 2 September: 4.1 µg/m³Billings, 3 September: 3.4 µg/m³Billings, 4 September: 57.6 µg/m³, 8.2× its usual 7.0Billings, 5 September: 115.0 µg/m³, 17× its usual 6.9Billings, 6 September: 29.4 µg/m³Billings, 7 September: 5.9 µg/m³Billings, 8 September: 8.5 µg/m³Billings, 9 September: 6.2 µg/m³Billings, 10 September: 7.3 µg/m³Billings, 11 September: 7.0 µg/m³LockwoodLockwood, 25 August: 11.9 µg/m³Lockwood, 26 August: 7.8 µg/m³Lockwood, 27 August: 5.4 µg/m³Lockwood, 28 August: 5.4 µg/m³Lockwood, 29 August: 5.5 µg/m³Lockwood, 30 August: 6.6 µg/m³Lockwood, 31 August: 3.7 µg/m³Lockwood, 1 September: 8.2 µg/m³Lockwood, 2 September: 4.1 µg/m³Lockwood, 3 September: 3.4 µg/m³Lockwood, 4 September: 57.6 µg/m³, 8.2× its usual 7.0Lockwood, 5 September: 115.0 µg/m³, 17× its usual 6.9Lockwood, 6 September: 29.4 µg/m³Lockwood, 7 September: 5.9 µg/m³Lockwood, 8 September: 8.5 µg/m³Lockwood, 9 September: 6.2 µg/m³Lockwood, 10 September: 7.3 µg/m³Lockwood, 11 September: 7.0 µg/m³Miles CityMiles City, 25 August: 9.6 µg/m³Miles City, 26 August: 9.5 µg/m³Miles City, 27 August: 9.5 µg/m³Miles City, 28 August: 13.9 µg/m³Miles City, 29 August: 18.2 µg/m³Miles City, 30 August: 20.1 µg/m³Miles City, 31 August: 9.8 µg/m³Miles City, 1 September: 17.5 µg/m³Miles City, 2 September: 9.0 µg/m³Miles City, 3 September: 7.4 µg/m³Miles City, 4 September: 79.5 µg/m³, 10× its usual 7.6Miles City, 5 September: 111.0 µg/m³, 14× its usual 7.7Miles City, 6 September: 52.8 µg/m³Miles City, 7 September: 30.2 µg/m³Miles City, 8 September: 15.0 µg/m³Miles City, 9 September: 12.9 µg/m³Miles City, 10 September: 10.4 µg/m³Miles City, 11 September: 8.6 µg/m³LewistownLewistown, 25 August: 11.4 µg/m³Lewistown, 26 August: 8.0 µg/m³Lewistown, 27 August: 6.8 µg/m³Lewistown, 28 August: 7.6 µg/m³Lewistown, 29 August: 6.1 µg/m³Lewistown, 30 August: 6.5 µg/m³Lewistown, 31 August: 11.1 µg/m³Lewistown, 1 September: 17.1 µg/m³Lewistown, 2 September: 6.4 µg/m³Lewistown, 3 September: 5.9 µg/m³Lewistown, 4 September: 70.4 µg/m³, 11× its usual 6.5Lewistown, 5 September: 93.2 µg/m³, 14× its usual 6.6Lewistown, 6 September: no readingLewistown, 7 September: no readingLewistown, 8 September: 4.4 µg/m³Lewistown, 9 September: 3.8 µg/m³Lewistown, 10 September: 4.5 µg/m³Lewistown, 11 September: 5.5 µg/m³SheridanSheridan, 25 August: 9.2 µg/m³Sheridan, 26 August: 5.0 µg/m³Sheridan, 27 August: 3.8 µg/m³Sheridan, 28 August: 3.1 µg/m³Sheridan, 29 August: 2.9 µg/m³Sheridan, 30 August: 7.0 µg/m³Sheridan, 31 August: 7.1 µg/m³Sheridan, 1 September: 3.4 µg/m³Sheridan, 2 September: 3.0 µg/m³Sheridan, 3 September: 2.2 µg/m³Sheridan, 4 September: 30.3 µg/m³, 5.8× its usual 5.2Sheridan, 5 September: 91.5 µg/m³, 18× its usual 5.2Sheridan, 6 September: 21.0 µg/m³Sheridan, 7 September: 3.1 µg/m³Sheridan, 8 September: 3.6 µg/m³Sheridan, 9 September: 4.2 µg/m³Sheridan, 10 September: 3.5 µg/m³Sheridan, 11 September: 2.3 µg/m³GilletteGillette, 25 August: 11.1 µg/m³Gillette, 26 August: 8.9 µg/m³Gillette, 27 August: 7.5 µg/m³Gillette, 28 August: 6.4 µg/m³Gillette, 29 August: 7.7 µg/m³Gillette, 30 August: 6.9 µg/m³Gillette, 31 August: 6.0 µg/m³Gillette, 1 September: 6.0 µg/m³Gillette, 2 September: 3.9 µg/m³Gillette, 3 September: 4.3 µg/m³Gillette, 4 September: 26.9 µg/m³, 5.2× its usual 5.2Gillette, 5 September: 90.4 µg/m³, 17× its usual 5.2Gillette, 6 September: 43.7 µg/m³Gillette, 7 September: 9.9 µg/m³Gillette, 8 September: 9.5 µg/m³Gillette, 9 September: 11.1 µg/m³Gillette, 10 September: 4.5 µg/m³Gillette, 11 September: 4.4 µg/m³Great FallsGreat Falls, 25 August: 12.3 µg/m³Great Falls, 26 August: 11.6 µg/m³Great Falls, 27 August: 15.1 µg/m³Great Falls, 28 August: 16.3 µg/m³Great Falls, 29 August: 12.5 µg/m³Great Falls, 30 August: 8.8 µg/m³Great Falls, 31 August: 12.3 µg/m³Great Falls, 1 September: 21.4 µg/m³Great Falls, 2 September: 15.8 µg/m³Great Falls, 3 September: 10.3 µg/m³Great Falls, 4 September: 78.1 µg/m³, 6.7× its usual 11.7Great Falls, 5 September: 57.5 µg/m³, 4.9× its usual 11.7Great Falls, 6 September: 11.9 µg/m³Great Falls, 7 September: 10.2 µg/m³Great Falls, 8 September: 10.6 µg/m³Great Falls, 9 September: 9.5 µg/m³Great Falls, 10 September: 10.4 µg/m³Great Falls, 11 September: 12.1 µg/m³Rapid CityRapid City, 25 August: 29.9 µg/m³Rapid City, 26 August: 11.5 µg/m³Rapid City, 27 August: 11.6 µg/m³Rapid City, 28 August: 10.3 µg/m³Rapid City, 29 August: 13.9 µg/m³Rapid City, 30 August: 11.6 µg/m³Rapid City, 31 August: 8.3 µg/m³Rapid City, 1 September: 15.3 µg/m³Rapid City, 2 September: 7.0 µg/m³Rapid City, 3 September: 6.7 µg/m³Rapid City, 4 September: 8.8 µg/m³Rapid City, 5 September: 73.6 µg/m³, 10× its usual 7.1Rapid City, 6 September: 67.6 µg/m³Rapid City, 7 September: 29.3 µg/m³Rapid City, 8 September: 12.6 µg/m³Rapid City, 9 September: 17.0 µg/m³Rapid City, 10 September: 11.8 µg/m³Rapid City, 11 September: 7.3 µg/m³West FargoWest Fargo, 25 August: 9.0 µg/m³West Fargo, 26 August: 7.5 µg/m³West Fargo, 27 August: 7.2 µg/m³West Fargo, 28 August: 15.3 µg/m³West Fargo, 29 August: 41.6 µg/m³West Fargo, 30 August: 34.9 µg/m³West Fargo, 31 August: 22.3 µg/m³West Fargo, 1 September: 18.7 µg/m³West Fargo, 2 September: 16.6 µg/m³West Fargo, 3 September: 23.7 µg/m³West Fargo, 4 September: 11.6 µg/m³West Fargo, 5 September: 51.7 µg/m³, 7.5× its usual 6.9West Fargo, 6 September: 36.4 µg/m³, 5.2× its usual 7.0West Fargo, 7 September: 32.2 µg/m³, 4.5× its usual 7.1West Fargo, 8 September: 23.7 µg/m³West Fargo, 9 September: 18.7 µg/m³West Fargo, 10 September: 20.3 µg/m³West Fargo, 11 September: 11.0 µg/m³PierrePierre, 25 August: 7.3 µg/m³Pierre, 26 August: 7.9 µg/m³Pierre, 27 August: 7.1 µg/m³Pierre, 28 August: 7.8 µg/m³Pierre, 29 August: 29.7 µg/m³Pierre, 30 August: 33.1 µg/m³Pierre, 31 August: 14.2 µg/m³Pierre, 1 September: 11.2 µg/m³Pierre, 2 September: 8.8 µg/m³Pierre, 3 September: 4.5 µg/m³Pierre, 4 September: 2.6 µg/m³Pierre, 5 September: 49.0 µg/m³, 9.6× its usual 5.1Pierre, 6 September: no readingPierre, 7 September: no readingPierre, 8 September: 26.8 µg/m³, 5.4× its usual 5.0Pierre, 9 September: 14.1 µg/m³Pierre, 10 September: 10.3 µg/m³Pierre, 11 September: 9.1 µg/m³CodyCody, 25 August: 9.3 µg/m³Cody, 26 August: 6.3 µg/m³Cody, 27 August: 3.8 µg/m³Cody, 28 August: 2.9 µg/m³Cody, 29 August: 3.7 µg/m³Cody, 30 August: 5.7 µg/m³Cody, 31 August: 3.2 µg/m³Cody, 1 September: 3.2 µg/m³Cody, 2 September: 1.8 µg/m³Cody, 3 September: 3.5 µg/m³Cody, 4 September: 7.4 µg/m³Cody, 5 September: 45.8 µg/m³, 9.2× its usual 3.7Cody, 6 September: 3.6 µg/m³Cody, 7 September: 2.8 µg/m³Cody, 8 September: 3.9 µg/m³Cody, 9 September: 3.5 µg/m³Cody, 10 September: 3.5 µg/m³Cody, 11 September: 3.7 µg/m³TopekaTopeka, 25 August: 13.8 µg/m³Topeka, 26 August: 7.5 µg/m³Topeka, 27 August: 11.7 µg/m³Topeka, 28 August: 10.7 µg/m³Topeka, 29 August: 16.7 µg/m³Topeka, 30 August: 22.7 µg/m³Topeka, 31 August: 12.5 µg/m³Topeka, 1 September: 9.0 µg/m³Topeka, 2 September: 11.4 µg/m³Topeka, 3 September: 13.0 µg/m³Topeka, 4 September: 14.3 µg/m³Topeka, 5 September: 12.6 µg/m³Topeka, 6 September: 71.8 µg/m³, 8.3× its usual 8.6Topeka, 7 September: 72.4 µg/m³, 8.2× its usual 8.8Topeka, 8 September: 29.5 µg/m³, 3.3× its usual 8.9Topeka, 9 September: 17.6 µg/m³Topeka, 10 September: 12.6 µg/m³Topeka, 11 September: 8.9 µg/m³BeatriceBeatrice, 25 August: 11.0 µg/m³Beatrice, 26 August: 11.5 µg/m³Beatrice, 27 August: 6.8 µg/m³Beatrice, 28 August: 5.6 µg/m³Beatrice, 29 August: 13.9 µg/m³Beatrice, 30 August: 17.8 µg/m³Beatrice, 31 August: 14.1 µg/m³Beatrice, 1 September: 10.0 µg/m³Beatrice, 2 September: 12.8 µg/m³Beatrice, 3 September: 11.6 µg/m³Beatrice, 4 September: 11.3 µg/m³Beatrice, 5 September: 16.2 µg/m³Beatrice, 6 September: 72.2 µg/m³, 10× its usual 7.1Beatrice, 7 September: 53.2 µg/m³, 7.4× its usual 7.2Beatrice, 8 September: 26.3 µg/m³, 3.6× its usual 7.3Beatrice, 9 September: 15.0 µg/m³Beatrice, 10 September: 10.8 µg/m³Beatrice, 11 September: 9.5 µg/m³Grand IslandGrand Island, 25 August: 9.4 µg/m³Grand Island, 26 August: 8.8 µg/m³Grand Island, 27 August: 7.4 µg/m³Grand Island, 28 August: 7.0 µg/m³Grand Island, 29 August: 13.0 µg/m³Grand Island, 30 August: 26.5 µg/m³Grand Island, 31 August: 14.1 µg/m³Grand Island, 1 September: 14.2 µg/m³Grand Island, 2 September: 11.9 µg/m³Grand Island, 3 September: 12.3 µg/m³Grand Island, 4 September: 13.0 µg/m³Grand Island, 5 September: 17.5 µg/m³Grand Island, 6 September: 71.0 µg/m³, 11× its usual 6.4Grand Island, 7 September: 59.5 µg/m³, 9.0× its usual 6.6Grand Island, 8 September: 34.0 µg/m³, 4.9× its usual 6.9Grand Island, 9 September: 15.0 µg/m³Grand Island, 10 September: 13.1 µg/m³Grand Island, 11 September: 10.1 µg/m³MarshallMarshall, 25 August: 13.1 µg/m³Marshall, 26 August: 8.5 µg/m³Marshall, 27 August: 7.9 µg/m³Marshall, 28 August: 14.4 µg/m³Marshall, 29 August: 42.5 µg/m³Marshall, 30 August: 47.7 µg/m³Marshall, 31 August: 24.4 µg/m³Marshall, 1 September: 14.8 µg/m³Marshall, 2 September: 16.8 µg/m³Marshall, 3 September: 15.0 µg/m³Marshall, 4 September: 15.2 µg/m³Marshall, 5 September: 22.2 µg/m³Marshall, 6 September: 70.4 µg/m³, 11× its usual 6.7Marshall, 7 September: 37.4 µg/m³, 5.6× its usual 6.7Marshall, 8 September: 29.3 µg/m³, 4.4× its usual 6.7Marshall, 9 September: 30.2 µg/m³Marshall, 10 September: 19.0 µg/m³Marshall, 11 September: 17.3 µg/m³LincolnLincoln, 25 August: 9.6 µg/m³Lincoln, 26 August: 6.4 µg/m³Lincoln, 27 August: 6.1 µg/m³Lincoln, 28 August: 6.1 µg/m³Lincoln, 29 August: 17.4 µg/m³Lincoln, 30 August: 20.2 µg/m³Lincoln, 31 August: 11.0 µg/m³Lincoln, 1 September: 7.1 µg/m³Lincoln, 2 September: 10.8 µg/m³Lincoln, 3 September: 8.8 µg/m³Lincoln, 4 September: 10.0 µg/m³Lincoln, 5 September: 14.3 µg/m³Lincoln, 6 September: 70.1 µg/m³, 10× its usual 6.7Lincoln, 7 September: 49.9 µg/m³, 7.2× its usual 6.9Lincoln, 8 September: 19.0 µg/m³Lincoln, 9 September: no readingLincoln, 10 September: no readingLincoln, 11 September: no readingVermillionVermillion, 25 August: 6.4 µg/m³Vermillion, 26 August: 6.4 µg/m³Vermillion, 27 August: 4.7 µg/m³Vermillion, 28 August: 8.7 µg/m³Vermillion, 29 August: 24.3 µg/m³Vermillion, 30 August: 33.2 µg/m³Vermillion, 31 August: 14.8 µg/m³Vermillion, 1 September: 9.8 µg/m³Vermillion, 2 September: 10.4 µg/m³Vermillion, 3 September: 9.1 µg/m³Vermillion, 4 September: 11.4 µg/m³Vermillion, 5 September: 23.3 µg/m³Vermillion, 6 September: 68.6 µg/m³, 14× its usual 4.6Vermillion, 7 September: 49.5 µg/m³, 9.9× its usual 4.6Vermillion, 8 September: 43.2 µg/m³, 8.6× its usual 4.7Vermillion, 9 September: 43.8 µg/m³Vermillion, 10 September: 41.4 µg/m³Vermillion, 11 September: 21.8 µg/m³WichitaWichita, 25 August: 16.9 µg/m³Wichita, 26 August: 5.9 µg/m³Wichita, 27 August: 12.3 µg/m³Wichita, 28 August: 12.1 µg/m³Wichita, 29 August: 17.2 µg/m³Wichita, 30 August: 26.2 µg/m³Wichita, 31 August: 16.1 µg/m³Wichita, 1 September: 18.4 µg/m³Wichita, 2 September: 16.0 µg/m³Wichita, 3 September: 16.6 µg/m³Wichita, 4 September: 15.3 µg/m³Wichita, 5 September: 13.3 µg/m³Wichita, 6 September: 61.9 µg/m³, 6.2× its usual 10.0Wichita, 7 September: 48.2 µg/m³, 4.7× its usual 10.3Wichita, 8 September: 33.1 µg/m³, 3.2× its usual 10.3Wichita, 9 September: 15.5 µg/m³Wichita, 10 September: 14.6 µg/m³Wichita, 11 September: 10.4 µg/m³ChanuteChanute, 25 August: 18.8 µg/m³Chanute, 26 August: 7.8 µg/m³Chanute, 27 August: 12.5 µg/m³Chanute, 28 August: 10.8 µg/m³Chanute, 29 August: 15.7 µg/m³Chanute, 30 August: 21.5 µg/m³Chanute, 31 August: 13.7 µg/m³Chanute, 1 September: 11.9 µg/m³Chanute, 2 September: 10.7 µg/m³Chanute, 3 September: 16.8 µg/m³Chanute, 4 September: 16.0 µg/m³Chanute, 5 September: 11.4 µg/m³Chanute, 6 September: 45.5 µg/m³, 5.3× its usual 8.6Chanute, 7 September: 61.4 µg/m³, 6.9× its usual 8.9Chanute, 8 September: 29.9 µg/m³, 3.3× its usual 9.0Chanute, 9 September: 14.0 µg/m³Chanute, 10 September: 11.6 µg/m³Chanute, 11 September: 13.1 µg/m³BlairBlair, 25 August: 9.3 µg/m³Blair, 26 August: 8.5 µg/m³Blair, 27 August: 4.7 µg/m³Blair, 28 August: 7.8 µg/m³Blair, 29 August: 17.7 µg/m³Blair, 30 August: 24.0 µg/m³Blair, 31 August: 13.2 µg/m³Blair, 1 September: 7.7 µg/m³Blair, 2 September: 11.1 µg/m³Blair, 3 September: 10.2 µg/m³Blair, 4 September: 11.2 µg/m³Blair, 5 September: 13.1 µg/m³Blair, 6 September: 59.3 µg/m³, 9.6× its usual 6.2Blair, 7 September: 38.5 µg/m³, 6.4× its usual 6.0Blair, 8 September: 22.1 µg/m³Blair, 9 September: 17.7 µg/m³Blair, 10 September: 10.9 µg/m³Blair, 11 September: 8.3 µg/m³OmahaOmaha, 25 August: 9.7 µg/m³Omaha, 26 August: 7.4 µg/m³Omaha, 27 August: 6.0 µg/m³Omaha, 28 August: 6.9 µg/m³Omaha, 29 August: 17.1 µg/m³Omaha, 30 August: 21.4 µg/m³Omaha, 31 August: 11.5 µg/m³Omaha, 1 September: 7.3 µg/m³Omaha, 2 September: 9.5 µg/m³Omaha, 3 September: 9.3 µg/m³Omaha, 4 September: 10.5 µg/m³Omaha, 5 September: 11.5 µg/m³Omaha, 6 September: 58.0 µg/m³, 8.1× its usual 7.2Omaha, 7 September: 40.1 µg/m³, 5.5× its usual 7.3Omaha, 8 September: 22.0 µg/m³Omaha, 9 September: 16.5 µg/m³Omaha, 10 September: 11.0 µg/m³Omaha, 11 September: 10.9 µg/m³Kansas CityKansas City, 25 August: 15.2 µg/m³Kansas City, 26 August: 8.4 µg/m³Kansas City, 27 August: 10.2 µg/m³Kansas City, 28 August: 10.4 µg/m³Kansas City, 29 August: 17.5 µg/m³Kansas City, 30 August: 19.5 µg/m³Kansas City, 31 August: 10.2 µg/m³Kansas City, 1 September: 6.4 µg/m³Kansas City, 2 September: 8.5 µg/m³Kansas City, 3 September: 12.9 µg/m³Kansas City, 4 September: 12.4 µg/m³Kansas City, 5 September: 10.7 µg/m³Kansas City, 6 September: 44.5 µg/m³, 5.3× its usual 8.4Kansas City, 7 September: 57.5 µg/m³, 6.9× its usual 8.3Kansas City, 8 September: 26.5 µg/m³, 3.2× its usual 8.4Kansas City, 9 September: 14.9 µg/m³Kansas City, 10 September: 11.1 µg/m³Kansas City, 11 September: 9.0 µg/m³BellevueBellevue, 25 August: 7.4 µg/m³Bellevue, 26 August: 5.9 µg/m³Bellevue, 27 August: 5.3 µg/m³Bellevue, 28 August: 5.5 µg/m³Bellevue, 29 August: 13.0 µg/m³Bellevue, 30 August: 18.7 µg/m³Bellevue, 31 August: 10.3 µg/m³Bellevue, 1 September: 5.3 µg/m³Bellevue, 2 September: 8.1 µg/m³Bellevue, 3 September: 8.3 µg/m³Bellevue, 4 September: 11.2 µg/m³Bellevue, 5 September: 10.6 µg/m³Bellevue, 6 September: 56.4 µg/m³, 9.4× its usual 6.0Bellevue, 7 September: 39.9 µg/m³, 6.6× its usual 6.0Bellevue, 8 September: 21.6 µg/m³Bellevue, 9 September: 12.8 µg/m³Bellevue, 10 September: 8.2 µg/m³Bellevue, 11 September: 8.0 µg/m³DerbyDerby, 25 August: 19.5 µg/m³Derby, 26 August: 6.7 µg/m³Derby, 27 August: 12.4 µg/m³Derby, 28 August: 12.5 µg/m³Derby, 29 August: 16.4 µg/m³Derby, 30 August: 25.9 µg/m³Derby, 31 August: 18.2 µg/m³Derby, 1 September: 17.3 µg/m³Derby, 2 September: 15.7 µg/m³Derby, 3 September: 17.0 µg/m³Derby, 4 September: 15.4 µg/m³Derby, 5 September: 12.7 µg/m³Derby, 6 September: 56.2 µg/m³, 6.5× its usual 8.6Derby, 7 September: 44.5 µg/m³, 4.9× its usual 9.1Derby, 8 September: 32.0 µg/m³, 3.5× its usual 9.1Derby, 9 September: 15.1 µg/m³Derby, 10 September: 14.6 µg/m³Derby, 11 September: 11.1 µg/m³HaysvilleHaysville, 25 August: 19.5 µg/m³Haysville, 26 August: 6.7 µg/m³Haysville, 27 August: 12.4 µg/m³Haysville, 28 August: 12.5 µg/m³Haysville, 29 August: 16.4 µg/m³Haysville, 30 August: 25.9 µg/m³Haysville, 31 August: 18.2 µg/m³Haysville, 1 September: 17.3 µg/m³Haysville, 2 September: 15.7 µg/m³Haysville, 3 September: 17.0 µg/m³Haysville, 4 September: 15.4 µg/m³Haysville, 5 September: 12.7 µg/m³Haysville, 6 September: 56.2 µg/m³, 6.5× its usual 8.6Haysville, 7 September: 44.5 µg/m³, 4.9× its usual 9.1Haysville, 8 September: 32.0 µg/m³, 3.5× its usual 9.1Haysville, 9 September: 15.1 µg/m³Haysville, 10 September: 14.6 µg/m³Haysville, 11 September: 11.1 µg/m³OlatheOlathe, 25 August: 19.1 µg/m³Olathe, 26 August: 8.6 µg/m³Olathe, 27 August: 11.5 µg/m³Olathe, 28 August: 10.2 µg/m³Olathe, 29 August: 16.2 µg/m³Olathe, 30 August: 20.6 µg/m³Olathe, 31 August: 10.1 µg/m³Olathe, 1 September: 6.0 µg/m³Olathe, 2 September: 8.3 µg/m³Olathe, 3 September: 13.6 µg/m³Olathe, 4 September: 12.7 µg/m³Olathe, 5 September: 10.2 µg/m³Olathe, 6 September: 42.1 µg/m³, 5.3× its usual 8.0Olathe, 7 September: 56.0 µg/m³, 6.7× its usual 8.3Olathe, 8 September: 26.0 µg/m³, 3.1× its usual 8.3Olathe, 9 September: 13.5 µg/m³Olathe, 10 September: 10.3 µg/m³Olathe, 11 September: 9.8 µg/m³Sioux FallsSioux Falls, 25 August: 2.6 µg/m³Sioux Falls, 26 August: 3.8 µg/m³Sioux Falls, 27 August: 2.7 µg/m³Sioux Falls, 28 August: 5.6 µg/m³Sioux Falls, 29 August: 21.8 µg/m³Sioux Falls, 30 August: 30.8 µg/m³Sioux Falls, 31 August: 15.2 µg/m³Sioux Falls, 1 September: 8.0 µg/m³Sioux Falls, 2 September: 7.3 µg/m³Sioux Falls, 3 September: 8.0 µg/m³Sioux Falls, 4 September: 7.3 µg/m³Sioux Falls, 5 September: 9.0 µg/m³Sioux Falls, 6 September: 52.3 µg/m³, 9.0× its usual 5.8Sioux Falls, 7 September: 30.6 µg/m³, 5.3× its usual 5.8Sioux Falls, 8 September: 22.9 µg/m³Sioux Falls, 9 September: 20.6 µg/m³Sioux Falls, 10 September: 8.5 µg/m³Sioux Falls, 11 September: 8.9 µg/m³Detroit LakesDetroit Lakes, 25 August: 9.1 µg/m³Detroit Lakes, 26 August: 5.8 µg/m³Detroit Lakes, 27 August: 8.0 µg/m³Detroit Lakes, 28 August: 15.0 µg/m³Detroit Lakes, 29 August: 37.5 µg/m³Detroit Lakes, 30 August: 25.4 µg/m³Detroit Lakes, 31 August: 21.2 µg/m³Detroit Lakes, 1 September: 14.5 µg/m³Detroit Lakes, 2 September: 16.1 µg/m³Detroit Lakes, 3 September: 17.6 µg/m³Detroit Lakes, 4 September: 14.6 µg/m³Detroit Lakes, 5 September: 21.0 µg/m³Detroit Lakes, 6 September: 52.0 µg/m³, 8.1× its usual 6.4Detroit Lakes, 7 September: 20.3 µg/m³Detroit Lakes, 8 September: 18.8 µg/m³Detroit Lakes, 9 September: 20.9 µg/m³Detroit Lakes, 10 September: 18.4 µg/m³Detroit Lakes, 11 September: 12.2 µg/m³BrookingsBrookings, 25 August: 6.0 µg/m³Brookings, 26 August: 5.2 µg/m³Brookings, 27 August: 4.8 µg/m³Brookings, 28 August: 11.3 µg/m³Brookings, 29 August: 27.0 µg/m³Brookings, 30 August: 28.1 µg/m³Brookings, 31 August: 19.0 µg/m³Brookings, 1 September: 14.6 µg/m³Brookings, 2 September: 12.8 µg/m³Brookings, 3 September: 9.1 µg/m³Brookings, 4 September: 11.2 µg/m³Brookings, 5 September: 15.1 µg/m³Brookings, 6 September: 51.6 µg/m³, 8.6× its usual 6.0Brookings, 7 September: 25.5 µg/m³, 4.2× its usual 6.1Brookings, 8 September: 24.1 µg/m³Brookings, 9 September: 18.5 µg/m³Brookings, 10 September: 11.5 µg/m³Brookings, 11 September: 10.8 µg/m³WatertownWatertown, 25 August: 9.5 µg/m³Watertown, 26 August: 6.2 µg/m³Watertown, 27 August: 7.2 µg/m³Watertown, 28 August: 12.2 µg/m³Watertown, 29 August: 32.7 µg/m³Watertown, 30 August: 29.9 µg/m³Watertown, 31 August: 21.9 µg/m³Watertown, 1 September: 15.9 µg/m³Watertown, 2 September: 16.0 µg/m³Watertown, 3 September: 12.3 µg/m³Watertown, 4 September: 11.3 µg/m³Watertown, 5 September: 20.9 µg/m³Watertown, 6 September: 50.3 µg/m³, 7.5× its usual 6.7Watertown, 7 September: 24.3 µg/m³Watertown, 8 September: 28.0 µg/m³, 4.1× its usual 6.9Watertown, 9 September: 18.2 µg/m³Watertown, 10 September: 13.4 µg/m³Watertown, 11 September: 9.8 µg/m³KearneyKearney, 25 August: 23.5 µg/m³Kearney, 26 August: 14.0 µg/m³Kearney, 27 August: 17.2 µg/m³Kearney, 28 August: 22.1 µg/m³Kearney, 29 August: 28.3 µg/m³Kearney, 30 August: 27.4 µg/m³Kearney, 31 August: 11.5 µg/m³Kearney, 1 September: 7.2 µg/m³Kearney, 2 September: 9.7 µg/m³Kearney, 3 September: 15.0 µg/m³Kearney, 4 September: 13.2 µg/m³Kearney, 5 September: 12.9 µg/m³Kearney, 6 September: 38.9 µg/m³, 6.9× its usual 5.6Kearney, 7 September: 45.9 µg/m³, 8.1× its usual 5.7Kearney, 8 September: 25.5 µg/m³, 4.5× its usual 5.7Kearney, 9 September: 17.6 µg/m³Kearney, 10 September: 16.7 µg/m³Kearney, 11 September: 14.2 µg/m³LibertyLiberty, 25 August: 23.5 µg/m³Liberty, 26 August: 14.0 µg/m³Liberty, 27 August: 17.2 µg/m³Liberty, 28 August: 22.1 µg/m³Liberty, 29 August: 28.3 µg/m³Liberty, 30 August: 27.4 µg/m³Liberty, 31 August: 11.5 µg/m³Liberty, 1 September: 7.2 µg/m³Liberty, 2 September: 9.7 µg/m³Liberty, 3 September: 15.0 µg/m³Liberty, 4 September: 13.2 µg/m³Liberty, 5 September: 12.9 µg/m³Liberty, 6 September: 38.9 µg/m³, 6.9× its usual 5.6Liberty, 7 September: 45.9 µg/m³, 8.1× its usual 5.7Liberty, 8 September: 25.5 µg/m³, 4.5× its usual 5.7Liberty, 9 September: 17.6 µg/m³Liberty, 10 September: 16.7 µg/m³Liberty, 11 September: 14.2 µg/m³Saint JosephSaint Joseph, 25 August: 13.8 µg/m³Saint Joseph, 26 August: 8.4 µg/m³Saint Joseph, 27 August: 8.1 µg/m³Saint Joseph, 28 August: 11.1 µg/m³Saint Joseph, 29 August: 13.1 µg/m³Saint Joseph, 30 August: 16.0 µg/m³Saint Joseph, 31 August: 9.3 µg/m³Saint Joseph, 1 September: 6.7 µg/m³Saint Joseph, 2 September: 8.3 µg/m³Saint Joseph, 3 September: 11.5 µg/m³Saint Joseph, 4 September: 11.9 µg/m³Saint Joseph, 5 September: 10.1 µg/m³Saint Joseph, 6 September: 39.7 µg/m³, 4.5× its usual 8.8Saint Joseph, 7 September: 43.8 µg/m³, 4.9× its usual 8.9Saint Joseph, 8 September: 22.7 µg/m³Saint Joseph, 9 September: 15.7 µg/m³Saint Joseph, 10 September: 10.3 µg/m³Saint Joseph, 11 September: 8.2 µg/m³25 Aug2729311 Sep246810
The 60 cities with the highest readings of 82, 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
Prince AlbertSaskatchewan, Canada7 354.03 September10.833×
Grand CentreAlberta, Canada8 292.03 September9.132×
SaskatoonSaskatchewan, Canada7 270.03 September9.728×
HavreMontana, United States3 136.04 September4.927×
Swift CurrentSaskatchewan, Canada7 205.04 September7.627×
Fort St. JohnBritish Columbia, Canada7 155.02 September6.125×
Fort McMurrayAlberta, Canada8 306.52 September12.924×
QuesnelBritish Columbia, Canada7 219.03 September9.224×
Grande PrairieAlberta, Canada8 160.03 September8.120×
ReginaSaskatchewan, Canada8 176.04 September9.020×
Fort SaskatchewanAlberta, Canada9 178.03 September9.619×
EdmontonAlberta, Canada9 201.03 September11.318×
SheridanWyoming, United States2 91.55 September5.218×
GilletteWyoming, United States2 90.45 September5.217×
BillingsMontana, United States2 115.05 September6.917×
LockwoodMontana, United States2 115.05 September6.917×
Flin FlonManitoba, Canada4 217.03 September13.816×
Medicine HatAlberta, Canada3 109.04 September7.315×
Miles CityMontana, United States2 111.05 September7.714×
Sherwood ParkAlberta, Canada7 114.03 September8.014×
LewistownMontana, United States2 93.25 September6.614×
VermillionSouth Dakota, United States3 68.66 September4.614×
CalgaryAlberta, Canada5 143.04 September11.213×
St. AlbertAlberta, Canada7 104.03 September8.113×
Williams LakeBritish Columbia, Canada2 63.93 September4.813×
AirdrieAlberta, Canada4 93.74 September7.612×
Red DeerAlberta, Canada9 111.73 September9.712×
Grand IslandNebraska, United States3 71.06 September6.411×
MarshallMinnesota, United States3 70.46 September6.711×
LincolnNebraska, United States2 70.16 September6.711×
Rapid CitySouth Dakota, United States1 73.65 September7.110×
BeatriceNebraska, United States3 72.26 September7.110×
EdsonAlberta, Canada6 70.73 September7.010×
LethbridgeAlberta, Canada3 83.94 September8.69.8×
BlairNebraska, United States2 59.36 September6.29.6×
PierreSouth Dakota, United States2 49.05 September5.19.6×
BellevueNebraska, United States2 56.46 September6.09.4×
CodyWyoming, United States1 45.85 September3.79.2×
Sioux FallsSouth Dakota, United States2 52.36 September5.89.0×
Drayton ValleyAlberta, Canada6 72.43 September8.18.9×
BrookingsSouth Dakota, United States2 51.66 September6.08.6×
KamloopsBritish Columbia, Canada4 83.329 August9.88.5×
EstevanSaskatchewan, Canada7 88.43 September10.68.3×
TopekaKansas, United States3 72.47 September8.88.2×
OmahaNebraska, United States2 58.06 September7.28.1×
Detroit LakesMinnesota, United States1 52.06 September6.48.1×
KearneyMissouri, United States3 45.97 September5.78.1×
LibertyMissouri, United States3 45.97 September5.78.1×
AberdeenSouth Dakota, United States4 40.85 September5.27.8×
West FargoNorth Dakota, United States3 51.75 September6.97.5×
WatertownSouth Dakota, United States2 50.36 September6.77.5×
HopeBritish Columbia, Canada1 44.428 August6.07.4×
RaymoreMissouri, United States2 41.37 September5.87.1×
ChanuteKansas, United States3 61.47 September8.96.9×
Kansas CityKansas, United States3 57.57 September8.36.9×
Great FallsMontana, United States2 78.14 September11.76.7×
OlatheKansas, United States3 56.07 September8.36.7×
DerbyKansas, United States3 56.26 September8.66.5×
HaysvilleKansas, United States3 56.26 September8.66.5×
Prince GeorgeBritish Columbia, Canada5 64.04 September10.06.4×
Kansas CityMissouri, United States2 43.57 September6.96.3×
WichitaKansas, United States3 61.96 September10.06.2×
ScottsbluffNebraska, United States1 30.85 September4.36.2×
PentictonBritish Columbia, Canada2 39.028 August6.56.0×
CasperWyoming, United States1 26.85 September3.45.4×
Ponca CityOklahoma, United States3 43.46 September8.65.0×
Saint JosephMissouri, United States2 43.87 September8.94.9×
AnkenyIowa, United States1 35.56 September7.44.8×
Des MoinesIowa, United States1 34.76 September7.44.7×
EphrataWashington, United States1 32.929 August7.04.7×
HelenaMontana, United States2 35.15 September7.94.4×
Helena Valley West CentralMontana, United States2 35.15 September7.94.4×
GlenpoolOklahoma, United States2 35.47 September8.64.1×
JenksOklahoma, United States2 35.47 September8.64.1×
AgassizBritish Columbia, Canada1 26.328 August6.44.1×
ChilliwackBritish Columbia, Canada1 25.328 August6.34.0×
VernonBritish Columbia, Canada3 32.329 August8.63.8×
Iowa CityIowa, United States1 27.56 September7.33.8×
Saint CloudMinnesota, United States1 26.66 September7.03.8×
KelownaBritish Columbia, Canada2 31.128 August8.43.7×
TulsaOklahoma, United States1 34.87 September9.83.6×
MiamiOklahoma, United States1 34.46 September11.43.0×

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 the United States and Canada

Number 19 of 173 episodes in the United States and Canada since our records began, by cities reached.

Bars: cities reached; colour: the level of the episode's highest daily reading. All 173.

Use this page

SmogRank, Northern United States and Canada, August and September 2023: 82 cities with PM2.5 at twice their usual or more, 28 August to 8 September 2023, smogrank.com/episodes/2023-08-northern-united-states-and-canada (accessed 5 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. Fire detections from NASA FIRMS; smoke maps from NOAA HMS.