SmogRank / Episodes / United States

North-western United States and Canada, August and September 2025

For 8 days, from 31 August to 7 September 2025, 94 cities in the United States and Canada had PM2.5 at least twice their usual for the time of year. The worst reading was Squamish, British Columbia, Canada: 173.0 µg/m³ on 3 September, about 25× its usual 7.0. Ended 7 September.

Likely smoke from firesFires were detected within 300 km of the city on 33% 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 reached94in 2 countries
Days831 August to 7 September 2025
Worst day5 September55 cities counted
Furthest above usual25×Squamish

Day by day

5 September 55 cities at twice their usual or more
ButteLa GrandePendletonTwin FallsBurleyPocatelloNorth BendThe DallesMount VernonBellevueHood RiverPicnic Point-North LynnwoodRentonLyndenAuburnCondaBellinghamSeattleWhite CenterBurienAnacortesLangleyMadrasOak HarborTacomaParklandCodyBremertonPort TownsendPrestonRedmondDeltaLaceyRichmondSmithfieldBendGreshamCentraliaSheltonChehalisBrigham CityVictoriaSalmon CreekVancouverRidgefieldPort AngelesNorth PortlandLongviewPortlandMilwaukieLangfordOregon CityNorth OgdenTigardBeavertonCanbyNorth CowichanDuncanHillsboroWoodburnSilvertonWorlandForest GroveNanaimoHarewoodStaytonBountifulLanderAberdeenMagnaStansbury parkSalemSalt Lake CitySweet HomeMcMinnvilleWest Valley CityMillcreekRivertonTooeleWest JordanAlbanySheridanDallasCorvallisEugeneRock SpringsCottage GroveMiles CityAltamontPort AlberniCampbell RiverRoseburgGreenGilletteCasperCoos BayReddingBrookingsCrescent CityLaramieRapid CityRanchettesCheyenneFort CollinsScottsbluffFlin FlonKitimatTerraceEstevanGreat FallsWeiserSunnysideReginaPrince AlbertKamloopsHelena Valley West CentralHelenaCranbrookColumbia FallsQuesnelMoses LakeBaker CityLewistonRexburgNampaLewistownBozemanCrestonWalla WallaLockwoodBillingsChilliwackMoscowMeridianSandpointAbbotsfordMissoulaVernonSaskatoonHavreHermistonProsserAirdrieOntarioAirway HeightsCoeur d'AleneKelownaPullmanBoiseSpokaneCastlegarAgassizIdaho FallsMedfordShorelineGrand CentrePort CoquitlamGlendiveSpokane ValleyRed DeerMissionVancouverStrawberry HillToppenishSwift CurrentQuincyMedicine HatPrince GeorgeTalentNorth VancouverMeadBurnabyFort McMurrayTri-CitiesWilliams LakeDrayton ValleySmithersCoquitlamInglewood-Finn HillEllensburgGibsonsKirklandAshlandEphrataLethbridgeYakimaGrants PassCalgaryEdsonPrinevilleWenatcheeYrekaWhistlerHopeEdmontonFort SaskatchewanSt. AlbertSherwood ParkWest VancouverGrande PrairieFort St. JohnSquamish
28 Aug2930311 Sep2345678910
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

EdmontonEdmonton, 28 August: 20.3 µg/m³Edmonton, 29 August: 27.1 µg/m³Edmonton, 30 August: 18.4 µg/m³Edmonton, 31 August: 76.6 µg/m³, 6.7× its usual 11.5Edmonton, 1 September: 140.0 µg/m³, 12× its usual 11.4Edmonton, 2 September: 46.6 µg/m³, 4.1× its usual 11.4Edmonton, 3 September: 48.2 µg/m³, 4.3× its usual 11.3Edmonton, 4 September: 36.8 µg/m³, 3.3× its usual 11.3Edmonton, 5 September: 14.3 µg/m³Edmonton, 6 September: 22.4 µg/m³Edmonton, 7 September: 36.8 µg/m³Edmonton, 8 September: 39.1 µg/m³Edmonton, 9 September: 45.1 µg/m³Edmonton, 10 September: 35.3 µg/m³Fort SaskatchewanFort Saskatchewan, 28 August: 15.8 µg/m³Fort Saskatchewan, 29 August: 17.7 µg/m³Fort Saskatchewan, 30 August: 13.9 µg/m³Fort Saskatchewan, 31 August: 76.1 µg/m³, 7.9× its usual 9.6Fort Saskatchewan, 1 September: 135.0 µg/m³, 14× its usual 9.5Fort Saskatchewan, 2 September: 44.4 µg/m³, 4.6× its usual 9.6Fort Saskatchewan, 3 September: 44.3 µg/m³, 4.7× its usual 9.5Fort Saskatchewan, 4 September: 34.8 µg/m³, 3.6× its usual 9.6Fort Saskatchewan, 5 September: 13.2 µg/m³Fort Saskatchewan, 6 September: 20.0 µg/m³Fort Saskatchewan, 7 September: 31.7 µg/m³Fort Saskatchewan, 8 September: 29.6 µg/m³Fort Saskatchewan, 9 September: 36.1 µg/m³Fort Saskatchewan, 10 September: 31.1 µg/m³Sherwood ParkSherwood Park, 28 August: 13.0 µg/m³Sherwood Park, 29 August: 19.2 µg/m³Sherwood Park, 30 August: 10.1 µg/m³Sherwood Park, 31 August: 58.0 µg/m³, 7.0× its usual 8.3Sherwood Park, 1 September: 126.0 µg/m³, 16× its usual 8.0Sherwood Park, 2 September: 41.9 µg/m³, 5.2× its usual 8.0Sherwood Park, 3 September: 42.7 µg/m³, 5.4× its usual 7.9Sherwood Park, 4 September: 32.7 µg/m³, 4.1× its usual 8.0Sherwood Park, 5 September: 10.3 µg/m³Sherwood Park, 6 September: 16.4 µg/m³Sherwood Park, 7 September: 26.1 µg/m³Sherwood Park, 8 September: 27.2 µg/m³Sherwood Park, 9 September: 34.6 µg/m³Sherwood Park, 10 September: 28.8 µg/m³St. AlbertSt. Albert, 28 August: 16.2 µg/m³St. Albert, 29 August: 21.5 µg/m³St. Albert, 30 August: 16.0 µg/m³St. Albert, 31 August: 52.9 µg/m³, 6.4× its usual 8.3St. Albert, 1 September: 126.0 µg/m³, 15× its usual 8.2St. Albert, 2 September: 42.4 µg/m³, 5.2× its usual 8.2St. Albert, 3 September: 44.2 µg/m³, 5.5× its usual 8.1St. Albert, 4 September: 33.6 µg/m³, 4.1× its usual 8.2St. Albert, 5 September: 15.4 µg/m³St. Albert, 6 September: 21.3 µg/m³St. Albert, 7 September: 27.7 µg/m³St. Albert, 8 September: 27.6 µg/m³St. Albert, 9 September: 36.4 µg/m³St. Albert, 10 September: 24.9 µg/m³Fort McMurrayFort McMurray, 28 August: 16.0 µg/m³Fort McMurray, 29 August: 70.6 µg/m³Fort McMurray, 30 August: 41.5 µg/m³Fort McMurray, 31 August: 96.3 µg/m³, 6.9× its usual 13.9Fort McMurray, 1 September: 59.3 µg/m³, 4.4× its usual 13.6Fort McMurray, 2 September: 48.9 µg/m³, 3.7× its usual 13.2Fort McMurray, 3 September: 55.5 µg/m³, 4.3× its usual 12.9Fort McMurray, 4 September: 11.5 µg/m³Fort McMurray, 5 September: 6.8 µg/m³Fort McMurray, 6 September: 32.7 µg/m³Fort McMurray, 7 September: 21.1 µg/m³Fort McMurray, 8 September: 27.1 µg/m³Fort McMurray, 9 September: 34.8 µg/m³Fort McMurray, 10 September: 17.7 µg/m³Grand CentreGrand Centre, 28 August: 10.9 µg/m³Grand Centre, 29 August: 17.5 µg/m³Grand Centre, 30 August: 12.8 µg/m³Grand Centre, 31 August: 30.1 µg/m³, 3.1× its usual 9.6Grand Centre, 1 September: 55.9 µg/m³, 5.9× its usual 9.5Grand Centre, 2 September: 56.5 µg/m³, 6.0× its usual 9.4Grand Centre, 3 September: 33.1 µg/m³, 3.5× its usual 9.4Grand Centre, 4 September: 17.6 µg/m³Grand Centre, 5 September: 8.0 µg/m³Grand Centre, 6 September: 5.8 µg/m³Grand Centre, 7 September: 12.3 µg/m³Grand Centre, 8 September: 22.6 µg/m³Grand Centre, 9 September: 24.9 µg/m³Grand Centre, 10 September: 26.1 µg/m³Grande PrairieGrande Prairie, 28 August: 19.5 µg/m³Grande Prairie, 29 August: 17.9 µg/m³Grande Prairie, 30 August: 15.0 µg/m³Grande Prairie, 31 August: 152.0 µg/m³Grande Prairie, 1 September: 166.0 µg/m³, 20× its usual 8.2Grande Prairie, 2 September: 68.6 µg/m³, 8.4× its usual 8.2Grande Prairie, 3 September: 47.0 µg/m³, 5.8× its usual 8.1Grande Prairie, 4 September: 36.2 µg/m³, 4.6× its usual 7.8Grande Prairie, 5 September: 23.5 µg/m³Grande Prairie, 6 September: 28.9 µg/m³Grande Prairie, 7 September: 36.8 µg/m³Grande Prairie, 8 September: 36.2 µg/m³Grande Prairie, 9 September: 35.9 µg/m³Grande Prairie, 10 September: 11.2 µg/m³Fort St. JohnFort St. John, 28 August: 6.2 µg/m³Fort St. John, 29 August: 7.8 µg/m³Fort St. John, 30 August: 6.4 µg/m³Fort St. John, 31 August: 96.2 µg/m³Fort St. John, 1 September: 140.0 µg/m³, 23× its usual 6.2Fort St. John, 2 September: 49.7 µg/m³, 8.1× its usual 6.1Fort St. John, 3 September: 39.8 µg/m³, 6.5× its usual 6.1Fort St. John, 4 September: 15.2 µg/m³Fort St. John, 5 September: 12.4 µg/m³Fort St. John, 6 September: 20.8 µg/m³Fort St. John, 7 September: 37.5 µg/m³Fort St. John, 8 September: 26.8 µg/m³Fort St. John, 9 September: 13.1 µg/m³Fort St. John, 10 September: 5.7 µg/m³EdsonEdson, 28 August: 19.2 µg/m³Edson, 29 August: 23.1 µg/m³Edson, 30 August: 16.5 µg/m³Edson, 31 August: 16.4 µg/m³Edson, 1 September: 63.2 µg/m³, 9.0× its usual 7.0Edson, 2 September: 71.1 µg/m³, 10× its usual 7.0Edson, 3 September: 37.2 µg/m³, 5.3× its usual 7.0Edson, 4 September: 35.9 µg/m³, 5.1× its usual 7.0Edson, 5 September: 18.2 µg/m³Edson, 6 September: 19.4 µg/m³Edson, 7 September: 18.6 µg/m³Edson, 8 September: 29.0 µg/m³Edson, 9 September: 31.3 µg/m³Edson, 10 September: 21.3 µg/m³Prince GeorgePrince George, 28 August: 19.8 µg/m³Prince George, 29 August: 19.4 µg/m³Prince George, 30 August: 19.4 µg/m³Prince George, 31 August: 22.5 µg/m³Prince George, 1 September: 27.1 µg/m³, 2.7× its usual 10.0Prince George, 2 September: 62.3 µg/m³, 6.3× its usual 9.9Prince George, 3 September: 41.9 µg/m³, 4.2× its usual 9.9Prince George, 4 September: 33.5 µg/m³, 3.4× its usual 9.8Prince George, 5 September: 64.2 µg/m³, 6.7× its usual 9.6Prince George, 6 September: 31.4 µg/m³Prince George, 7 September: 49.8 µg/m³Prince George, 8 September: 49.7 µg/m³Prince George, 9 September: 29.0 µg/m³Prince George, 10 September: 18.3 µg/m³Red DeerRed Deer, 28 August: 12.5 µg/m³Red Deer, 29 August: 14.0 µg/m³Red Deer, 30 August: 10.9 µg/m³Red Deer, 31 August: 10.7 µg/m³Red Deer, 1 September: 54.1 µg/m³, 5.7× its usual 9.5Red Deer, 2 September: 58.6 µg/m³, 6.2× its usual 9.4Red Deer, 3 September: 46.8 µg/m³, 5.0× its usual 9.4Red Deer, 4 September: 35.7 µg/m³, 3.8× its usual 9.5Red Deer, 5 September: 23.7 µg/m³Red Deer, 6 September: 21.7 µg/m³Red Deer, 7 September: 24.4 µg/m³Red Deer, 8 September: 28.4 µg/m³Red Deer, 9 September: 30.5 µg/m³Red Deer, 10 September: 26.5 µg/m³Drayton ValleyDrayton Valley, 28 August: 16.1 µg/m³Drayton Valley, 29 August: 20.9 µg/m³Drayton Valley, 30 August: 18.1 µg/m³Drayton Valley, 31 August: 13.6 µg/m³Drayton Valley, 1 September: 57.2 µg/m³, 7.1× its usual 8.1Drayton Valley, 2 September: 40.4 µg/m³, 5.1× its usual 8.0Drayton Valley, 3 September: 33.9 µg/m³, 4.2× its usual 8.0Drayton Valley, 4 September: 24.9 µg/m³Drayton Valley, 5 September: 17.1 µg/m³Drayton Valley, 6 September: 22.7 µg/m³Drayton Valley, 7 September: 22.4 µg/m³Drayton Valley, 8 September: 20.6 µg/m³Drayton Valley, 9 September: 34.8 µg/m³Drayton Valley, 10 September: 13.2 µg/m³SaskatoonSaskatoon, 28 August: 16.5 µg/m³Saskatoon, 29 August: 16.3 µg/m³Saskatoon, 30 August: 9.3 µg/m³Saskatoon, 31 August: 8.3 µg/m³Saskatoon, 1 September: 55.3 µg/m³, 5.1× its usual 10.9Saskatoon, 2 September: 26.0 µg/m³, 2.5× its usual 10.5Saskatoon, 3 September: no readingSaskatoon, 4 September: 14.4 µg/m³Saskatoon, 5 September: 6.0 µg/m³Saskatoon, 6 September: 9.4 µg/m³Saskatoon, 7 September: 11.0 µg/m³Saskatoon, 8 September: 29.8 µg/m³Saskatoon, 9 September: 31.6 µg/m³Saskatoon, 10 September: 22.2 µg/m³Swift CurrentSwift Current, 28 August: 14.2 µg/m³Swift Current, 29 August: 7.3 µg/m³Swift Current, 30 August: 6.0 µg/m³Swift Current, 31 August: 6.3 µg/m³Swift Current, 1 September: 37.5 µg/m³, 4.6× its usual 8.2Swift Current, 2 September: 53.4 µg/m³, 6.5× its usual 8.2Swift Current, 3 September: 19.7 µg/m³Swift Current, 4 September: 26.2 µg/m³, 3.2× its usual 8.2Swift Current, 5 September: 8.0 µg/m³Swift Current, 6 September: 5.6 µg/m³Swift Current, 7 September: 8.8 µg/m³Swift Current, 8 September: 19.3 µg/m³Swift Current, 9 September: 20.1 µg/m³Swift Current, 10 September: 16.8 µg/m³Prince AlbertPrince Albert, 28 August: 17.3 µg/m³Prince Albert, 29 August: 16.0 µg/m³Prince Albert, 30 August: 14.4 µg/m³Prince Albert, 31 August: 11.3 µg/m³Prince Albert, 1 September: 38.8 µg/m³, 3.4× its usual 11.5Prince Albert, 2 September: 18.0 µg/m³Prince Albert, 3 September: 10.8 µg/m³Prince Albert, 4 September: 11.5 µg/m³Prince Albert, 5 September: 7.8 µg/m³Prince Albert, 6 September: 10.7 µg/m³Prince Albert, 7 September: 10.4 µg/m³Prince Albert, 8 September: 24.4 µg/m³Prince Albert, 9 September: 24.2 µg/m³Prince Albert, 10 September: 24.1 µg/m³CalgaryCalgary, 28 August: 12.8 µg/m³Calgary, 29 August: 12.7 µg/m³Calgary, 30 August: 12.5 µg/m³Calgary, 31 August: 12.9 µg/m³Calgary, 1 September: 20.2 µg/m³Calgary, 2 September: 100.3 µg/m³, 9.9× its usual 10.1Calgary, 3 September: 57.2 µg/m³, 5.7× its usual 10.1Calgary, 4 September: 47.8 µg/m³, 4.6× its usual 10.3Calgary, 5 September: 37.0 µg/m³, 3.7× its usual 10.1Calgary, 6 September: 31.2 µg/m³Calgary, 7 September: 33.7 µg/m³Calgary, 8 September: 32.1 µg/m³Calgary, 9 September: 30.8 µg/m³Calgary, 10 September: 25.2 µg/m³LethbridgeLethbridge, 28 August: 9.1 µg/m³Lethbridge, 29 August: 7.9 µg/m³Lethbridge, 30 August: 8.3 µg/m³Lethbridge, 31 August: 11.4 µg/m³Lethbridge, 1 September: 20.7 µg/m³Lethbridge, 2 September: 72.8 µg/m³, 9.2× its usual 7.9Lethbridge, 3 September: 62.0 µg/m³, 7.8× its usual 7.9Lethbridge, 4 September: 40.9 µg/m³, 5.1× its usual 8.0Lethbridge, 5 September: 30.6 µg/m³, 3.9× its usual 7.9Lethbridge, 6 September: 19.8 µg/m³Lethbridge, 7 September: 39.5 µg/m³Lethbridge, 8 September: 31.1 µg/m³Lethbridge, 9 September: 18.3 µg/m³Lethbridge, 10 September: 14.8 µg/m³Medicine HatMedicine Hat, 28 August: 8.8 µg/m³Medicine Hat, 29 August: 7.0 µg/m³Medicine Hat, 30 August: 8.7 µg/m³Medicine Hat, 31 August: 9.9 µg/m³Medicine Hat, 1 September: 14.4 µg/m³Medicine Hat, 2 September: 48.0 µg/m³, 6.7× its usual 7.2Medicine Hat, 3 September: 33.8 µg/m³, 4.7× its usual 7.2Medicine Hat, 4 September: 27.5 µg/m³, 3.9× its usual 7.1Medicine Hat, 5 September: 10.4 µg/m³Medicine Hat, 6 September: 6.9 µg/m³Medicine Hat, 7 September: 16.8 µg/m³Medicine Hat, 8 September: 18.6 µg/m³Medicine Hat, 9 September: 19.8 µg/m³Medicine Hat, 10 September: 15.9 µg/m³QuesnelQuesnel, 28 August: 16.5 µg/m³Quesnel, 29 August: 15.3 µg/m³Quesnel, 30 August: 15.7 µg/m³Quesnel, 31 August: 15.8 µg/m³Quesnel, 1 September: 19.3 µg/m³Quesnel, 2 September: 35.1 µg/m³, 3.8× its usual 9.2Quesnel, 3 September: 35.7 µg/m³, 3.9× its usual 9.1Quesnel, 4 September: 30.5 µg/m³, 3.4× its usual 8.9Quesnel, 5 September: 28.7 µg/m³, 3.4× its usual 8.5Quesnel, 6 September: 25.1 µg/m³Quesnel, 7 September: 55.3 µg/m³Quesnel, 8 September: 68.2 µg/m³Quesnel, 9 September: 36.4 µg/m³Quesnel, 10 September: 43.6 µg/m³SquamishSquamish, 28 August: 14.1 µg/m³Squamish, 29 August: 15.9 µg/m³Squamish, 30 August: 13.2 µg/m³Squamish, 31 August: 20.9 µg/m³Squamish, 1 September: 12.1 µg/m³Squamish, 2 September: 17.0 µg/m³Squamish, 3 September: 173.0 µg/m³, 25× its usual 7.0Squamish, 4 September: 53.1 µg/m³, 7.6× its usual 7.0Squamish, 5 September: 43.1 µg/m³, 6.3× its usual 6.8Squamish, 6 September: 49.3 µg/m³Squamish, 7 September: 11.8 µg/m³Squamish, 8 September: 8.2 µg/m³Squamish, 9 September: 9.4 µg/m³Squamish, 10 September: 7.7 µg/m³West VancouverWest Vancouver, 28 August: 13.0 µg/m³West Vancouver, 29 August: 14.3 µg/m³West Vancouver, 30 August: 8.8 µg/m³West Vancouver, 31 August: 12.9 µg/m³West Vancouver, 1 September: 8.3 µg/m³West Vancouver, 2 September: 9.7 µg/m³West Vancouver, 3 September: 87.2 µg/m³, 17× its usual 5.2West Vancouver, 4 September: 21.8 µg/m³West Vancouver, 5 September: 31.4 µg/m³, 6.3× its usual 4.9West Vancouver, 6 September: 28.1 µg/m³West Vancouver, 7 September: 9.6 µg/m³West Vancouver, 8 September: 6.7 µg/m³West Vancouver, 9 September: 7.3 µg/m³West Vancouver, 10 September: 5.0 µg/m³HopeHope, 28 August: 14.7 µg/m³Hope, 29 August: 13.5 µg/m³Hope, 30 August: 10.1 µg/m³Hope, 31 August: 12.4 µg/m³Hope, 1 September: 10.7 µg/m³Hope, 2 September: 13.6 µg/m³Hope, 3 September: 28.0 µg/m³, 4.6× its usual 6.1Hope, 4 September: 25.7 µg/m³, 4.2× its usual 6.1Hope, 5 September: 69.1 µg/m³, 12× its usual 5.9Hope, 6 September: 43.1 µg/m³Hope, 7 September: 9.5 µg/m³Hope, 8 September: 6.8 µg/m³Hope, 9 September: 9.7 µg/m³Hope, 10 September: 34.4 µg/m³WhistlerWhistler, 28 August: 9.9 µg/m³Whistler, 29 August: 9.5 µg/m³Whistler, 30 August: 11.6 µg/m³Whistler, 31 August: 13.1 µg/m³Whistler, 1 September: 12.3 µg/m³Whistler, 2 September: 20.6 µg/m³Whistler, 3 September: 34.7 µg/m³, 6.9× its usual 4.8Whistler, 4 September: 38.4 µg/m³, 7.7× its usual 4.8Whistler, 5 September: 56.3 µg/m³, 11× its usual 4.6Whistler, 6 September: 65.5 µg/m³Whistler, 7 September: 12.5 µg/m³Whistler, 8 September: 4.6 µg/m³Whistler, 9 September: 5.8 µg/m³Whistler, 10 September: 8.7 µg/m³GibsonsGibsons, 28 August: 15.5 µg/m³Gibsons, 29 August: 16.8 µg/m³Gibsons, 30 August: 11.1 µg/m³Gibsons, 31 August: 13.9 µg/m³Gibsons, 1 September: 10.9 µg/m³Gibsons, 2 September: 16.3 µg/m³Gibsons, 3 September: 48.7 µg/m³, 7.6× its usual 6.4Gibsons, 4 September: 37.9 µg/m³, 6.0× its usual 6.3Gibsons, 5 September: 40.4 µg/m³, 6.4× its usual 6.3Gibsons, 6 September: 31.2 µg/m³Gibsons, 7 September: 10.5 µg/m³Gibsons, 8 September: 7.8 µg/m³Gibsons, 9 September: 8.5 µg/m³Gibsons, 10 September: 7.3 µg/m³ToppenishToppenish, 28 August: 15.8 µg/m³Toppenish, 29 August: 14.4 µg/m³Toppenish, 30 August: 13.7 µg/m³Toppenish, 31 August: 13.2 µg/m³Toppenish, 1 September: 22.0 µg/m³Toppenish, 2 September: 23.2 µg/m³Toppenish, 3 September: 25.1 µg/m³, 3.3× its usual 7.6Toppenish, 4 September: 45.5 µg/m³, 6.0× its usual 7.6Toppenish, 5 September: 48.2 µg/m³, 6.4× its usual 7.5Toppenish, 6 September: 44.8 µg/m³Toppenish, 7 September: 22.5 µg/m³Toppenish, 8 September: 12.1 µg/m³Toppenish, 9 September: 8.0 µg/m³Toppenish, 10 September: 15.9 µg/m³CoquitlamCoquitlam, 28 August: 12.9 µg/m³Coquitlam, 29 August: 12.8 µg/m³Coquitlam, 30 August: 8.7 µg/m³Coquitlam, 31 August: 11.0 µg/m³Coquitlam, 1 September: 8.7 µg/m³Coquitlam, 2 September: 11.9 µg/m³Coquitlam, 3 September: 40.1 µg/m³, 7.4× its usual 5.4Coquitlam, 4 September: 21.5 µg/m³Coquitlam, 5 September: 21.9 µg/m³Coquitlam, 6 September: 16.6 µg/m³Coquitlam, 7 September: 7.1 µg/m³Coquitlam, 8 September: 6.8 µg/m³Coquitlam, 9 September: 8.0 µg/m³Coquitlam, 10 September: 5.6 µg/m³SandpointSandpoint, 28 August: 18.0 µg/m³Sandpoint, 29 August: 15.7 µg/m³Sandpoint, 30 August: 14.6 µg/m³Sandpoint, 31 August: 19.0 µg/m³Sandpoint, 1 September: 16.3 µg/m³Sandpoint, 2 September: 18.9 µg/m³Sandpoint, 3 September: 27.6 µg/m³, 3.5× its usual 7.9Sandpoint, 4 September: 33.0 µg/m³, 4.2× its usual 7.9Sandpoint, 5 September: 38.8 µg/m³, 4.9× its usual 7.9Sandpoint, 6 September: 50.5 µg/m³Sandpoint, 7 September: 26.1 µg/m³Sandpoint, 8 September: 19.0 µg/m³Sandpoint, 9 September: 20.9 µg/m³Sandpoint, 10 September: 17.8 µg/m³KirklandKirkland, 28 August: 15.0 µg/m³Kirkland, 29 August: 18.0 µg/m³Kirkland, 30 August: 12.5 µg/m³Kirkland, 31 August: 15.0 µg/m³Kirkland, 1 September: 12.4 µg/m³Kirkland, 2 September: 14.7 µg/m³Kirkland, 3 September: 25.4 µg/m³, 5.1× its usual 3.8Kirkland, 4 September: 20.0 µg/m³Kirkland, 5 September: 38.8 µg/m³, 7.8× its usual 3.5Kirkland, 6 September: 16.1 µg/m³Kirkland, 7 September: 4.4 µg/m³Kirkland, 8 September: 6.5 µg/m³Kirkland, 9 September: 8.2 µg/m³Kirkland, 10 September: 9.1 µg/m³SpokaneSpokane, 28 August: 11.9 µg/m³Spokane, 29 August: 11.9 µg/m³Spokane, 30 August: 15.0 µg/m³Spokane, 31 August: 18.9 µg/m³Spokane, 1 September: 15.2 µg/m³Spokane, 2 September: 19.2 µg/m³Spokane, 3 September: 30.0 µg/m³, 4.3× its usual 7.0Spokane, 4 September: 31.6 µg/m³, 4.6× its usual 6.8Spokane, 5 September: 37.7 µg/m³, 5.7× its usual 6.6Spokane, 6 September: 43.5 µg/m³Spokane, 7 September: 16.0 µg/m³Spokane, 8 September: 8.2 µg/m³Spokane, 9 September: 14.2 µg/m³Spokane, 10 September: 23.0 µg/m³BurnabyBurnaby, 28 August: 12.9 µg/m³Burnaby, 29 August: 14.4 µg/m³Burnaby, 30 August: 8.4 µg/m³Burnaby, 31 August: 10.8 µg/m³Burnaby, 1 September: 8.0 µg/m³Burnaby, 2 September: 12.1 µg/m³Burnaby, 3 September: 37.5 µg/m³, 6.9× its usual 5.4Burnaby, 4 September: 11.7 µg/m³Burnaby, 5 September: 18.1 µg/m³Burnaby, 6 September: 13.7 µg/m³Burnaby, 7 September: 7.1 µg/m³Burnaby, 8 September: 6.6 µg/m³Burnaby, 9 September: 8.3 µg/m³Burnaby, 10 September: 5.1 µg/m³Inglewood-Finn HillInglewood-Finn Hill, 28 August: 14.6 µg/m³Inglewood-Finn Hill, 29 August: 19.1 µg/m³Inglewood-Finn Hill, 30 August: 13.7 µg/m³Inglewood-Finn Hill, 31 August: 16.4 µg/m³Inglewood-Finn Hill, 1 September: 12.3 µg/m³Inglewood-Finn Hill, 2 September: 16.1 µg/m³Inglewood-Finn Hill, 3 September: 27.0 µg/m³, 5.4× its usual 4.1Inglewood-Finn Hill, 4 September: 20.9 µg/m³Inglewood-Finn Hill, 5 September: 37.5 µg/m³, 7.5× its usual 4.1Inglewood-Finn Hill, 6 September: 17.7 µg/m³Inglewood-Finn Hill, 7 September: 5.1 µg/m³Inglewood-Finn Hill, 8 September: 7.7 µg/m³Inglewood-Finn Hill, 9 September: 9.3 µg/m³Inglewood-Finn Hill, 10 September: 9.7 µg/m³MeadMead, 28 August: 13.7 µg/m³Mead, 29 August: 11.8 µg/m³Mead, 30 August: 14.7 µg/m³Mead, 31 August: 18.4 µg/m³Mead, 1 September: 14.2 µg/m³Mead, 2 September: 17.3 µg/m³Mead, 3 September: 26.0 µg/m³, 4.5× its usual 5.8Mead, 4 September: 35.5 µg/m³, 6.1× its usual 5.8Mead, 5 September: 37.3 µg/m³, 6.9× its usual 5.4Mead, 6 September: 41.0 µg/m³Mead, 7 September: 19.1 µg/m³Mead, 8 September: 9.4 µg/m³Mead, 9 September: 15.1 µg/m³Mead, 10 September: 22.1 µg/m³Spokane ValleySpokane Valley, 28 August: 12.4 µg/m³Spokane Valley, 29 August: 10.2 µg/m³Spokane Valley, 30 August: 14.6 µg/m³Spokane Valley, 31 August: 17.0 µg/m³Spokane Valley, 1 September: 14.0 µg/m³Spokane Valley, 2 September: 16.4 µg/m³Spokane Valley, 3 September: 26.6 µg/m³, 4.2× its usual 6.4Spokane Valley, 4 September: 29.5 µg/m³, 4.7× its usual 6.3Spokane Valley, 5 September: 37.2 µg/m³, 6.1× its usual 6.1Spokane Valley, 6 September: 39.0 µg/m³Spokane Valley, 7 September: 18.0 µg/m³Spokane Valley, 8 September: 7.6 µg/m³Spokane Valley, 9 September: 12.0 µg/m³Spokane Valley, 10 September: 20.8 µg/m³AgassizAgassiz, 28 August: 15.5 µg/m³Agassiz, 29 August: 14.6 µg/m³Agassiz, 30 August: 11.1 µg/m³Agassiz, 31 August: 12.7 µg/m³Agassiz, 1 September: 11.4 µg/m³Agassiz, 2 September: 13.5 µg/m³Agassiz, 3 September: 30.7 µg/m³, 4.8× its usual 6.4Agassiz, 4 September: 37.0 µg/m³, 5.8× its usual 6.4Agassiz, 5 September: 35.7 µg/m³, 5.7× its usual 6.3Agassiz, 6 September: 27.5 µg/m³Agassiz, 7 September: 8.9 µg/m³Agassiz, 8 September: 8.4 µg/m³Agassiz, 9 September: 11.2 µg/m³Agassiz, 10 September: 13.6 µg/m³SmithersSmithers, 28 August: no readingSmithers, 29 August: 6.6 µg/m³Smithers, 30 August: 7.5 µg/m³Smithers, 31 August: 6.7 µg/m³Smithers, 1 September: 11.2 µg/m³Smithers, 2 September: 22.1 µg/m³Smithers, 3 September: 25.3 µg/m³, 5.1× its usual 4.4Smithers, 4 September: 26.1 µg/m³, 5.2× its usual 4.4Smithers, 5 September: 36.6 µg/m³, 7.3× its usual 4.4Smithers, 6 September: 37.1 µg/m³Smithers, 7 September: 10.1 µg/m³Smithers, 8 September: 7.1 µg/m³Smithers, 9 September: 5.9 µg/m³Smithers, 10 September: 5.7 µg/m³Williams LakeWilliams Lake, 28 August: 4.8 µg/m³Williams Lake, 29 August: 2.8 µg/m³Williams Lake, 30 August: 1.3 µg/m³Williams Lake, 31 August: 1.3 µg/m³Williams Lake, 1 September: 2.2 µg/m³Williams Lake, 2 September: 15.3 µg/m³Williams Lake, 3 September: 34.3 µg/m³, 6.9× its usual 4.8Williams Lake, 4 September: 35.7 µg/m³, 7.1× its usual 4.7Williams Lake, 5 September: 26.3 µg/m³, 5.3× its usual 4.7Williams Lake, 6 September: 22.3 µg/m³Williams Lake, 7 September: 48.3 µg/m³Williams Lake, 8 September: 77.0 µg/m³Williams Lake, 9 September: 52.2 µg/m³Williams Lake, 10 September: 72.9 µg/m³North VancouverNorth Vancouver, 28 August: 10.8 µg/m³North Vancouver, 29 August: 11.3 µg/m³North Vancouver, 30 August: 7.1 µg/m³North Vancouver, 31 August: 10.5 µg/m³North Vancouver, 1 September: 7.8 µg/m³North Vancouver, 2 September: 8.5 µg/m³North Vancouver, 3 September: 35.1 µg/m³, 6.9× its usual 5.1North Vancouver, 4 September: 17.8 µg/m³North Vancouver, 5 September: 23.2 µg/m³North Vancouver, 6 September: 18.0 µg/m³North Vancouver, 7 September: 7.1 µg/m³North Vancouver, 8 September: 5.4 µg/m³North Vancouver, 9 September: 6.4 µg/m³North Vancouver, 10 September: 4.7 µg/m³Strawberry HillStrawberry Hill, 28 August: 10.7 µg/m³Strawberry Hill, 29 August: 11.4 µg/m³Strawberry Hill, 30 August: 7.4 µg/m³Strawberry Hill, 31 August: 10.3 µg/m³Strawberry Hill, 1 September: 7.1 µg/m³Strawberry Hill, 2 September: 10.5 µg/m³Strawberry Hill, 3 September: 34.8 µg/m³, 6.4× its usual 5.4Strawberry Hill, 4 September: 11.8 µg/m³Strawberry Hill, 5 September: 18.2 µg/m³Strawberry Hill, 6 September: 10.7 µg/m³Strawberry Hill, 7 September: 6.3 µg/m³Strawberry Hill, 8 September: 6.1 µg/m³Strawberry Hill, 9 September: 8.5 µg/m³Strawberry Hill, 10 September: 4.7 µg/m³VancouverVancouver, 28 August: 12.4 µg/m³Vancouver, 29 August: 14.5 µg/m³Vancouver, 30 August: 8.5 µg/m³Vancouver, 31 August: 11.4 µg/m³Vancouver, 1 September: 8.7 µg/m³Vancouver, 2 September: 9.6 µg/m³Vancouver, 3 September: 34.5 µg/m³, 6.4× its usual 5.4Vancouver, 4 September: 12.4 µg/m³Vancouver, 5 September: 21.5 µg/m³Vancouver, 6 September: 13.6 µg/m³Vancouver, 7 September: 7.7 µg/m³Vancouver, 8 September: 6.6 µg/m³Vancouver, 9 September: 7.4 µg/m³Vancouver, 10 September: 4.7 µg/m³WenatcheeWenatchee, 28 August: 13.2 µg/m³Wenatchee, 29 August: 11.4 µg/m³Wenatchee, 30 August: 10.6 µg/m³Wenatchee, 31 August: 10.9 µg/m³Wenatchee, 1 September: 16.8 µg/m³Wenatchee, 2 September: 21.5 µg/m³Wenatchee, 3 September: 20.3 µg/m³Wenatchee, 4 September: 36.2 µg/m³, 6.5× its usual 5.6Wenatchee, 5 September: 58.2 µg/m³, 11× its usual 5.4Wenatchee, 6 September: 83.3 µg/m³Wenatchee, 7 September: 20.4 µg/m³Wenatchee, 8 September: 22.1 µg/m³Wenatchee, 9 September: 21.6 µg/m³Wenatchee, 10 September: 17.0 µg/m³YakimaYakima, 28 August: 13.9 µg/m³Yakima, 29 August: 12.3 µg/m³Yakima, 30 August: 9.8 µg/m³Yakima, 31 August: 9.2 µg/m³Yakima, 1 September: 18.0 µg/m³Yakima, 2 September: 20.1 µg/m³Yakima, 3 September: 20.7 µg/m³Yakima, 4 September: 58.0 µg/m³, 9.4× its usual 6.2Yakima, 5 September: 44.7 µg/m³, 7.3× its usual 6.1Yakima, 6 September: 37.7 µg/m³Yakima, 7 September: 21.3 µg/m³Yakima, 8 September: 10.3 µg/m³Yakima, 9 September: 9.5 µg/m³Yakima, 10 September: 10.9 µg/m³EphrataEphrata, 28 August: 11.3 µg/m³Ephrata, 29 August: 11.3 µg/m³Ephrata, 30 August: 10.4 µg/m³Ephrata, 31 August: 12.1 µg/m³Ephrata, 1 September: 14.0 µg/m³Ephrata, 2 September: 20.5 µg/m³Ephrata, 3 September: 20.5 µg/m³Ephrata, 4 September: 27.7 µg/m³, 4.3× its usual 6.4Ephrata, 5 September: 53.9 µg/m³, 8.4× its usual 6.4Ephrata, 6 September: 103.0 µg/m³Ephrata, 7 September: 56.4 µg/m³Ephrata, 8 September: 26.4 µg/m³Ephrata, 9 September: 11.4 µg/m³Ephrata, 10 September: 15.5 µg/m³VernonVernon, 28 August: 13.0 µg/m³Vernon, 29 August: 12.8 µg/m³Vernon, 30 August: 7.0 µg/m³Vernon, 31 August: 7.3 µg/m³Vernon, 1 September: 12.7 µg/m³Vernon, 2 September: 15.0 µg/m³Vernon, 3 September: 18.8 µg/m³Vernon, 4 September: 27.5 µg/m³, 3.2× its usual 8.6Vernon, 5 September: 42.4 µg/m³, 5.1× its usual 8.3Vernon, 6 September: 38.4 µg/m³Vernon, 7 September: 33.1 µg/m³Vernon, 8 September: 11.8 µg/m³Vernon, 9 September: 11.2 µg/m³Vernon, 10 September: 12.0 µg/m³AirdrieAirdrie, 28 August: no readingAirdrie, 29 August: no readingAirdrie, 30 August: no readingAirdrie, 31 August: no readingAirdrie, 1 September: no readingAirdrie, 2 September: no readingAirdrie, 3 September: no readingAirdrie, 4 September: 41.9 µg/m³, 5.3× its usual 7.9Airdrie, 5 September: no readingAirdrie, 6 September: no readingAirdrie, 7 September: no readingAirdrie, 8 September: no readingAirdrie, 9 September: no readingAirdrie, 10 September: no readingCoeur d'AleneCoeur d'Alene, 28 August: 13.5 µg/m³Coeur d'Alene, 29 August: 10.5 µg/m³Coeur d'Alene, 30 August: 13.9 µg/m³Coeur d'Alene, 31 August: 19.0 µg/m³Coeur d'Alene, 1 September: 14.8 µg/m³Coeur d'Alene, 2 September: 15.1 µg/m³Coeur d'Alene, 3 September: 24.8 µg/m³Coeur d'Alene, 4 September: 29.8 µg/m³, 4.2× its usual 7.1Coeur d'Alene, 5 September: 37.7 µg/m³, 5.4× its usual 7.0Coeur d'Alene, 6 September: 36.8 µg/m³Coeur d'Alene, 7 September: 15.7 µg/m³Coeur d'Alene, 8 September: 10.8 µg/m³Coeur d'Alene, 9 September: 18.9 µg/m³Coeur d'Alene, 10 September: 19.3 µg/m³Airway HeightsAirway Heights, 28 August: no readingAirway Heights, 29 August: no readingAirway Heights, 30 August: no readingAirway Heights, 31 August: no readingAirway Heights, 1 September: no readingAirway Heights, 2 September: no readingAirway Heights, 3 September: no readingAirway Heights, 4 September: 25.0 µg/m³, 3.6× its usual 6.9Airway Heights, 5 September: 35.9 µg/m³, 5.4× its usual 6.6Airway Heights, 6 September: 42.3 µg/m³Airway Heights, 7 September: 15.1 µg/m³Airway Heights, 8 September: 7.8 µg/m³Airway Heights, 9 September: 14.8 µg/m³Airway Heights, 10 September: 20.3 µg/m³ProsserProsser, 28 August: 15.9 µg/m³Prosser, 29 August: 12.8 µg/m³Prosser, 30 August: 11.8 µg/m³Prosser, 31 August: 11.8 µg/m³Prosser, 1 September: 14.5 µg/m³Prosser, 2 September: 16.9 µg/m³Prosser, 3 September: 23.2 µg/m³Prosser, 4 September: 26.0 µg/m³, 3.9× its usual 6.7Prosser, 5 September: 34.2 µg/m³, 5.2× its usual 6.6Prosser, 6 September: 40.6 µg/m³Prosser, 7 September: 12.9 µg/m³Prosser, 8 September: 8.8 µg/m³Prosser, 9 September: 5.0 µg/m³Prosser, 10 September: 10.7 µg/m³YrekaYreka, 28 August: 12.9 µg/m³Yreka, 29 August: 22.7 µg/m³Yreka, 30 August: 58.0 µg/m³Yreka, 31 August: 76.4 µg/m³Yreka, 1 September: 55.3 µg/m³Yreka, 2 September: 35.2 µg/m³Yreka, 3 September: 6.1 µg/m³Yreka, 4 September: 9.1 µg/m³Yreka, 5 September: 30.4 µg/m³, 6.1× its usual 4.4Yreka, 6 September: 56.0 µg/m³, 11× its usual 4.1Yreka, 7 September: 25.8 µg/m³, 5.2× its usual 4.1Yreka, 8 September: 9.5 µg/m³Yreka, 9 September: 2.8 µg/m³Yreka, 10 September: 2.3 µg/m³PrinevillePrineville, 28 August: 16.8 µg/m³Prineville, 29 August: 28.1 µg/m³Prineville, 30 August: 18.3 µg/m³Prineville, 31 August: 16.7 µg/m³Prineville, 1 September: 14.7 µg/m³Prineville, 2 September: 12.3 µg/m³Prineville, 3 September: 16.7 µg/m³Prineville, 4 September: 20.3 µg/m³Prineville, 5 September: 55.5 µg/m³, 11× its usual 5.2Prineville, 6 September: 13.0 µg/m³Prineville, 7 September: 16.2 µg/m³Prineville, 8 September: 14.2 µg/m³Prineville, 9 September: 6.3 µg/m³Prineville, 10 September: 5.7 µg/m³Grants PassGrants Pass, 28 August: 7.0 µg/m³Grants Pass, 29 August: 4.5 µg/m³Grants Pass, 30 August: 5.4 µg/m³Grants Pass, 31 August: 4.1 µg/m³Grants Pass, 1 September: 12.3 µg/m³Grants Pass, 2 September: 11.7 µg/m³Grants Pass, 3 September: 16.0 µg/m³Grants Pass, 4 September: 11.5 µg/m³Grants Pass, 5 September: 28.5 µg/m³, 5.7× its usual 4.2Grants Pass, 6 September: 47.3 µg/m³, 9.5× its usual 4.2Grants Pass, 7 September: 41.0 µg/m³, 8.2× its usual 4.2Grants Pass, 8 September: 13.3 µg/m³Grants Pass, 9 September: 6.3 µg/m³Grants Pass, 10 September: 4.5 µg/m³CastlegarCastlegar, 28 August: 14.9 µg/m³Castlegar, 29 August: 15.6 µg/m³Castlegar, 30 August: 11.2 µg/m³Castlegar, 31 August: 12.2 µg/m³Castlegar, 1 September: 14.0 µg/m³Castlegar, 2 September: 14.9 µg/m³Castlegar, 3 September: 16.7 µg/m³Castlegar, 4 September: 22.6 µg/m³Castlegar, 5 September: 44.2 µg/m³, 5.7× its usual 7.7Castlegar, 6 September: 54.2 µg/m³Castlegar, 7 September: 56.1 µg/m³Castlegar, 8 September: 31.6 µg/m³Castlegar, 9 September: 24.3 µg/m³Castlegar, 10 September: 15.0 µg/m³KelownaKelowna, 28 August: 10.9 µg/m³Kelowna, 29 August: 9.2 µg/m³Kelowna, 30 August: 6.9 µg/m³Kelowna, 31 August: 9.4 µg/m³Kelowna, 1 September: 13.0 µg/m³Kelowna, 2 September: 16.8 µg/m³Kelowna, 3 September: 17.1 µg/m³Kelowna, 4 September: 23.2 µg/m³Kelowna, 5 September: 42.7 µg/m³, 5.4× its usual 7.9Kelowna, 6 September: 35.0 µg/m³Kelowna, 7 September: 37.7 µg/m³Kelowna, 8 September: 13.6 µg/m³Kelowna, 9 September: 13.3 µg/m³Kelowna, 10 September: 14.8 µg/m³EllensburgEllensburg, 28 August: 12.6 µg/m³Ellensburg, 29 August: 11.3 µg/m³Ellensburg, 30 August: 9.3 µg/m³Ellensburg, 31 August: 8.5 µg/m³Ellensburg, 1 September: 11.1 µg/m³Ellensburg, 2 September: 11.5 µg/m³Ellensburg, 3 September: 14.8 µg/m³Ellensburg, 4 September: 23.7 µg/m³Ellensburg, 5 September: 40.1 µg/m³, 7.6× its usual 5.3Ellensburg, 6 September: 41.3 µg/m³Ellensburg, 7 September: 7.3 µg/m³Ellensburg, 8 September: 7.7 µg/m³Ellensburg, 9 September: 6.2 µg/m³Ellensburg, 10 September: 11.2 µg/m³QuincyQuincy, 28 August: 6.9 µg/m³Quincy, 29 August: 7.3 µg/m³Quincy, 30 August: 8.0 µg/m³Quincy, 31 August: 11.2 µg/m³Quincy, 1 September: 11.5 µg/m³Quincy, 2 September: 18.8 µg/m³Quincy, 3 September: 16.4 µg/m³Quincy, 4 September: 24.6 µg/m³Quincy, 5 September: 37.5 µg/m³, 6.6× its usual 5.7Quincy, 6 September: 58.8 µg/m³Quincy, 7 September: 19.0 µg/m³Quincy, 8 September: 17.5 µg/m³Quincy, 9 September: 14.9 µg/m³Quincy, 10 September: 20.5 µg/m³LewistonLewiston, 28 August: 19.0 µg/m³Lewiston, 29 August: 14.1 µg/m³Lewiston, 30 August: 14.7 µg/m³Lewiston, 31 August: 18.3 µg/m³Lewiston, 1 September: 13.8 µg/m³Lewiston, 2 September: 15.1 µg/m³Lewiston, 3 September: 14.8 µg/m³Lewiston, 4 September: 17.7 µg/m³Lewiston, 5 September: 35.1 µg/m³, 4.1× its usual 8.6Lewiston, 6 September: 34.8 µg/m³Lewiston, 7 September: 11.8 µg/m³Lewiston, 8 September: 9.6 µg/m³Lewiston, 9 September: 13.1 µg/m³Lewiston, 10 September: 18.4 µg/m³Tri-CitiesTri-Cities, 28 August: no readingTri-Cities, 29 August: no readingTri-Cities, 30 August: no readingTri-Cities, 31 August: no readingTri-Cities, 1 September: no readingTri-Cities, 2 September: no readingTri-Cities, 3 September: 19.8 µg/m³Tri-Cities, 4 September: 19.8 µg/m³Tri-Cities, 5 September: 34.8 µg/m³, 7.0× its usual 4.8Tri-Cities, 6 September: 40.2 µg/m³Tri-Cities, 7 September: 15.1 µg/m³Tri-Cities, 8 September: 8.4 µg/m³Tri-Cities, 9 September: 6.0 µg/m³Tri-Cities, 10 September: 10.2 µg/m³MoscowMoscow, 28 August: 13.3 µg/m³Moscow, 29 August: 12.1 µg/m³Moscow, 30 August: 15.0 µg/m³Moscow, 31 August: 17.4 µg/m³Moscow, 1 September: 13.7 µg/m³Moscow, 2 September: 18.5 µg/m³Moscow, 3 September: 18.1 µg/m³Moscow, 4 September: 18.8 µg/m³Moscow, 5 September: 34.5 µg/m³, 4.7× its usual 7.3Moscow, 6 September: 29.1 µg/m³Moscow, 7 September: 12.2 µg/m³Moscow, 8 September: 11.0 µg/m³Moscow, 9 September: 15.3 µg/m³Moscow, 10 September: 16.5 µg/m³PullmanPullman, 28 August: 13.2 µg/m³Pullman, 29 August: 12.2 µg/m³Pullman, 30 August: 14.2 µg/m³Pullman, 31 August: 17.1 µg/m³Pullman, 1 September: 13.2 µg/m³Pullman, 2 September: 17.3 µg/m³Pullman, 3 September: 14.7 µg/m³Pullman, 4 September: 15.8 µg/m³Pullman, 5 September: 34.2 µg/m³, 5.6× its usual 6.1Pullman, 6 September: 31.4 µg/m³Pullman, 7 September: 11.2 µg/m³Pullman, 8 September: 9.4 µg/m³Pullman, 9 September: 10.4 µg/m³Pullman, 10 September: 14.3 µg/m³AshlandAshland, 28 August: 7.1 µg/m³Ashland, 29 August: 8.2 µg/m³Ashland, 30 August: 12.0 µg/m³Ashland, 31 August: 11.0 µg/m³Ashland, 1 September: 10.0 µg/m³Ashland, 2 September: 12.8 µg/m³Ashland, 3 September: 8.3 µg/m³Ashland, 4 September: 14.3 µg/m³Ashland, 5 September: 22.7 µg/m³Ashland, 6 September: 39.5 µg/m³, 7.9× its usual 5.0Ashland, 7 September: 25.5 µg/m³, 5.1× its usual 4.9Ashland, 8 September: 19.6 µg/m³Ashland, 9 September: 4.1 µg/m³Ashland, 10 September: 4.6 µg/m³TalentTalent, 28 August: 6.5 µg/m³Talent, 29 August: 7.0 µg/m³Talent, 30 August: 11.3 µg/m³Talent, 31 August: 8.4 µg/m³Talent, 1 September: 9.2 µg/m³Talent, 2 September: 11.8 µg/m³Talent, 3 September: 8.6 µg/m³Talent, 4 September: 14.2 µg/m³Talent, 5 September: 22.8 µg/m³Talent, 6 September: 34.5 µg/m³, 6.9× its usual 4.6Talent, 7 September: 24.9 µg/m³Talent, 8 September: 21.2 µg/m³Talent, 9 September: 3.3 µg/m³Talent, 10 September: 4.2 µg/m³28 Aug301 Sep3579
The 60 cities with the highest readings of 94, 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
SquamishBritish Columbia, Canada3 173.03 September7.025×
Fort St. JohnBritish Columbia, Canada3 140.01 September6.223×
Grande PrairieAlberta, Canada4 166.01 September8.220×
West VancouverBritish Columbia, Canada2 87.23 September5.217×
Sherwood ParkAlberta, Canada5 126.01 September8.016×
St. AlbertAlberta, Canada5 126.01 September8.215×
Fort SaskatchewanAlberta, Canada5 135.01 September9.514×
EdmontonAlberta, Canada5 140.01 September11.412×
HopeBritish Columbia, Canada3 69.15 September5.912×
WhistlerBritish Columbia, Canada3 56.35 September4.611×
YrekaCalifornia, United States3 56.06 September4.111×
WenatcheeWashington, United States2 58.25 September5.411×
PrinevilleOregon, United States1 55.55 September5.211×
EdsonAlberta, Canada4 71.12 September7.010×
CalgaryAlberta, Canada4 100.32 September10.19.9×
Grants PassOregon, United States3 47.36 September4.29.5×
YakimaWashington, United States2 58.04 September6.29.4×
LethbridgeAlberta, Canada4 72.82 September7.99.2×
EphrataWashington, United States2 53.95 September6.48.4×
AshlandOregon, United States2 39.56 September5.07.9×
KirklandWashington, United States2 38.85 September3.57.8×
GibsonsBritish Columbia, Canada3 48.73 September6.47.6×
EllensburgWashington, United States1 40.15 September5.37.6×
Inglewood-Finn HillWashington, United States2 37.55 September4.17.5×
CoquitlamBritish Columbia, Canada1 40.13 September5.47.4×
SmithersBritish Columbia, Canada3 36.65 September4.47.3×
Drayton ValleyAlberta, Canada3 57.21 September8.17.1×
Williams LakeBritish Columbia, Canada3 35.74 September4.77.1×
Tri-CitiesWashington, United States1 34.85 September4.87.0×
Fort McMurrayAlberta, Canada4 96.331 August13.96.9×
BurnabyBritish Columbia, Canada1 37.53 September5.46.9×
MeadWashington, United States3 37.35 September5.46.9×
North VancouverBritish Columbia, Canada1 35.13 September5.16.9×
TalentOregon, United States1 34.56 September4.66.9×
Prince GeorgeBritish Columbia, Canada5 64.25 September9.66.7×
Medicine HatAlberta, Canada3 48.02 September7.26.7×
QuincyWashington, United States1 37.55 September5.76.6×
Swift CurrentSaskatchewan, Canada3 53.42 September8.26.5×
ToppenishWashington, United States3 48.25 September7.56.4×
Strawberry HillBritish Columbia, Canada1 34.83 September5.46.4×
VancouverBritish Columbia, Canada1 34.53 September5.46.4×
MissionBritish Columbia, Canada3 32.33 September5.16.3×
Red DeerAlberta, Canada4 58.62 September9.46.2×
Spokane ValleyWashington, United States3 37.25 September6.16.1×
GlendiveMontana, United States1 32.72 September5.46.1×
Port CoquitlamBritish Columbia, Canada1 31.03 September5.16.1×
Grand CentreAlberta, Canada4 56.52 September9.46.0×
ShorelineWashington, United States1 33.75 September5.66.0×
MedfordOregon, United States3 32.06 September5.36.0×
Idaho FallsIdaho, United States1 29.35 September4.55.9×
AgassizBritish Columbia, Canada3 37.04 September6.45.8×
CastlegarBritish Columbia, Canada1 44.25 September7.75.7×
SpokaneWashington, United States3 37.75 September6.65.7×
BoiseIdaho, United States1 29.85 September5.25.7×
PullmanWashington, United States1 34.25 September6.15.6×
KelownaBritish Columbia, Canada1 42.75 September7.95.4×
Coeur d'AleneIdaho, United States2 37.75 September7.05.4×
Airway HeightsWashington, United States2 35.95 September6.65.4×
OntarioOregon, United States1 26.95 September4.95.4×
AirdrieAlberta, Canada1 41.94 September7.95.3×
ProsserWashington, United States2 34.25 September6.65.2×
HermistonOregon, United States1 31.45 September6.05.2×
HavreMontana, United States1 26.03 September5.05.2×
SaskatoonSaskatchewan, Canada2 55.31 September10.95.1×
VernonBritish Columbia, Canada2 42.45 September8.35.1×
MissoulaMontana, United States1 27.64 September5.45.1×
AbbotsfordBritish Columbia, Canada1 29.73 September6.05.0×
SandpointIdaho, United States3 38.85 September7.94.9×
MeridianIdaho, United States1 30.15 September6.24.9×
MoscowIdaho, United States1 34.55 September7.34.7×
ChilliwackBritish Columbia, Canada3 31.33 September6.64.7×
BillingsMontana, United States2 31.13 September6.74.6×
LockwoodMontana, United States2 31.13 September6.74.6×
Walla WallaWashington, United States1 27.15 September5.94.6×
CrestonBritish Columbia, Canada2 26.74 September5.94.5×
BozemanMontana, United States1 26.24 September5.84.5×
LewistownMontana, United States2 27.24 September6.24.4×
NampaIdaho, United States1 30.55 September7.14.3×
RexburgIdaho, United States1 29.75 September7.04.2×
LewistonIdaho, United States1 35.15 September8.64.1×
Baker CityOregon, United States1 27.05 September6.84.0×
Moses LakeWashington, United States2 26.54 September6.74.0×
QuesnelBritish Columbia, Canada4 35.73 September9.13.9×
Columbia FallsMontana, United States3 27.95 September7.23.9×
CranbrookBritish Columbia, Canada2 25.55 September6.73.8×
HelenaMontana, United States2 27.94 September7.73.6×
Helena Valley West CentralMontana, United States2 27.94 September7.73.6×
KamloopsBritish Columbia, Canada2 33.34 September9.63.5×
Prince AlbertSaskatchewan, Canada1 38.81 September11.53.4×
ReginaSaskatchewan, Canada1 33.92 September10.23.3×
SunnysideWashington, United States1 25.93 September7.83.3×
WeiserIdaho, United States1 26.35 September9.02.9×
Great FallsMontana, United States2 33.03 September11.62.8×
EstevanSaskatchewan, Canada1 26.62 September10.92.4×

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 15 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, North-western United States and Canada, August and September 2025: 94 cities with PM2.5 at twice their usual or more, 31 August to 7 September 2025, smogrank.com/episodes/2025-08-north-western-united-states-and-canada (accessed 5 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. Fire detections from NASA FIRMS; smoke maps from NOAA HMS.