SmogRank / Episodes / United States

North-western United States and Canada, September 2025

For 10 days, from 1 to 10 September 2025, 54 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.

No cause namedWe have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached54in 2 countries
Days101 to 10 September 2025
Worst day5 September30 cities counted
Furthest above usual25×Squamish

Day by day

5 September 30 cities at twice their usual or more
PendletonPocatelloCondaThe DallesSheridanBellevueRentonAuburnPicnic Point-North LynnwoodColumbia CityMount VernonRedmondSeattleBurienBellinghamTacomaParklandBendAnacortesOak HarborLangleyBremertonLaceyGreshamDeltaSalmon CreekVancouverCentraliaRichmondOregon CityMilwaukiePortlandPrince AlbertLongviewCanbyGilletteTigardBeavertonVictoriaCasperPort AngelesHillsboroWoodburnLangfordForest GroveNorth CowichanDuncanSalemMcMinnvilleAlbanyAberdeenNanaimoHarewoodDallasCorvallisEugenePrince GeorgeRoseburgCoos BayRapid CitySaskatoonGreat FallsReginaKamloopsHelenaMoses LakeLewistonRexburgNampaBozemanWalla WallaBillingsMoscowChilliwackMeridianAbbotsfordVernonHermistonAirdrieKelownaCoeur d'AleneBoisePullmanSunnysideIdaho FallsShorelineButtePort CoquitlamRed DeerMissoulaMissionVancouverStrawberry HillSwift CurrentSpokane ValleySpokaneMedicine HatNorth VancouverBurnabyCoquitlamInglewood-Finn HillKirklandEllensburgTri-CitiesCranbrookYakimaLethbridgeCalgaryEdmontonSt. AlbertSherwood ParkWenatcheeWest VancouverSquamish
29 Aug30311 Sep2345678910111213
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, 29 August: 27.1 µg/m³, 2.4× usualEdmonton, 30 August: 18.4 µg/m³, 1.6× usualEdmonton, 31 August: 76.6 µg/m³, 6.7× usualEdmonton, 1 September: 140.0 µg/m³, 12× usualEdmonton, 2 September: 46.6 µg/m³, 4.1× usualEdmonton, 3 September: 48.2 µg/m³, 4.2× usualEdmonton, 4 September: 36.8 µg/m³, 3.2× usualEdmonton, 5 September: 14.3 µg/m³, 1.3× usualEdmonton, 6 September: 22.4 µg/m³, 2.0× usualEdmonton, 7 September: 36.8 µg/m³, 3.2× usualEdmonton, 8 September: 39.1 µg/m³, 3.4× usualEdmonton, 9 September: 45.1 µg/m³, 4.0× usualEdmonton, 10 September: 35.3 µg/m³, 3.1× usualEdmonton, 11 September: 28.5 µg/m³, 2.5× usualEdmonton, 12 September: 25.3 µg/m³, 2.2× usualEdmonton, 13 September: 22.0 µg/m³, 1.9× usualSherwood ParkSherwood Park, 29 August: 19.2 µg/m³, 2.4× usualSherwood Park, 30 August: 10.1 µg/m³, 1.3× usualSherwood Park, 31 August: 58.0 µg/m³, 7.3× usualSherwood Park, 1 September: 126.0 µg/m³, 16× usualSherwood Park, 2 September: 41.9 µg/m³, 5.2× usualSherwood Park, 3 September: 42.7 µg/m³, 5.3× usualSherwood Park, 4 September: 32.7 µg/m³, 4.1× usualSherwood Park, 5 September: 10.3 µg/m³, 1.3× usualSherwood Park, 6 September: 16.4 µg/m³, 2.1× usualSherwood Park, 7 September: 26.1 µg/m³, 3.3× usualSherwood Park, 8 September: 27.2 µg/m³, 3.4× usualSherwood Park, 9 September: 34.6 µg/m³, 4.3× usualSherwood Park, 10 September: 28.8 µg/m³, 3.6× usualSherwood Park, 11 September: 21.4 µg/m³, 2.7× usualSherwood Park, 12 September: 18.7 µg/m³, 2.3× usualSherwood Park, 13 September: 16.5 µg/m³, 2.1× usualSt. AlbertSt. Albert, 29 August: 21.5 µg/m³, 2.6× usualSt. Albert, 30 August: 16.0 µg/m³, 2.0× usualSt. Albert, 31 August: 52.9 µg/m³, 6.5× usualSt. Albert, 1 September: 126.0 µg/m³, 15× usualSt. Albert, 2 September: 42.4 µg/m³, 5.2× usualSt. Albert, 3 September: 44.2 µg/m³, 5.4× usualSt. Albert, 4 September: 33.6 µg/m³, 4.1× usualSt. Albert, 5 September: 15.4 µg/m³, 1.9× usualSt. Albert, 6 September: 21.3 µg/m³, 2.6× usualSt. Albert, 7 September: 27.7 µg/m³, 3.4× usualSt. Albert, 8 September: 27.6 µg/m³, 3.4× usualSt. Albert, 9 September: 36.4 µg/m³, 4.4× usualSt. Albert, 10 September: 24.9 µg/m³, 3.0× usualSt. Albert, 11 September: 20.7 µg/m³, 2.5× usualSt. Albert, 12 September: 26.5 µg/m³, 3.2× usualSt. Albert, 13 September: 19.3 µg/m³, 2.4× usualSaskatoonSaskatoon, 29 August: 16.3 µg/m³, 1.6× usualSaskatoon, 30 August: 9.3 µg/m³, 0.9× usualSaskatoon, 31 August: 8.3 µg/m³, 0.8× usualSaskatoon, 1 September: 55.3 µg/m³, 5.3× usualSaskatoon, 2 September: 26.0 µg/m³, 2.5× usualSaskatoon, 3 September: no readingSaskatoon, 4 September: 14.4 µg/m³, 1.4× usualSaskatoon, 5 September: 6.0 µg/m³, 0.6× usualSaskatoon, 6 September: 9.4 µg/m³, 0.9× usualSaskatoon, 7 September: 11.0 µg/m³, 1.0× usualSaskatoon, 8 September: 29.8 µg/m³, 2.8× usualSaskatoon, 9 September: 31.6 µg/m³, 3.0× usualSaskatoon, 10 September: 22.2 µg/m³, 2.1× usualSaskatoon, 11 September: 25.0 µg/m³, 2.4× usualSaskatoon, 12 September: 31.9 µg/m³, 3.0× usualSaskatoon, 13 September: 7.4 µg/m³, 0.7× usualRed DeerRed Deer, 29 August: 14.0 µg/m³, 1.5× usualRed Deer, 30 August: 10.9 µg/m³, 1.2× usualRed Deer, 31 August: 10.7 µg/m³, 1.1× usualRed Deer, 1 September: 54.1 µg/m³, 5.8× usualRed Deer, 2 September: 58.6 µg/m³, 6.2× usualRed Deer, 3 September: 46.8 µg/m³, 5.0× usualRed Deer, 4 September: 35.7 µg/m³, 3.8× usualRed Deer, 5 September: 23.7 µg/m³, 2.5× usualRed Deer, 6 September: 21.7 µg/m³, 2.3× usualRed Deer, 7 September: 24.4 µg/m³, 2.6× usualRed Deer, 8 September: 28.4 µg/m³, 3.0× usualRed Deer, 9 September: 30.5 µg/m³, 3.2× usualRed Deer, 10 September: 26.5 µg/m³, 2.8× usualRed Deer, 11 September: 22.2 µg/m³, 2.4× usualRed Deer, 12 September: 21.1 µg/m³, 2.2× usualRed Deer, 13 September: 13.0 µg/m³, 1.4× usualSwift CurrentSwift Current, 29 August: 7.3 µg/m³, 0.9× usualSwift Current, 30 August: 6.0 µg/m³, 0.7× usualSwift Current, 31 August: 6.3 µg/m³, 0.8× usualSwift Current, 1 September: 37.5 µg/m³, 4.6× usualSwift Current, 2 September: 53.4 µg/m³, 6.5× usualSwift Current, 3 September: 19.7 µg/m³, 2.4× usualSwift Current, 4 September: 26.2 µg/m³, 3.2× usualSwift Current, 5 September: 8.0 µg/m³, 1.0× usualSwift Current, 6 September: 5.6 µg/m³, 0.7× usualSwift Current, 7 September: 8.8 µg/m³, 1.1× usualSwift Current, 8 September: 19.3 µg/m³, 2.4× usualSwift Current, 9 September: 20.1 µg/m³, 2.5× usualSwift Current, 10 September: 16.8 µg/m³, 2.0× usualSwift Current, 11 September: 17.1 µg/m³, 2.1× usualSwift Current, 12 September: 18.1 µg/m³, 2.2× usualSwift Current, 13 September: 7.0 µg/m³, 0.9× usualCalgaryCalgary, 29 August: 12.7 µg/m³, 1.3× usualCalgary, 30 August: 12.5 µg/m³, 1.2× usualCalgary, 31 August: 12.9 µg/m³, 1.3× usualCalgary, 1 September: 20.2 µg/m³, 2.0× usualCalgary, 2 September: 100.3 µg/m³, 9.9× usualCalgary, 3 September: 57.2 µg/m³, 5.7× usualCalgary, 4 September: 47.8 µg/m³, 4.7× usualCalgary, 5 September: 37.0 µg/m³, 3.7× usualCalgary, 6 September: 31.2 µg/m³, 3.1× usualCalgary, 7 September: 33.7 µg/m³, 3.3× usualCalgary, 8 September: 32.1 µg/m³, 3.2× usualCalgary, 9 September: 30.8 µg/m³, 3.0× usualCalgary, 10 September: 25.2 µg/m³, 2.5× usualCalgary, 11 September: 16.9 µg/m³, 1.7× usualCalgary, 12 September: 22.5 µg/m³, 2.2× usualCalgary, 13 September: 15.2 µg/m³, 1.5× usualLethbridgeLethbridge, 29 August: 7.9 µg/m³, 1.0× usualLethbridge, 30 August: 8.3 µg/m³, 1.1× usualLethbridge, 31 August: 11.4 µg/m³, 1.4× usualLethbridge, 1 September: 20.7 µg/m³, 2.6× usualLethbridge, 2 September: 72.8 µg/m³, 9.2× usualLethbridge, 3 September: 62.0 µg/m³, 7.8× usualLethbridge, 4 September: 40.9 µg/m³, 5.2× usualLethbridge, 5 September: 30.6 µg/m³, 3.9× usualLethbridge, 6 September: 19.8 µg/m³, 2.5× usualLethbridge, 7 September: 39.5 µg/m³, 5.0× usualLethbridge, 8 September: 31.1 µg/m³, 3.9× usualLethbridge, 9 September: 18.3 µg/m³, 2.3× usualLethbridge, 10 September: 14.8 µg/m³, 1.9× usualLethbridge, 11 September: 15.5 µg/m³, 2.0× usualLethbridge, 12 September: 10.9 µg/m³, 1.4× usualLethbridge, 13 September: 9.3 µg/m³, 1.2× usualMedicine HatMedicine Hat, 29 August: 7.0 µg/m³, 1.0× usualMedicine Hat, 30 August: 8.7 µg/m³, 1.2× usualMedicine Hat, 31 August: 9.9 µg/m³, 1.4× usualMedicine Hat, 1 September: 14.4 µg/m³, 2.0× usualMedicine Hat, 2 September: 48.0 µg/m³, 6.7× usualMedicine Hat, 3 September: 33.8 µg/m³, 4.7× usualMedicine Hat, 4 September: 27.5 µg/m³, 3.8× usualMedicine Hat, 5 September: 10.4 µg/m³, 1.4× usualMedicine Hat, 6 September: 6.9 µg/m³, 1.0× usualMedicine Hat, 7 September: 16.8 µg/m³, 2.3× usualMedicine Hat, 8 September: 18.6 µg/m³, 2.6× usualMedicine Hat, 9 September: 19.8 µg/m³, 2.8× usualMedicine Hat, 10 September: 15.9 µg/m³, 2.2× usualMedicine Hat, 11 September: 14.8 µg/m³, 2.1× usualMedicine Hat, 12 September: 12.8 µg/m³, 1.8× usualMedicine Hat, 13 September: 6.7 µg/m³, 0.9× usualReginaRegina, 29 August: 17.0 µg/m³, 1.7× usualRegina, 30 August: 13.9 µg/m³, 1.4× usualRegina, 31 August: 10.5 µg/m³, 1.0× usualRegina, 1 September: 24.5 µg/m³, 2.4× usualRegina, 2 September: 33.9 µg/m³, 3.3× usualRegina, 3 September: 11.0 µg/m³, 1.1× usualRegina, 4 September: 10.2 µg/m³, 1.0× usualRegina, 5 September: 4.6 µg/m³, 0.5× usualRegina, 6 September: 11.0 µg/m³, 1.1× usualRegina, 7 September: 8.0 µg/m³, 0.8× usualRegina, 8 September: 15.8 µg/m³, 1.5× usualRegina, 9 September: 22.8 µg/m³, 2.2× usualRegina, 10 September: 16.5 µg/m³, 1.6× usualRegina, 11 September: 15.0 µg/m³, 1.5× usualRegina, 12 September: 11.9 µg/m³, 1.2× usualRegina, 13 September: 5.6 µg/m³, 0.5× usualMoses LakeMoses Lake, 29 August: 12.7 µg/m³, 1.9× usualMoses Lake, 30 August: 12.8 µg/m³, 1.9× usualMoses Lake, 31 August: 17.6 µg/m³, 2.6× usualMoses Lake, 1 September: 15.5 µg/m³, 2.3× usualMoses Lake, 2 September: 31.9 µg/m³, 4.8× usualMoses Lake, 3 September: 25.1 µg/m³, 3.7× usualMoses Lake, 4 September: 26.5 µg/m³, 4.0× usualMoses Lake, 5 September: no readingMoses Lake, 6 September: no readingMoses Lake, 7 September: no readingMoses Lake, 8 September: no readingMoses Lake, 9 September: 8.6 µg/m³, 1.3× usualMoses Lake, 10 September: 16.5 µg/m³, 2.5× usualMoses Lake, 11 September: 14.6 µg/m³, 2.2× usualMoses Lake, 12 September: 13.8 µg/m³, 2.1× usualMoses Lake, 13 September: 13.6 µg/m³, 2.0× usualSquamishSquamish, 29 August: 15.9 µg/m³, 2.3× usualSquamish, 30 August: 13.2 µg/m³, 1.9× usualSquamish, 31 August: 20.9 µg/m³, 3.0× usualSquamish, 1 September: 12.1 µg/m³, 1.7× usualSquamish, 2 September: 17.0 µg/m³, 2.4× usualSquamish, 3 September: 173.0 µg/m³, 25× usualSquamish, 4 September: 53.1 µg/m³, 7.6× usualSquamish, 5 September: 43.1 µg/m³, 6.2× usualSquamish, 6 September: 49.3 µg/m³, 7.0× usualSquamish, 7 September: 11.8 µg/m³, 1.7× usualSquamish, 8 September: 8.2 µg/m³, 1.2× usualSquamish, 9 September: 9.4 µg/m³, 1.3× usualSquamish, 10 September: 7.7 µg/m³, 1.1× usualSquamish, 11 September: 8.6 µg/m³, 1.2× usualSquamish, 12 September: 7.6 µg/m³, 1.1× usualSquamish, 13 September: 8.8 µg/m³, 1.3× usualWest VancouverWest Vancouver, 29 August: 14.3 µg/m³, 2.8× usualWest Vancouver, 30 August: 8.8 µg/m³, 1.7× usualWest Vancouver, 31 August: 12.9 µg/m³, 2.5× usualWest Vancouver, 1 September: 8.3 µg/m³, 1.6× usualWest Vancouver, 2 September: 9.7 µg/m³, 1.9× usualWest Vancouver, 3 September: 87.2 µg/m³, 17× usualWest Vancouver, 4 September: 21.8 µg/m³, 4.2× usualWest Vancouver, 5 September: 31.4 µg/m³, 6.0× usualWest Vancouver, 6 September: 28.1 µg/m³, 5.4× usualWest Vancouver, 7 September: 9.6 µg/m³, 1.8× usualWest Vancouver, 8 September: 6.7 µg/m³, 1.3× usualWest Vancouver, 9 September: 7.3 µg/m³, 1.4× usualWest Vancouver, 10 September: 5.0 µg/m³, 1.0× usualWest Vancouver, 11 September: 6.7 µg/m³, 1.3× usualWest Vancouver, 12 September: 6.0 µg/m³, 1.2× usualWest Vancouver, 13 September: 6.1 µg/m³, 1.2× usualCoquitlamCoquitlam, 29 August: 12.8 µg/m³, 2.4× usualCoquitlam, 30 August: 8.7 µg/m³, 1.6× usualCoquitlam, 31 August: 11.0 µg/m³, 2.0× usualCoquitlam, 1 September: 8.7 µg/m³, 1.6× usualCoquitlam, 2 September: 11.9 µg/m³, 2.2× usualCoquitlam, 3 September: 40.1 µg/m³, 7.4× usualCoquitlam, 4 September: 21.5 µg/m³, 4.0× usualCoquitlam, 5 September: 21.9 µg/m³, 4.1× usualCoquitlam, 6 September: 16.6 µg/m³, 3.1× usualCoquitlam, 7 September: 7.1 µg/m³, 1.3× usualCoquitlam, 8 September: 6.8 µg/m³, 1.3× usualCoquitlam, 9 September: 8.0 µg/m³, 1.5× usualCoquitlam, 10 September: 5.6 µg/m³, 1.0× usualCoquitlam, 11 September: 7.3 µg/m³, 1.4× usualCoquitlam, 12 September: 4.8 µg/m³, 0.9× usualCoquitlam, 13 September: 5.6 µg/m³, 1.0× usualBurnabyBurnaby, 29 August: 14.4 µg/m³, 2.7× usualBurnaby, 30 August: 8.4 µg/m³, 1.6× usualBurnaby, 31 August: 10.8 µg/m³, 2.0× usualBurnaby, 1 September: 8.0 µg/m³, 1.5× usualBurnaby, 2 September: 12.1 µg/m³, 2.2× usualBurnaby, 3 September: 37.5 µg/m³, 6.9× usualBurnaby, 4 September: 11.7 µg/m³, 2.2× usualBurnaby, 5 September: 18.1 µg/m³, 3.4× usualBurnaby, 6 September: 13.7 µg/m³, 2.5× usualBurnaby, 7 September: 7.1 µg/m³, 1.3× usualBurnaby, 8 September: 6.6 µg/m³, 1.2× usualBurnaby, 9 September: 8.3 µg/m³, 1.5× usualBurnaby, 10 September: 5.1 µg/m³, 0.9× usualBurnaby, 11 September: 7.3 µg/m³, 1.4× usualBurnaby, 12 September: 4.9 µg/m³, 0.9× usualBurnaby, 13 September: 5.6 µg/m³, 1.0× usualNorth VancouverNorth Vancouver, 29 August: 11.3 µg/m³, 2.2× usualNorth Vancouver, 30 August: 7.1 µg/m³, 1.4× usualNorth Vancouver, 31 August: 10.5 µg/m³, 2.1× usualNorth Vancouver, 1 September: 7.8 µg/m³, 1.5× usualNorth Vancouver, 2 September: 8.5 µg/m³, 1.7× usualNorth Vancouver, 3 September: 35.1 µg/m³, 6.9× usualNorth Vancouver, 4 September: 17.8 µg/m³, 3.5× usualNorth Vancouver, 5 September: 23.2 µg/m³, 4.5× usualNorth Vancouver, 6 September: 18.0 µg/m³, 3.5× usualNorth Vancouver, 7 September: 7.1 µg/m³, 1.4× usualNorth Vancouver, 8 September: 5.4 µg/m³, 1.1× usualNorth Vancouver, 9 September: 6.4 µg/m³, 1.3× usualNorth Vancouver, 10 September: 4.7 µg/m³, 0.9× usualNorth Vancouver, 11 September: 7.2 µg/m³, 1.4× usualNorth Vancouver, 12 September: 5.4 µg/m³, 1.1× usualNorth Vancouver, 13 September: 5.1 µg/m³, 1.0× usualStrawberry HillStrawberry Hill, 29 August: 11.4 µg/m³, 2.1× usualStrawberry Hill, 30 August: 7.4 µg/m³, 1.4× usualStrawberry Hill, 31 August: 10.3 µg/m³, 1.9× usualStrawberry Hill, 1 September: 7.1 µg/m³, 1.3× usualStrawberry Hill, 2 September: 10.5 µg/m³, 1.9× usualStrawberry Hill, 3 September: 34.8 µg/m³, 6.4× usualStrawberry Hill, 4 September: 11.8 µg/m³, 2.2× usualStrawberry Hill, 5 September: 18.2 µg/m³, 3.4× usualStrawberry Hill, 6 September: 10.7 µg/m³, 2.0× usualStrawberry Hill, 7 September: 6.3 µg/m³, 1.2× usualStrawberry Hill, 8 September: 6.1 µg/m³, 1.1× usualStrawberry Hill, 9 September: 8.5 µg/m³, 1.6× usualStrawberry Hill, 10 September: 4.7 µg/m³, 0.9× usualStrawberry Hill, 11 September: 6.1 µg/m³, 1.1× usualStrawberry Hill, 12 September: 4.4 µg/m³, 0.8× usualStrawberry Hill, 13 September: 5.3 µg/m³, 1.0× usualVancouverVancouver, 29 August: 14.5 µg/m³, 2.7× usualVancouver, 30 August: 8.5 µg/m³, 1.6× usualVancouver, 31 August: 11.4 µg/m³, 2.1× usualVancouver, 1 September: 8.7 µg/m³, 1.6× usualVancouver, 2 September: 9.6 µg/m³, 1.8× usualVancouver, 3 September: 34.5 µg/m³, 6.4× usualVancouver, 4 September: 12.4 µg/m³, 2.3× usualVancouver, 5 September: 21.5 µg/m³, 4.0× usualVancouver, 6 September: 13.6 µg/m³, 2.5× usualVancouver, 7 September: 7.7 µg/m³, 1.4× usualVancouver, 8 September: 6.6 µg/m³, 1.2× usualVancouver, 9 September: 7.4 µg/m³, 1.4× usualVancouver, 10 September: 4.7 µg/m³, 0.9× usualVancouver, 11 September: 7.2 µg/m³, 1.3× usualVancouver, 12 September: 5.5 µg/m³, 1.0× usualVancouver, 13 September: 6.9 µg/m³, 1.3× usualGreat FallsGreat Falls, 29 August: 10.2 µg/m³, 0.9× usualGreat Falls, 30 August: 8.7 µg/m³, 0.8× usualGreat Falls, 31 August: 15.6 µg/m³, 1.3× usualGreat Falls, 1 September: 17.1 µg/m³, 1.5× usualGreat Falls, 2 September: 20.5 µg/m³, 1.8× usualGreat Falls, 3 September: 33.0 µg/m³, 2.8× usualGreat Falls, 4 September: 29.7 µg/m³, 2.6× usualGreat Falls, 5 September: no readingGreat Falls, 6 September: no readingGreat Falls, 7 September: 30.6 µg/m³, 2.6× usualGreat Falls, 8 September: 16.3 µg/m³, 1.4× usualGreat Falls, 9 September: 14.5 µg/m³, 1.3× usualGreat Falls, 10 September: 11.7 µg/m³, 1.0× usualGreat Falls, 11 September: 13.2 µg/m³, 1.1× usualGreat Falls, 12 September: 9.6 µg/m³, 0.8× usualGreat Falls, 13 September: 9.1 µg/m³, 0.8× usualMissionMission, 29 August: 14.0 µg/m³, 2.7× usualMission, 30 August: 10.0 µg/m³, 2.0× usualMission, 31 August: 11.6 µg/m³, 2.3× usualMission, 1 September: 10.9 µg/m³, 2.1× usualMission, 2 September: 12.6 µg/m³, 2.5× usualMission, 3 September: 32.3 µg/m³, 6.3× usualMission, 4 September: 26.9 µg/m³, 5.3× usualMission, 5 September: 29.6 µg/m³, 5.8× usualMission, 6 September: 18.7 µg/m³, 3.7× usualMission, 7 September: 7.3 µg/m³, 1.4× usualMission, 8 September: 7.6 µg/m³, 1.5× usualMission, 9 September: 11.8 µg/m³, 2.3× usualMission, 10 September: 8.0 µg/m³, 1.6× usualMission, 11 September: 8.3 µg/m³, 1.6× usualMission, 12 September: 4.7 µg/m³, 0.9× usualMission, 13 September: 5.8 µg/m³, 1.1× usualChilliwackChilliwack, 29 August: 14.6 µg/m³, 2.2× usualChilliwack, 30 August: 10.7 µg/m³, 1.6× usualChilliwack, 31 August: 12.6 µg/m³, 1.9× usualChilliwack, 1 September: 11.7 µg/m³, 1.8× usualChilliwack, 2 September: 13.4 µg/m³, 2.0× usualChilliwack, 3 September: 31.3 µg/m³, 4.7× usualChilliwack, 4 September: 25.2 µg/m³, 3.8× usualChilliwack, 5 September: 28.9 µg/m³, 4.4× usualChilliwack, 6 September: 16.0 µg/m³, 2.4× usualChilliwack, 7 September: 8.2 µg/m³, 1.2× usualChilliwack, 8 September: 8.7 µg/m³, 1.3× usualChilliwack, 9 September: 10.6 µg/m³, 1.6× usualChilliwack, 10 September: 9.4 µg/m³, 1.4× usualChilliwack, 11 September: 8.6 µg/m³, 1.3× usualChilliwack, 12 September: 6.4 µg/m³, 1.0× usualChilliwack, 13 September: 6.3 µg/m³, 1.0× usualBillingsBillings, 29 August: 5.1 µg/m³, 0.8× usualBillings, 30 August: 6.8 µg/m³, 1.0× usualBillings, 31 August: 7.7 µg/m³, 1.1× usualBillings, 1 September: 11.4 µg/m³, 1.7× usualBillings, 2 September: 12.3 µg/m³, 1.8× usualBillings, 3 September: 31.1 µg/m³, 4.6× usualBillings, 4 September: 26.2 µg/m³, 3.9× usualBillings, 5 September: 12.4 µg/m³, 1.9× usualBillings, 6 September: 11.1 µg/m³, 1.7× usualBillings, 7 September: 13.1 µg/m³, 2.0× usualBillings, 8 September: 12.6 µg/m³, 1.9× usualBillings, 9 September: 16.3 µg/m³, 2.4× usualBillings, 10 September: 7.6 µg/m³, 1.1× usualBillings, 11 September: no readingBillings, 12 September: no readingBillings, 13 September: 4.1 µg/m³, 0.6× usualPort CoquitlamPort Coquitlam, 29 August: 12.5 µg/m³, 2.5× usualPort Coquitlam, 30 August: 9.0 µg/m³, 1.8× usualPort Coquitlam, 31 August: 10.0 µg/m³, 2.0× usualPort Coquitlam, 1 September: 8.3 µg/m³, 1.6× usualPort Coquitlam, 2 September: 10.1 µg/m³, 2.0× usualPort Coquitlam, 3 September: 31.0 µg/m³, 6.1× usualPort Coquitlam, 4 September: 16.7 µg/m³, 3.3× usualPort Coquitlam, 5 September: 20.5 µg/m³, 4.0× usualPort Coquitlam, 6 September: 16.2 µg/m³, 3.2× usualPort Coquitlam, 7 September: 6.5 µg/m³, 1.3× usualPort Coquitlam, 8 September: 7.4 µg/m³, 1.5× usualPort Coquitlam, 9 September: 8.5 µg/m³, 1.7× usualPort Coquitlam, 10 September: 6.0 µg/m³, 1.2× usualPort Coquitlam, 11 September: 6.6 µg/m³, 1.3× usualPort Coquitlam, 12 September: 4.3 µg/m³, 0.8× usualPort Coquitlam, 13 September: 4.8 µg/m³, 0.9× usualSpokaneSpokane, 29 August: 11.9 µg/m³, 1.8× usualSpokane, 30 August: 15.0 µg/m³, 2.3× usualSpokane, 31 August: 18.9 µg/m³, 2.9× usualSpokane, 1 September: 15.2 µg/m³, 2.3× usualSpokane, 2 September: 19.2 µg/m³, 2.9× usualSpokane, 3 September: 30.0 µg/m³, 4.5× usualSpokane, 4 September: 31.6 µg/m³, 4.8× usualSpokane, 5 September: 37.7 µg/m³, 5.7× usualSpokane, 6 September: 43.5 µg/m³, 6.6× usualSpokane, 7 September: 16.0 µg/m³, 2.4× usualSpokane, 8 September: 8.2 µg/m³, 1.2× usualSpokane, 9 September: 14.2 µg/m³, 2.2× usualSpokane, 10 September: 23.0 µg/m³, 3.5× usualSpokane, 11 September: 11.3 µg/m³, 1.7× usualSpokane, 12 September: 12.0 µg/m³, 1.8× usualSpokane, 13 September: 14.6 µg/m³, 2.2× usualAbbotsfordAbbotsford, 29 August: 12.7 µg/m³, 2.1× usualAbbotsford, 30 August: 9.7 µg/m³, 1.6× usualAbbotsford, 31 August: 11.6 µg/m³, 1.9× usualAbbotsford, 1 September: 11.1 µg/m³, 1.8× usualAbbotsford, 2 September: 11.9 µg/m³, 2.0× usualAbbotsford, 3 September: 29.7 µg/m³, 5.0× usualAbbotsford, 4 September: 17.3 µg/m³, 2.9× usualAbbotsford, 5 September: 22.2 µg/m³, 3.7× usualAbbotsford, 6 September: 12.0 µg/m³, 2.0× usualAbbotsford, 7 September: 7.1 µg/m³, 1.2× usualAbbotsford, 8 September: 7.9 µg/m³, 1.3× usualAbbotsford, 9 September: 10.0 µg/m³, 1.7× usualAbbotsford, 10 September: 7.8 µg/m³, 1.3× usualAbbotsford, 11 September: 7.8 µg/m³, 1.3× usualAbbotsford, 12 September: 6.1 µg/m³, 1.0× usualAbbotsford, 13 September: 7.9 µg/m³, 1.3× usualInglewood-Finn HillInglewood-Finn Hill, 29 August: 19.1 µg/m³, 3.8× usualInglewood-Finn Hill, 30 August: 13.7 µg/m³, 2.7× usualInglewood-Finn Hill, 31 August: 16.4 µg/m³, 3.3× usualInglewood-Finn Hill, 1 September: 12.3 µg/m³, 2.5× usualInglewood-Finn Hill, 2 September: 16.1 µg/m³, 3.2× usualInglewood-Finn Hill, 3 September: 27.0 µg/m³, 5.4× usualInglewood-Finn Hill, 4 September: 20.9 µg/m³, 4.2× usualInglewood-Finn Hill, 5 September: 37.5 µg/m³, 7.5× usualInglewood-Finn Hill, 6 September: 17.7 µg/m³, 3.5× usualInglewood-Finn Hill, 7 September: 5.1 µg/m³, 1.0× usualInglewood-Finn Hill, 8 September: 7.7 µg/m³, 1.5× usualInglewood-Finn Hill, 9 September: 9.3 µg/m³, 1.9× usualInglewood-Finn Hill, 10 September: 9.7 µg/m³, 1.9× usualInglewood-Finn Hill, 11 September: 13.8 µg/m³, 2.8× usualInglewood-Finn Hill, 12 September: 5.9 µg/m³, 1.2× usualInglewood-Finn Hill, 13 September: 5.3 µg/m³, 1.1× usualSpokane ValleySpokane Valley, 29 August: 10.2 µg/m³, 1.7× usualSpokane Valley, 30 August: 14.6 µg/m³, 2.5× usualSpokane Valley, 31 August: 17.0 µg/m³, 2.9× usualSpokane Valley, 1 September: 14.0 µg/m³, 2.4× usualSpokane Valley, 2 September: 16.4 µg/m³, 2.8× usualSpokane Valley, 3 September: 26.6 µg/m³, 4.5× usualSpokane Valley, 4 September: 29.5 µg/m³, 5.0× usualSpokane Valley, 5 September: 37.2 µg/m³, 6.3× usualSpokane Valley, 6 September: 39.0 µg/m³, 6.6× usualSpokane Valley, 7 September: 18.0 µg/m³, 3.1× usualSpokane Valley, 8 September: 7.6 µg/m³, 1.3× usualSpokane Valley, 9 September: 12.0 µg/m³, 2.0× usualSpokane Valley, 10 September: 20.8 µg/m³, 3.5× usualSpokane Valley, 11 September: 11.5 µg/m³, 1.9× usualSpokane Valley, 12 September: 12.0 µg/m³, 2.0× usualSpokane Valley, 13 September: 14.0 µg/m³, 2.4× usualSunnysideSunnyside, 29 August: 13.5 µg/m³, 2.0× usualSunnyside, 30 August: 13.8 µg/m³, 2.0× usualSunnyside, 31 August: 12.9 µg/m³, 1.9× usualSunnyside, 1 September: 17.8 µg/m³, 2.6× usualSunnyside, 2 September: 18.7 µg/m³, 2.7× usualSunnyside, 3 September: 25.9 µg/m³, 3.8× usualSunnyside, 4 September: no readingSunnyside, 5 September: no readingSunnyside, 6 September: 39.8 µg/m³, 5.8× usualSunnyside, 7 September: 18.2 µg/m³, 2.6× usualSunnyside, 8 September: 12.5 µg/m³, 1.8× usualSunnyside, 9 September: 7.3 µg/m³, 1.1× usualSunnyside, 10 September: 14.3 µg/m³, 2.1× usualSunnyside, 11 September: 16.0 µg/m³, 2.3× usualSunnyside, 12 September: 15.0 µg/m³, 2.2× usualSunnyside, 13 September: 11.6 µg/m³, 1.7× usualKirklandKirkland, 29 August: 18.0 µg/m³, 3.6× usualKirkland, 30 August: 12.5 µg/m³, 2.5× usualKirkland, 31 August: 15.0 µg/m³, 3.0× usualKirkland, 1 September: 12.4 µg/m³, 2.5× usualKirkland, 2 September: 14.7 µg/m³, 2.9× usualKirkland, 3 September: 25.4 µg/m³, 5.1× usualKirkland, 4 September: 20.0 µg/m³, 4.0× usualKirkland, 5 September: 38.8 µg/m³, 7.8× usualKirkland, 6 September: 16.1 µg/m³, 3.2× usualKirkland, 7 September: 4.4 µg/m³, 0.9× usualKirkland, 8 September: 6.5 µg/m³, 1.3× usualKirkland, 9 September: 8.2 µg/m³, 1.6× usualKirkland, 10 September: 9.1 µg/m³, 1.8× usualKirkland, 11 September: 12.6 µg/m³, 2.5× usualKirkland, 12 September: 5.3 µg/m³, 1.1× usualKirkland, 13 September: 4.4 µg/m³, 0.9× usualHelenaHelena, 29 August: no readingHelena, 30 August: no readingHelena, 31 August: no readingHelena, 1 September: no readingHelena, 2 September: no readingHelena, 3 September: 25.3 µg/m³, 3.3× usualHelena, 4 September: 27.9 µg/m³, 3.6× usualHelena, 5 September: 23.2 µg/m³, 3.0× usualHelena, 6 September: 21.2 µg/m³, 2.8× usualHelena, 7 September: 29.8 µg/m³, 3.9× usualHelena, 8 September: 6.7 µg/m³, 0.9× usualHelena, 9 September: 10.2 µg/m³, 1.3× usualHelena, 10 September: 6.5 µg/m³, 0.8× usualHelena, 11 September: 7.5 µg/m³, 1.0× usualHelena, 12 September: 4.3 µg/m³, 0.6× usualHelena, 13 September: 3.6 µg/m³, 0.5× usualYakimaYakima, 29 August: 12.3 µg/m³, 1.9× usualYakima, 30 August: 9.8 µg/m³, 1.5× usualYakima, 31 August: 9.2 µg/m³, 1.4× usualYakima, 1 September: 18.0 µg/m³, 2.8× usualYakima, 2 September: 20.1 µg/m³, 3.1× usualYakima, 3 September: 20.7 µg/m³, 3.2× usualYakima, 4 September: 58.0 µg/m³, 9.1× usualYakima, 5 September: 44.7 µg/m³, 7.0× usualYakima, 6 September: 37.7 µg/m³, 5.9× usualYakima, 7 September: 21.3 µg/m³, 3.3× usualYakima, 8 September: 10.3 µg/m³, 1.6× usualYakima, 9 September: 9.5 µg/m³, 1.5× usualYakima, 10 September: 10.9 µg/m³, 1.7× usualYakima, 11 September: 18.6 µg/m³, 2.9× usualYakima, 12 September: 15.0 µg/m³, 2.3× usualYakima, 13 September: 15.3 µg/m³, 2.4× usualAirdrieAirdrie, 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× usualAirdrie, 5 September: no readingAirdrie, 6 September: no readingAirdrie, 7 September: no readingAirdrie, 8 September: no readingAirdrie, 9 September: no readingAirdrie, 10 September: no readingAirdrie, 11 September: no readingAirdrie, 12 September: no readingAirdrie, 13 September: no readingWenatcheeWenatchee, 29 August: 11.4 µg/m³, 2.2× usualWenatchee, 30 August: 10.6 µg/m³, 2.0× usualWenatchee, 31 August: 10.9 µg/m³, 2.1× usualWenatchee, 1 September: 16.8 µg/m³, 3.2× usualWenatchee, 2 September: 21.5 µg/m³, 4.1× usualWenatchee, 3 September: 20.3 µg/m³, 3.9× usualWenatchee, 4 September: 36.2 µg/m³, 7.0× usualWenatchee, 5 September: 58.2 µg/m³, 11× usualWenatchee, 6 September: 83.3 µg/m³, 16× usualWenatchee, 7 September: 20.4 µg/m³, 3.9× usualWenatchee, 8 September: 22.1 µg/m³, 4.3× usualWenatchee, 9 September: 21.6 µg/m³, 4.2× usualWenatchee, 10 September: 17.0 µg/m³, 3.3× usualWenatchee, 11 September: 18.1 µg/m³, 3.5× usualWenatchee, 12 September: 13.9 µg/m³, 2.7× usualWenatchee, 13 September: 19.2 µg/m³, 3.7× usualKamloopsKamloops, 29 August: 9.4 µg/m³, 1.1× usualKamloops, 30 August: 10.7 µg/m³, 1.2× usualKamloops, 31 August: 11.4 µg/m³, 1.3× usualKamloops, 1 September: 9.8 µg/m³, 1.1× usualKamloops, 2 September: 15.4 µg/m³, 1.8× usualKamloops, 3 September: 18.6 µg/m³, 2.1× usualKamloops, 4 September: 33.3 µg/m³, 3.8× usualKamloops, 5 September: 29.2 µg/m³, 3.3× usualKamloops, 6 September: 33.4 µg/m³, 3.8× usualKamloops, 7 September: 33.9 µg/m³, 3.9× usualKamloops, 8 September: 13.6 µg/m³, 1.5× usualKamloops, 9 September: 12.2 µg/m³, 1.4× usualKamloops, 10 September: 8.5 µg/m³, 1.0× usualKamloops, 11 September: 18.3 µg/m³, 2.1× usualKamloops, 12 September: 19.6 µg/m³, 2.2× usualKamloops, 13 September: 9.5 µg/m³, 1.1× usualCoeur d'AleneCoeur d'Alene, 29 August: 10.5 µg/m³, 1.5× usualCoeur d'Alene, 30 August: 13.9 µg/m³, 2.0× usualCoeur d'Alene, 31 August: 19.0 µg/m³, 2.7× usualCoeur d'Alene, 1 September: 14.8 µg/m³, 2.1× usualCoeur d'Alene, 2 September: 15.1 µg/m³, 2.2× usualCoeur d'Alene, 3 September: 24.8 µg/m³, 3.5× usualCoeur d'Alene, 4 September: 29.8 µg/m³, 4.3× usualCoeur d'Alene, 5 September: 37.7 µg/m³, 5.4× usualCoeur d'Alene, 6 September: 36.8 µg/m³, 5.3× usualCoeur d'Alene, 7 September: 15.7 µg/m³, 2.2× usualCoeur d'Alene, 8 September: 10.8 µg/m³, 1.5× usualCoeur d'Alene, 9 September: 18.9 µg/m³, 2.7× usualCoeur d'Alene, 10 September: 19.3 µg/m³, 2.8× usualCoeur d'Alene, 11 September: 15.2 µg/m³, 2.2× usualCoeur d'Alene, 12 September: 14.5 µg/m³, 2.1× usualCoeur d'Alene, 13 September: 15.7 µg/m³, 2.2× usualMissoulaMissoula, 29 August: 9.0 µg/m³, 1.7× usualMissoula, 30 August: 9.0 µg/m³, 1.7× usualMissoula, 31 August: 17.7 µg/m³, 3.3× usualMissoula, 1 September: 10.3 µg/m³, 1.9× usualMissoula, 2 September: 11.8 µg/m³, 2.2× usualMissoula, 3 September: 16.2 µg/m³, 3.1× usualMissoula, 4 September: 27.6 µg/m³, 5.2× usualMissoula, 5 September: 24.8 µg/m³, 4.7× usualMissoula, 6 September: 33.4 µg/m³, 6.3× usualMissoula, 7 September: 29.6 µg/m³, 5.6× usualMissoula, 8 September: 5.9 µg/m³, 1.1× usualMissoula, 9 September: 9.9 µg/m³, 1.9× usualMissoula, 10 September: 8.2 µg/m³, 1.5× usualMissoula, 11 September: 2.9 µg/m³, 0.5× usualMissoula, 12 September: 3.9 µg/m³, 0.7× usualMissoula, 13 September: 4.6 µg/m³, 0.9× usualVernonVernon, 29 August: 12.8 µg/m³, 1.5× usualVernon, 30 August: 7.0 µg/m³, 0.8× usualVernon, 31 August: 7.3 µg/m³, 0.9× usualVernon, 1 September: 12.7 µg/m³, 1.5× usualVernon, 2 September: 15.0 µg/m³, 1.8× usualVernon, 3 September: 18.8 µg/m³, 2.3× usualVernon, 4 September: 27.5 µg/m³, 3.3× usualVernon, 5 September: 42.4 µg/m³, 5.1× usualVernon, 6 September: 38.4 µg/m³, 4.6× usualVernon, 7 September: 33.1 µg/m³, 4.0× usualVernon, 8 September: 11.8 µg/m³, 1.4× usualVernon, 9 September: 11.2 µg/m³, 1.3× usualVernon, 10 September: 12.0 µg/m³, 1.4× usualVernon, 11 September: 17.8 µg/m³, 2.1× usualVernon, 12 September: 16.3 µg/m³, 2.0× usualVernon, 13 September: 16.8 µg/m³, 2.0× usualBozemanBozeman, 29 August: 8.7 µg/m³, 1.5× usualBozeman, 30 August: 8.0 µg/m³, 1.4× usualBozeman, 31 August: 9.9 µg/m³, 1.7× usualBozeman, 1 September: 11.0 µg/m³, 1.9× usualBozeman, 2 September: 12.1 µg/m³, 2.1× usualBozeman, 3 September: 15.3 µg/m³, 2.6× usualBozeman, 4 September: 26.2 µg/m³, 4.5× usualBozeman, 5 September: 15.8 µg/m³, 2.7× usualBozeman, 6 September: 22.1 µg/m³, 3.8× usualBozeman, 7 September: 18.7 µg/m³, 3.2× usualBozeman, 8 September: 7.2 µg/m³, 1.2× usualBozeman, 9 September: 9.8 µg/m³, 1.7× usualBozeman, 10 September: 7.7 µg/m³, 1.3× usualBozeman, 11 September: 7.6 µg/m³, 1.3× usualBozeman, 12 September: 5.0 µg/m³, 0.9× usualBozeman, 13 September: 5.2 µg/m³, 0.9× usualCranbrookCranbrook, 29 August: 11.9 µg/m³, 1.9× usualCranbrook, 30 August: 9.9 µg/m³, 1.5× usualCranbrook, 31 August: 14.3 µg/m³, 2.2× usualCranbrook, 1 September: 14.9 µg/m³, 2.3× usualCranbrook, 2 September: 15.1 µg/m³, 2.4× usualCranbrook, 3 September: 16.3 µg/m³, 2.5× usualCranbrook, 4 September: 25.4 µg/m³, 4.0× usualCranbrook, 5 September: 25.5 µg/m³, 4.0× usualCranbrook, 6 September: 39.3 µg/m³, 6.1× usualCranbrook, 7 September: 56.2 µg/m³, 8.8× usualCranbrook, 8 September: 30.0 µg/m³, 4.7× usualCranbrook, 9 September: 18.6 µg/m³, 2.9× usualCranbrook, 10 September: 12.2 µg/m³, 1.9× usualCranbrook, 11 September: 12.5 µg/m³, 2.0× usualCranbrook, 12 September: 14.8 µg/m³, 2.3× usualCranbrook, 13 September: 14.8 µg/m³, 2.3× usualKelownaKelowna, 29 August: 9.2 µg/m³, 1.2× usualKelowna, 30 August: 6.9 µg/m³, 0.9× usualKelowna, 31 August: 9.4 µg/m³, 1.2× usualKelowna, 1 September: 13.0 µg/m³, 1.6× usualKelowna, 2 September: 16.8 µg/m³, 2.1× usualKelowna, 3 September: 17.1 µg/m³, 2.2× usualKelowna, 4 September: 23.2 µg/m³, 2.9× usualKelowna, 5 September: 42.7 µg/m³, 5.4× usualKelowna, 6 September: 35.0 µg/m³, 4.4× usualKelowna, 7 September: 37.7 µg/m³, 4.8× usualKelowna, 8 September: 13.6 µg/m³, 1.7× usualKelowna, 9 September: 13.3 µg/m³, 1.7× usualKelowna, 10 September: 14.8 µg/m³, 1.9× usualKelowna, 11 September: 16.1 µg/m³, 2.0× usualKelowna, 12 September: 13.5 µg/m³, 1.7× usualKelowna, 13 September: 14.9 µg/m³, 1.9× usualEllensburgEllensburg, 29 August: 11.3 µg/m³, 2.2× usualEllensburg, 30 August: 9.3 µg/m³, 1.8× usualEllensburg, 31 August: 8.5 µg/m³, 1.6× usualEllensburg, 1 September: 11.1 µg/m³, 2.1× usualEllensburg, 2 September: 11.5 µg/m³, 2.2× usualEllensburg, 3 September: 14.8 µg/m³, 2.8× usualEllensburg, 4 September: 23.7 µg/m³, 4.6× usualEllensburg, 5 September: 40.1 µg/m³, 7.7× usualEllensburg, 6 September: 41.3 µg/m³, 7.9× usualEllensburg, 7 September: 7.3 µg/m³, 1.4× usualEllensburg, 8 September: 7.7 µg/m³, 1.5× usualEllensburg, 9 September: 6.2 µg/m³, 1.2× usualEllensburg, 10 September: 11.2 µg/m³, 2.2× usualEllensburg, 11 September: 13.0 µg/m³, 2.5× usualEllensburg, 12 September: 7.3 µg/m³, 1.4× usualEllensburg, 13 September: 7.3 µg/m³, 1.4× usualLewistonLewiston, 29 August: 14.1 µg/m³, 1.6× usualLewiston, 30 August: 14.7 µg/m³, 1.7× usualLewiston, 31 August: 18.3 µg/m³, 2.1× usualLewiston, 1 September: 13.8 µg/m³, 1.6× usualLewiston, 2 September: 15.1 µg/m³, 1.8× usualLewiston, 3 September: 14.8 µg/m³, 1.7× usualLewiston, 4 September: 17.7 µg/m³, 2.1× usualLewiston, 5 September: 35.1 µg/m³, 4.1× usualLewiston, 6 September: 34.8 µg/m³, 4.0× usualLewiston, 7 September: 11.8 µg/m³, 1.4× usualLewiston, 8 September: 9.6 µg/m³, 1.1× usualLewiston, 9 September: 13.1 µg/m³, 1.5× usualLewiston, 10 September: 18.4 µg/m³, 2.1× usualLewiston, 11 September: 9.2 µg/m³, 1.1× usualLewiston, 12 September: 9.2 µg/m³, 1.1× usualLewiston, 13 September: 12.3 µg/m³, 1.4× usualTri-CitiesTri-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/m³, 4.0× usualTri-Cities, 4 September: 19.8 µg/m³, 4.0× usualTri-Cities, 5 September: 34.8 µg/m³, 7.0× usualTri-Cities, 6 September: 40.2 µg/m³, 8.0× usualTri-Cities, 7 September: 15.1 µg/m³, 3.0× usualTri-Cities, 8 September: 8.4 µg/m³, 1.7× usualTri-Cities, 9 September: 6.0 µg/m³, 1.2× usualTri-Cities, 10 September: 10.2 µg/m³, 2.0× usualTri-Cities, 11 September: 11.5 µg/m³, 2.3× usualTri-Cities, 12 September: 9.9 µg/m³, 2.0× usualTri-Cities, 13 September: 10.8 µg/m³, 2.2× usualMoscowMoscow, 29 August: 12.1 µg/m³, 1.7× usualMoscow, 30 August: 15.0 µg/m³, 2.1× usualMoscow, 31 August: 17.4 µg/m³, 2.4× usualMoscow, 1 September: 13.7 µg/m³, 1.9× usualMoscow, 2 September: 18.5 µg/m³, 2.5× usualMoscow, 3 September: 18.1 µg/m³, 2.5× usualMoscow, 4 September: 18.8 µg/m³, 2.6× usualMoscow, 5 September: 34.5 µg/m³, 4.7× usualMoscow, 6 September: 29.1 µg/m³, 4.0× usualMoscow, 7 September: 12.2 µg/m³, 1.7× usualMoscow, 8 September: 11.0 µg/m³, 1.5× usualMoscow, 9 September: 15.3 µg/m³, 2.1× usualMoscow, 10 September: 16.5 µg/m³, 2.3× usualMoscow, 11 September: 10.5 µg/m³, 1.4× usualMoscow, 12 September: 8.5 µg/m³, 1.2× usualMoscow, 13 September: 14.6 µg/m³, 2.0× usualPullmanPullman, 29 August: 12.2 µg/m³, 2.0× usualPullman, 30 August: 14.2 µg/m³, 2.3× usualPullman, 31 August: 17.1 µg/m³, 2.8× usualPullman, 1 September: 13.2 µg/m³, 2.2× usualPullman, 2 September: 17.3 µg/m³, 2.8× usualPullman, 3 September: 14.7 µg/m³, 2.4× usualPullman, 4 September: 15.8 µg/m³, 2.6× usualPullman, 5 September: 34.2 µg/m³, 5.6× usualPullman, 6 September: 31.4 µg/m³, 5.1× usualPullman, 7 September: 11.2 µg/m³, 1.8× usualPullman, 8 September: 9.4 µg/m³, 1.5× usualPullman, 9 September: 10.4 µg/m³, 1.7× usualPullman, 10 September: 14.3 µg/m³, 2.3× usualPullman, 11 September: 8.3 µg/m³, 1.4× usualPullman, 12 September: 8.7 µg/m³, 1.4× usualPullman, 13 September: 13.6 µg/m³, 2.2× usualShorelineShoreline, 29 August: 12.6 µg/m³, 2.3× usualShoreline, 30 August: 10.0 µg/m³, 1.8× usualShoreline, 31 August: 10.9 µg/m³, 1.9× usualShoreline, 1 September: 10.3 µg/m³, 1.8× usualShoreline, 2 September: 10.2 µg/m³, 1.8× usualShoreline, 3 September: 16.6 µg/m³, 3.0× usualShoreline, 4 September: 12.2 µg/m³, 2.2× usualShoreline, 5 September: 33.7 µg/m³, 6.0× usualShoreline, 6 September: 11.4 µg/m³, 2.0× usualShoreline, 7 September: 5.9 µg/m³, 1.1× usualShoreline, 8 September: 6.6 µg/m³, 1.2× usualShoreline, 9 September: 8.1 µg/m³, 1.4× usualShoreline, 10 September: 7.9 µg/m³, 1.4× usualShoreline, 11 September: 10.3 µg/m³, 1.8× usualShoreline, 12 September: 6.7 µg/m³, 1.2× usualShoreline, 13 September: 5.7 µg/m³, 1.0× usualHermistonHermiston, 29 August: 20.5 µg/m³, 3.4× usualHermiston, 30 August: 14.0 µg/m³, 2.3× usualHermiston, 31 August: 12.9 µg/m³, 2.2× usualHermiston, 1 September: 13.2 µg/m³, 2.2× usualHermiston, 2 September: 16.3 µg/m³, 2.7× usualHermiston, 3 September: 18.0 µg/m³, 3.0× usualHermiston, 4 September: 18.5 µg/m³, 3.1× usualHermiston, 5 September: 31.4 µg/m³, 5.2× usualHermiston, 6 September: 29.3 µg/m³, 4.9× usualHermiston, 7 September: 14.7 µg/m³, 2.4× usualHermiston, 8 September: 8.0 µg/m³, 1.3× usualHermiston, 9 September: 6.1 µg/m³, 1.0× usualHermiston, 10 September: 9.7 µg/m³, 1.6× usualHermiston, 11 September: 15.2 µg/m³, 2.5× usualHermiston, 12 September: 12.3 µg/m³, 2.1× usualHermiston, 13 September: 14.1 µg/m³, 2.4× usualNampaNampa, 29 August: 10.3 µg/m³, 1.5× usualNampa, 30 August: 11.8 µg/m³, 1.7× usualNampa, 31 August: 9.5 µg/m³, 1.3× usualNampa, 1 September: 12.3 µg/m³, 1.7× usualNampa, 2 September: 10.9 µg/m³, 1.5× usualNampa, 3 September: 12.7 µg/m³, 1.8× usualNampa, 4 September: 17.7 µg/m³, 2.5× usualNampa, 5 September: 30.5 µg/m³, 4.3× usualNampa, 6 September: 16.3 µg/m³, 2.3× usualNampa, 7 September: 9.9 µg/m³, 1.4× usualNampa, 8 September: 8.8 µg/m³, 1.2× usualNampa, 9 September: 9.9 µg/m³, 1.4× usualNampa, 10 September: 10.6 µg/m³, 1.5× usualNampa, 11 September: 5.5 µg/m³, 0.8× usualNampa, 12 September: 5.3 µg/m³, 0.7× usualNampa, 13 September: 9.8 µg/m³, 1.4× usualMeridianMeridian, 29 August: 10.8 µg/m³, 1.7× usualMeridian, 30 August: 10.9 µg/m³, 1.8× usualMeridian, 31 August: 9.8 µg/m³, 1.6× usualMeridian, 1 September: 12.4 µg/m³, 2.0× usualMeridian, 2 September: 9.3 µg/m³, 1.5× usualMeridian, 3 September: 10.6 µg/m³, 1.7× usualMeridian, 4 September: 17.0 µg/m³, 2.7× usualMeridian, 5 September: 30.1 µg/m³, 4.9× usualMeridian, 6 September: 17.8 µg/m³, 2.9× usualMeridian, 7 September: 10.4 µg/m³, 1.7× usualMeridian, 8 September: 6.0 µg/m³, 1.0× usualMeridian, 9 September: 6.3 µg/m³, 1.0× usualMeridian, 10 September: no readingMeridian, 11 September: no readingMeridian, 12 September: no readingMeridian, 13 September: no readingBoiseBoise, 29 August: 10.3 µg/m³, 1.9× usualBoise, 30 August: 10.9 µg/m³, 2.0× usualBoise, 31 August: 9.5 µg/m³, 1.8× usualBoise, 1 September: 10.6 µg/m³, 2.0× usualBoise, 2 September: 10.5 µg/m³, 1.9× usualBoise, 3 September: 9.6 µg/m³, 1.8× usualBoise, 4 September: 14.5 µg/m³, 2.7× usualBoise, 5 September: 29.8 µg/m³, 5.5× usualBoise, 6 September: 19.0 µg/m³, 3.5× usualBoise, 7 September: 10.4 µg/m³, 1.9× usualBoise, 8 September: 6.5 µg/m³, 1.2× usualBoise, 9 September: 6.1 µg/m³, 1.1× usualBoise, 10 September: 9.6 µg/m³, 1.8× usualBoise, 11 September: 4.8 µg/m³, 0.9× usualBoise, 12 September: 4.9 µg/m³, 0.9× usualBoise, 13 September: 6.2 µg/m³, 1.1× usualRexburgRexburg, 29 August: 9.5 µg/m³, 1.4× usualRexburg, 30 August: 9.0 µg/m³, 1.3× usualRexburg, 31 August: 9.2 µg/m³, 1.3× usualRexburg, 1 September: 10.5 µg/m³, 1.5× usualRexburg, 2 September: 8.3 µg/m³, 1.2× usualRexburg, 3 September: 10.2 µg/m³, 1.5× usualRexburg, 4 September: 14.6 µg/m³, 2.1× usualRexburg, 5 September: 29.7 µg/m³, 4.2× usualRexburg, 6 September: 21.7 µg/m³, 3.1× usualRexburg, 7 September: 9.7 µg/m³, 1.4× usualRexburg, 8 September: 6.3 µg/m³, 0.9× usualRexburg, 9 September: 7.7 µg/m³, 1.1× usualRexburg, 10 September: 5.8 µg/m³, 0.8× usualRexburg, 11 September: 6.4 µg/m³, 0.9× usualRexburg, 12 September: 5.8 µg/m³, 0.8× usualRexburg, 13 September: 5.8 µg/m³, 0.8× usualIdaho FallsIdaho Falls, 29 August: 11.9 µg/m³, 2.4× usualIdaho Falls, 30 August: 9.8 µg/m³, 2.0× usualIdaho Falls, 31 August: 11.3 µg/m³, 2.3× usualIdaho Falls, 1 September: 10.7 µg/m³, 2.1× usualIdaho Falls, 2 September: 9.1 µg/m³, 1.8× usualIdaho Falls, 3 September: 11.4 µg/m³, 2.3× usualIdaho Falls, 4 September: 12.4 µg/m³, 2.5× usualIdaho Falls, 5 September: 29.3 µg/m³, 5.9× usualIdaho Falls, 6 September: 24.7 µg/m³, 4.9× usualIdaho Falls, 7 September: 6.7 µg/m³, 1.3× usualIdaho Falls, 8 September: 5.9 µg/m³, 1.2× usualIdaho Falls, 9 September: 5.9 µg/m³, 1.2× usualIdaho Falls, 10 September: 3.3 µg/m³, 0.7× usualIdaho Falls, 11 September: 4.4 µg/m³, 0.9× usualIdaho Falls, 12 September: 4.2 µg/m³, 0.8× usualIdaho Falls, 13 September: 3.5 µg/m³, 0.7× usualWalla WallaWalla Walla, 29 August: 12.9 µg/m³, 2.2× usualWalla Walla, 30 August: 12.5 µg/m³, 2.1× usualWalla Walla, 31 August: 11.7 µg/m³, 2.0× usualWalla Walla, 1 September: 12.4 µg/m³, 2.1× usualWalla Walla, 2 September: 13.0 µg/m³, 2.2× usualWalla Walla, 3 September: 14.0 µg/m³, 2.4× usualWalla Walla, 4 September: 15.7 µg/m³, 2.7× usualWalla Walla, 5 September: 27.1 µg/m³, 4.6× usualWalla Walla, 6 September: 26.3 µg/m³, 4.5× usualWalla Walla, 7 September: 11.6 µg/m³, 2.0× usualWalla Walla, 8 September: 6.6 µg/m³, 1.1× usualWalla Walla, 9 September: 7.0 µg/m³, 1.2× usualWalla Walla, 10 September: 10.1 µg/m³, 1.7× usualWalla Walla, 11 September: 10.3 µg/m³, 1.7× usualWalla Walla, 12 September: 10.4 µg/m³, 1.8× usualWalla Walla, 13 September: 12.0 µg/m³, 2.0× usualButteButte, 29 August: 8.5 µg/m³, 1.6× usualButte, 30 August: 9.9 µg/m³, 1.9× usualButte, 31 August: 13.2 µg/m³, 2.5× usualButte, 1 September: 10.8 µg/m³, 2.1× usualButte, 2 September: 11.2 µg/m³, 2.2× usualButte, 3 September: 21.0 µg/m³, 4.0× usualButte, 4 September: 24.3 µg/m³, 4.7× usualButte, 5 September: 22.2 µg/m³, 4.3× usualButte, 6 September: 31.9 µg/m³, 6.1× usualButte, 7 September: 30.2 µg/m³, 5.8× usualButte, 8 September: 6.8 µg/m³, 1.3× usualButte, 9 September: 10.5 µg/m³, 2.0× usualButte, 10 September: 6.3 µg/m³, 1.2× usualButte, 11 September: 5.4 µg/m³, 1.0× usualButte, 12 September: 3.2 µg/m³, 0.6× usualButte, 13 September: 4.1 µg/m³, 0.8× usual29 Aug311 Sep24681012
Every counted city, in the order the episode reached them, 3 days before to 3 after. Each square is a day, coloured by that day's PM2.5; outlined: at twice the city's usual or more.
Good0–50
Moderate51–100
Sensitive groups101–150
Unhealthy151–200
Very unhealthy201–300
Hazardous301+

Every city it reached

CityDaysHighestUsualAbove usual
SquamishBritish Columbia, Canada4 173.03 September7.025×
West VancouverBritish Columbia, Canada3 87.23 September5.217×
WenatcheeWashington, United States3 83.36 September5.216×
Sherwood ParkAlberta, Canada8 126.01 September8.016×
St. AlbertAlberta, Canada7 126.01 September8.215×
EdmontonAlberta, Canada8 140.01 September11.412×
CalgaryAlberta, Canada9 100.32 September10.19.9×
LethbridgeAlberta, Canada6 72.82 September7.99.2×
YakimaWashington, United States3 58.04 September6.49.1×
CranbrookBritish Columbia, Canada5 56.27 September6.48.8×
Tri-CitiesWashington, United States2 40.26 September4.78.0×
EllensburgWashington, United States2 41.36 September5.27.9×
KirklandWashington, United States2 38.85 September3.57.8×
Inglewood-Finn HillWashington, United States2 37.55 September4.17.5×
CoquitlamBritish Columbia, Canada1 40.13 September5.47.4×
BurnabyBritish Columbia, Canada1 37.53 September5.46.9×
North VancouverBritish Columbia, Canada1 35.13 September5.16.9×
Medicine HatAlberta, Canada3 48.02 September7.26.7×
Spokane ValleyWashington, United States4 39.06 September5.96.6×
SpokaneWashington, United States4 43.56 September6.66.6×
Swift CurrentSaskatchewan, Canada2 53.42 September8.26.5×
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×
MissoulaMontana, United States3 33.46 September5.36.3×
Red DeerAlberta, Canada7 58.62 September9.46.2×
ButteMontana, United States2 31.96 September5.26.1×
Port CoquitlamBritish Columbia, Canada1 31.03 September5.16.1×
ShorelineWashington, United States1 33.75 September5.66.0×
Idaho FallsIdaho, United States1 29.35 September4.55.9×
SunnysideWashington, United States2 39.86 September6.95.8×
PullmanWashington, United States2 34.25 September6.15.6×
BoiseIdaho, United States1 29.85 September5.45.5×
KelownaBritish Columbia, Canada3 42.75 September7.95.4×
Coeur d'AleneIdaho, United States3 37.75 September7.05.4×
AirdrieAlberta, Canada1 41.94 September7.95.3×
SaskatoonSaskatchewan, Canada1 55.31 September10.55.3×
HermistonOregon, United States2 31.45 September6.05.2×
VernonBritish Columbia, Canada4 42.45 September8.35.1×
AbbotsfordBritish Columbia, Canada1 29.73 September6.05.0×
MeridianIdaho, United States1 30.15 September6.24.9×
Moses LakeWashington, United States2 31.92 September6.74.8×
ChilliwackBritish Columbia, Canada3 31.33 September6.64.7×
MoscowIdaho, United States2 34.55 September7.34.7×
BillingsMontana, United States2 31.13 September6.74.6×
Walla WallaWashington, United States2 27.15 September5.94.6×
BozemanMontana, United States1 26.24 September5.84.5×
NampaIdaho, United States1 30.55 September7.14.3×
RexburgIdaho, United States1 29.75 September7.04.2×
LewistonIdaho, United States2 35.15 September8.64.1×
HelenaMontana, United States3 29.87 September7.73.9×
KamloopsBritish Columbia, Canada4 33.97 September8.83.9×
ReginaSaskatchewan, Canada1 33.92 September10.23.3×
Great FallsMontana, United States3 33.03 September11.62.8×

Daily means in µg/m³. Usual: the city's median for this time of year (its days within 21 days of the date, every year, leaving out the week around it). Above usual: its highest day against that.

Against other episodes in the United States and Canada

Number 18 of 106 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 106.

Use this page

SmogRank, North-western United States and Canada, September 2025: 54 cities with PM2.5 at twice their usual or more, 1 to 10 September 2025, smogrank.com/episodes/2025-09-north-western-united-states-and-canada (accessed 2 October 2026).

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You're welcome to reuse a single chart, image or figure with this citation and a link. Terms.

An episode is a run of days when many cities close to each other (four or more within 350 km on a day, 8 or more in all) each had a daily PM2.5 mean of at least 25 µg/m³ and at least 2 times their usual for that time of year. Found in our own measurements, not picked by hand. How we find episodes. Values are each city's daily mean of its own monitors; causes are the usual kinds for a pattern like this, not a confirmed source.