SmogRank / Episodes / United States

North-western United States and Canada, 4 to 11 August 2026

For 8 days, from 4 to 11 August 2026, 99 cities in the United States and Canada had PM2.5 at least twice their usual for the time of year. The worst reading was Wenatchee, Washington, United States: 204.0 µg/m³ on 4 August, about 41× its usual 5.0.

No cause namedWe have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached99in 2 countries
Days84 to 11 August 2026
Worst day5 August81 cities counted
Furthest above usual41×Wenatchee

Day by day

5 August 81 cities at twice their usual or more
KennewickLethbridgeLoganNorth OgdenBountifulMagnaMedicine HatSalt Lake CityWest Valley CityHerrimanHighlandOremSpanish ForkMonroeRedmondRock SpringsMount VernonAnacortesDeltaSwift CurrentPort AngelesVictoriaRichmondVancouverCentral SaanichLangfordAberdeenParadiseReddingDuncanNorth CowichanChicoCasperNanaimoHarewoodCoos BaySaskatoonLaramieCampbell RiverCheyenneFort CollinsReginaBoulderLongmontWindsorGoldenArvadaGreeleyWestminsterNorthglennLakewoodThorntonDenverBrightonCalgaryAirdrieMillcreekGreat FallsWest JordanTooeleBrigham CityGilletteMedfordAshlandHelenaIdaho FallsAltamontMoscowPocatelloBellinghamLewistonSeattlePort AlberniSquamishSheridanMarysvilleColumbia CityStrawberry HillBillingsRoseburgBremertonPicnic Point-North LynnwoodBurnabyRedmondLaceyShorelineGrants PassMissoulaWest VancouverPullmanBendLangleyLongviewMeridianBurienPort CoquitlamNorth VancouverTacomaRentonCoeur d'AleneForest GroveBoiseBellevueAuburnNampaKentMilwaukieBozemanSpokaneButteKelownaParklandCoquitlamTwin FallsCentraliaHermistonSpokane ValleySalmon CreekVancouverInglewood-Finn HillAbbotsfordSunnysideHillsboroBothellCranbrookPortlandMcMinnvillePendletonTigardKirklandTri-CitiesWoodburnMoses LakeDallasBeavertonSalemCorvallisVernonChilliwackNorth CreekUnion Hill-Novelty HillPascoWalla WallaEllensburgGreshamThe DallesAlbanyKamloopsCanbyOregon CityYakimaEugeneWenatchee
1 Aug234567891011121314
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

WenatcheeWenatchee, 1 August: 4.9 µg/m³Wenatchee, 2 August: 3.0 µg/m³Wenatchee, 3 August: 79.7 µg/m³Wenatchee, 4 August: 204.0 µg/m³, 41× its usual 5.0Wenatchee, 5 August: 146.0 µg/m³, 29× its usual 5.0Wenatchee, 6 August: 146.0 µg/m³, 29× its usual 5.1Wenatchee, 7 August: 99.9 µg/m³, 20× its usual 5.1Wenatchee, 8 August: 8.6 µg/m³Wenatchee, 9 August: 14.0 µg/m³Wenatchee, 10 August: 5.2 µg/m³Wenatchee, 11 August: 6.1 µg/m³Wenatchee, 12 August: 38.7 µg/m³Wenatchee, 13 August: 57.5 µg/m³Wenatchee, 14 August: 35.2 µg/m³KamloopsKamloops, 1 August: 79.2 µg/m³Kamloops, 2 August: 25.3 µg/m³Kamloops, 3 August: 6.1 µg/m³Kamloops, 4 August: 31.8 µg/m³, 2.9× its usual 11.0Kamloops, 5 August: 73.2 µg/m³, 6.7× its usual 11.0Kamloops, 6 August: 146.0 µg/m³, 13× its usual 11.1Kamloops, 7 August: 191.0 µg/m³, 17× its usual 11.2Kamloops, 8 August: 140.0 µg/m³, 13× its usual 11.0Kamloops, 9 August: 167.0 µg/m³, 15× its usual 11.0Kamloops, 10 August: 97.5 µg/m³Kamloops, 11 August: 18.4 µg/m³Kamloops, 12 August: 8.0 µg/m³Kamloops, 13 August: 9.3 µg/m³Kamloops, 14 August: 19.3 µg/m³EugeneEugene, 1 August: 1.8 µg/m³Eugene, 2 August: 3.2 µg/m³Eugene, 3 August: 17.5 µg/m³Eugene, 4 August: 56.4 µg/m³, 11× its usual 4.4Eugene, 5 August: 120.0 µg/m³, 24× its usual 4.4Eugene, 6 August: 85.2 µg/m³, 17× its usual 4.5Eugene, 7 August: 19.5 µg/m³Eugene, 8 August: 9.9 µg/m³Eugene, 9 August: 2.9 µg/m³Eugene, 10 August: 3.3 µg/m³Eugene, 11 August: 3.2 µg/m³Eugene, 12 August: 2.3 µg/m³Eugene, 13 August: 7.6 µg/m³Eugene, 14 August: 5.9 µg/m³Walla WallaWalla Walla, 1 August: 13.4 µg/m³Walla Walla, 2 August: 3.1 µg/m³Walla Walla, 3 August: 32.2 µg/m³Walla Walla, 4 August: 71.3 µg/m³, 10× its usual 7.0Walla Walla, 5 August: 108.0 µg/m³, 15× its usual 7.2Walla Walla, 6 August: 105.0 µg/m³, 15× its usual 7.2Walla Walla, 7 August: 51.0 µg/m³, 7.1× its usual 7.2Walla Walla, 8 August: 18.4 µg/m³Walla Walla, 9 August: 8.0 µg/m³Walla Walla, 10 August: 10.3 µg/m³Walla Walla, 11 August: 11.0 µg/m³Walla Walla, 12 August: 14.0 µg/m³Walla Walla, 13 August: 24.3 µg/m³Walla Walla, 14 August: 20.0 µg/m³YakimaYakima, 1 August: 4.1 µg/m³Yakima, 2 August: 4.3 µg/m³Yakima, 3 August: 47.5 µg/m³Yakima, 4 August: 100.0 µg/m³, 17× its usual 5.8Yakima, 5 August: 91.4 µg/m³, 15× its usual 6.1Yakima, 6 August: 57.1 µg/m³, 9.2× its usual 6.2Yakima, 7 August: 24.6 µg/m³Yakima, 8 August: 10.4 µg/m³Yakima, 9 August: 36.2 µg/m³, 5.9× its usual 6.1Yakima, 10 August: 2.8 µg/m³Yakima, 11 August: 6.3 µg/m³Yakima, 12 August: 25.9 µg/m³Yakima, 13 August: 48.5 µg/m³Yakima, 14 August: 27.1 µg/m³Moses LakeMoses Lake, 1 August: 5.1 µg/m³Moses Lake, 2 August: 34.8 µg/m³Moses Lake, 3 August: 69.6 µg/m³Moses Lake, 4 August: 85.1 µg/m³, 12× its usual 7.2Moses Lake, 5 August: 69.3 µg/m³, 9.5× its usual 7.3Moses Lake, 6 August: 58.1 µg/m³, 7.9× its usual 7.4Moses Lake, 7 August: 40.4 µg/m³, 5.5× its usual 7.4Moses Lake, 8 August: 44.9 µg/m³, 6.0× its usual 7.5Moses Lake, 9 August: 87.1 µg/m³, 12× its usual 7.5Moses Lake, 10 August: 36.3 µg/m³Moses Lake, 11 August: 42.0 µg/m³Moses Lake, 12 August: 36.4 µg/m³Moses Lake, 13 August: 16.5 µg/m³Moses Lake, 14 August: 10.7 µg/m³PendletonPendleton, 1 August: 14.3 µg/m³Pendleton, 2 August: 7.7 µg/m³Pendleton, 3 August: 31.3 µg/m³Pendleton, 4 August: 78.6 µg/m³, 9.9× its usual 7.9Pendleton, 5 August: 86.3 µg/m³, 11× its usual 8.0Pendleton, 6 August: 78.2 µg/m³, 9.8× its usual 8.0Pendleton, 7 August: 48.1 µg/m³, 6.0× its usual 8.0Pendleton, 8 August: 31.4 µg/m³, 3.9× its usual 8.0Pendleton, 9 August: 14.6 µg/m³Pendleton, 10 August: 14.8 µg/m³Pendleton, 11 August: 15.8 µg/m³Pendleton, 12 August: 12.2 µg/m³Pendleton, 13 August: 20.9 µg/m³Pendleton, 14 August: 21.4 µg/m³Oregon CityOregon City, 1 August: 2.0 µg/m³Oregon City, 2 August: 3.0 µg/m³Oregon City, 3 August: 17.2 µg/m³Oregon City, 4 August: 70.5 µg/m³, 14× its usual 3.4Oregon City, 5 August: 86.2 µg/m³, 17× its usual 3.5Oregon City, 6 August: 52.2 µg/m³, 10× its usual 3.4Oregon City, 7 August: 13.4 µg/m³Oregon City, 8 August: 4.6 µg/m³Oregon City, 9 August: 2.8 µg/m³Oregon City, 10 August: 2.6 µg/m³Oregon City, 11 August: 2.2 µg/m³Oregon City, 12 August: 2.2 µg/m³Oregon City, 13 August: 7.3 µg/m³Oregon City, 14 August: 6.3 µg/m³CanbyCanby, 1 August: 2.2 µg/m³Canby, 2 August: 3.6 µg/m³Canby, 3 August: 17.6 µg/m³Canby, 4 August: 66.1 µg/m³, 13× its usual 4.1Canby, 5 August: 86.1 µg/m³, 17× its usual 4.1Canby, 6 August: 45.7 µg/m³, 9.1× its usual 4.1Canby, 7 August: 17.9 µg/m³Canby, 8 August: 5.9 µg/m³Canby, 9 August: 3.7 µg/m³Canby, 10 August: 3.6 µg/m³Canby, 11 August: 2.8 µg/m³Canby, 12 August: 2.9 µg/m³Canby, 13 August: 11.5 µg/m³Canby, 14 August: 9.3 µg/m³EllensburgEllensburg, 1 August: 4.1 µg/m³Ellensburg, 2 August: 4.3 µg/m³Ellensburg, 3 August: 45.1 µg/m³Ellensburg, 4 August: 84.0 µg/m³, 15× its usual 5.5Ellensburg, 5 August: 83.9 µg/m³, 15× its usual 5.7Ellensburg, 6 August: 43.2 µg/m³, 7.6× its usual 5.7Ellensburg, 7 August: 24.7 µg/m³Ellensburg, 8 August: 12.4 µg/m³Ellensburg, 9 August: 19.5 µg/m³Ellensburg, 10 August: 8.5 µg/m³Ellensburg, 11 August: 8.5 µg/m³Ellensburg, 12 August: 17.9 µg/m³Ellensburg, 13 August: 60.6 µg/m³Ellensburg, 14 August: 46.2 µg/m³The DallesThe Dalles, 1 August: 2.9 µg/m³The Dalles, 2 August: 3.8 µg/m³The Dalles, 3 August: 28.6 µg/m³The Dalles, 4 August: 58.6 µg/m³, 12× its usual 4.9The Dalles, 5 August: 77.3 µg/m³, 15× its usual 5.1The Dalles, 6 August: 83.8 µg/m³, 16× its usual 5.1The Dalles, 7 August: 19.3 µg/m³The Dalles, 8 August: 11.2 µg/m³The Dalles, 9 August: 5.0 µg/m³The Dalles, 10 August: 5.3 µg/m³The Dalles, 11 August: 5.8 µg/m³The Dalles, 12 August: 5.1 µg/m³The Dalles, 13 August: 22.8 µg/m³The Dalles, 14 August: 28.6 µg/m³AlbanyAlbany, 1 August: 2.0 µg/m³Albany, 2 August: 3.3 µg/m³Albany, 3 August: 19.2 µg/m³Albany, 4 August: 58.8 µg/m³, 12× its usual 3.6Albany, 5 August: 83.3 µg/m³, 17× its usual 3.6Albany, 6 August: 55.8 µg/m³, 11× its usual 3.6Albany, 7 August: 14.3 µg/m³Albany, 8 August: 6.5 µg/m³Albany, 9 August: 3.0 µg/m³Albany, 10 August: 3.1 µg/m³Albany, 11 August: 2.6 µg/m³Albany, 12 August: 2.1 µg/m³Albany, 13 August: 6.0 µg/m³Albany, 14 August: 5.6 µg/m³Spokane ValleySpokane Valley, 1 August: 12.3 µg/m³Spokane Valley, 2 August: 58.9 µg/m³Spokane Valley, 3 August: 95.6 µg/m³Spokane Valley, 4 August: 64.5 µg/m³, 7.9× its usual 8.2Spokane Valley, 5 August: 39.2 µg/m³, 4.6× its usual 8.6Spokane Valley, 6 August: 53.4 µg/m³, 5.9× its usual 9.0Spokane Valley, 7 August: 46.5 µg/m³, 5.1× its usual 9.1Spokane Valley, 8 August: 59.8 µg/m³, 6.6× its usual 9.1Spokane Valley, 9 August: 82.8 µg/m³, 9.1× its usual 9.1Spokane Valley, 10 August: 33.8 µg/m³Spokane Valley, 11 August: 27.9 µg/m³Spokane Valley, 12 August: 29.9 µg/m³Spokane Valley, 13 August: 17.8 µg/m³Spokane Valley, 14 August: 8.4 µg/m³ChilliwackChilliwack, 1 August: 2.7 µg/m³Chilliwack, 2 August: 3.0 µg/m³Chilliwack, 3 August: 14.5 µg/m³Chilliwack, 4 August: 52.1 µg/m³, 8.7× its usual 6.0Chilliwack, 5 August: 81.5 µg/m³, 14× its usual 6.0Chilliwack, 6 August: 51.5 µg/m³, 8.6× its usual 6.0Chilliwack, 7 August: 19.9 µg/m³Chilliwack, 8 August: 9.5 µg/m³Chilliwack, 9 August: 5.7 µg/m³Chilliwack, 10 August: 6.0 µg/m³Chilliwack, 11 August: 4.7 µg/m³Chilliwack, 12 August: 6.5 µg/m³Chilliwack, 13 August: 21.9 µg/m³Chilliwack, 14 August: 33.5 µg/m³GreshamGresham, 1 August: 2.6 µg/m³Gresham, 2 August: 3.7 µg/m³Gresham, 3 August: 15.0 µg/m³Gresham, 4 August: 54.4 µg/m³, 11× its usual 3.5Gresham, 5 August: 79.9 µg/m³, 16× its usual 3.5Gresham, 6 August: 37.4 µg/m³, 7.5× its usual 3.5Gresham, 7 August: 12.3 µg/m³Gresham, 8 August: 5.3 µg/m³Gresham, 9 August: 3.6 µg/m³Gresham, 10 August: 3.5 µg/m³Gresham, 11 August: 3.3 µg/m³Gresham, 12 August: 2.6 µg/m³Gresham, 13 August: 8.4 µg/m³Gresham, 14 August: 7.9 µg/m³NampaNampa, 1 August: 39.2 µg/m³Nampa, 2 August: 33.4 µg/m³Nampa, 3 August: 65.3 µg/m³Nampa, 4 August: 66.8 µg/m³, 7.0× its usual 9.5Nampa, 5 August: 38.1 µg/m³, 4.0× its usual 9.6Nampa, 6 August: 45.1 µg/m³, 4.7× its usual 9.6Nampa, 7 August: 77.5 µg/m³, 8.1× its usual 9.6Nampa, 8 August: 70.8 µg/m³, 7.2× its usual 9.8Nampa, 9 August: 35.7 µg/m³, 3.6× its usual 9.8Nampa, 10 August: 34.3 µg/m³, 3.4× its usual 10.0Nampa, 11 August: 39.4 µg/m³, 3.8× its usual 10.3Nampa, 12 August: 24.3 µg/m³Nampa, 13 August: 26.3 µg/m³Nampa, 14 August: 14.1 µg/m³SunnysideSunnyside, 1 August: 9.4 µg/m³Sunnyside, 2 August: 4.3 µg/m³Sunnyside, 3 August: 37.1 µg/m³Sunnyside, 4 August: 76.8 µg/m³, 10.0× its usual 7.7Sunnyside, 5 August: 67.0 µg/m³, 8.4× its usual 8.0Sunnyside, 6 August: 49.6 µg/m³, 6.2× its usual 8.0Sunnyside, 7 August: 26.8 µg/m³, 3.4× its usual 8.0Sunnyside, 8 August: 10.8 µg/m³Sunnyside, 9 August: 10.6 µg/m³Sunnyside, 10 August: 7.6 µg/m³Sunnyside, 11 August: 6.9 µg/m³Sunnyside, 12 August: 21.2 µg/m³Sunnyside, 13 August: 33.9 µg/m³Sunnyside, 14 August: 21.8 µg/m³Union Hill-Novelty …Union Hill-Novelty Hill, 1 August: no readingUnion Hill-Novelty Hill, 2 August: 0.1 µg/m³Union Hill-Novelty Hill, 3 August: 7.0 µg/m³Union Hill-Novelty Hill, 4 August: 43.1 µg/m³, 8.0× its usual 5.4Union Hill-Novelty Hill, 5 August: 75.6 µg/m³, 14× its usual 5.4Union Hill-Novelty Hill, 6 August: 64.0 µg/m³, 12× its usual 5.4Union Hill-Novelty Hill, 7 August: 37.8 µg/m³Union Hill-Novelty Hill, 8 August: 12.1 µg/m³Union Hill-Novelty Hill, 9 August: 0.7 µg/m³Union Hill-Novelty Hill, 10 August: 2.2 µg/m³Union Hill-Novelty Hill, 11 August: 0.1 µg/m³Union Hill-Novelty Hill, 12 August: 4.2 µg/m³Union Hill-Novelty Hill, 13 August: 17.1 µg/m³Union Hill-Novelty Hill, 14 August: 22.7 µg/m³SpokaneSpokane, 1 August: 15.0 µg/m³Spokane, 2 August: 58.5 µg/m³Spokane, 3 August: 93.1 µg/m³Spokane, 4 August: 68.6 µg/m³, 7.8× its usual 8.8Spokane, 5 August: 45.2 µg/m³, 5.1× its usual 8.8Spokane, 6 August: 54.4 µg/m³, 6.0× its usual 9.0Spokane, 7 August: 49.3 µg/m³, 5.4× its usual 9.2Spokane, 8 August: 50.0 µg/m³, 5.4× its usual 9.2Spokane, 9 August: 75.2 µg/m³, 8.2× its usual 9.2Spokane, 10 August: 36.5 µg/m³Spokane, 11 August: 24.4 µg/m³Spokane, 12 August: 28.4 µg/m³Spokane, 13 August: 18.5 µg/m³Spokane, 14 August: 8.4 µg/m³Coeur d'AleneCoeur d'Alene, 1 August: 9.9 µg/m³Coeur d'Alene, 2 August: 68.3 µg/m³Coeur d'Alene, 3 August: 76.0 µg/m³Coeur d'Alene, 4 August: 50.5 µg/m³, 5.4× its usual 9.3Coeur d'Alene, 5 August: no readingCoeur d'Alene, 6 August: 44.7 µg/m³, 4.6× its usual 9.8Coeur d'Alene, 7 August: 41.0 µg/m³, 4.0× its usual 10.2Coeur d'Alene, 8 August: 54.0 µg/m³, 5.3× its usual 10.2Coeur d'Alene, 9 August: 73.9 µg/m³, 7.4× its usual 10.0Coeur d'Alene, 10 August: 24.2 µg/m³Coeur d'Alene, 11 August: 17.7 µg/m³Coeur d'Alene, 12 August: 23.4 µg/m³Coeur d'Alene, 13 August: 13.2 µg/m³Coeur d'Alene, 14 August: 6.9 µg/m³PascoPasco, 1 August: no readingPasco, 2 August: no readingPasco, 3 August: 26.7 µg/m³Pasco, 4 August: 71.3 µg/m³, 14× its usual 4.7Pasco, 5 August: 62.7 µg/m³, 13× its usual 4.8Pasco, 6 August: 63.3 µg/m³, 13× its usual 4.8Pasco, 7 August: 32.3 µg/m³, 6.5× its usual 4.8Pasco, 8 August: 19.0 µg/m³Pasco, 9 August: 11.8 µg/m³Pasco, 10 August: 6.1 µg/m³Pasco, 11 August: 5.7 µg/m³Pasco, 12 August: 17.4 µg/m³Pasco, 13 August: 26.1 µg/m³Pasco, 14 August: 13.2 µg/m³Tri-CitiesTri-Cities, 1 August: 8.7 µg/m³Tri-Cities, 2 August: 2.9 µg/m³Tri-Cities, 3 August: 32.4 µg/m³Tri-Cities, 4 August: 70.6 µg/m³, 11× its usual 6.2Tri-Cities, 5 August: 65.0 µg/m³, 10× its usual 6.3Tri-Cities, 6 August: 58.3 µg/m³, 9.3× its usual 6.3Tri-Cities, 7 August: 33.0 µg/m³, 5.2× its usual 6.3Tri-Cities, 8 August: 23.0 µg/m³Tri-Cities, 9 August: 13.9 µg/m³Tri-Cities, 10 August: 6.7 µg/m³Tri-Cities, 11 August: 5.4 µg/m³Tri-Cities, 12 August: 18.5 µg/m³Tri-Cities, 13 August: 27.8 µg/m³Tri-Cities, 14 August: 11.8 µg/m³RedmondRedmond, 1 August: 2.7 µg/m³Redmond, 2 August: 3.0 µg/m³Redmond, 3 August: 29.1 µg/m³Redmond, 4 August: 69.8 µg/m³, 6.1× its usual 11.4Redmond, 5 August: 62.0 µg/m³, 5.4× its usual 11.4Redmond, 6 August: 37.9 µg/m³, 3.3× its usual 11.6Redmond, 7 August: 21.4 µg/m³Redmond, 8 August: 14.2 µg/m³Redmond, 9 August: 13.3 µg/m³Redmond, 10 August: 34.2 µg/m³Redmond, 11 August: 34.7 µg/m³Redmond, 12 August: 16.7 µg/m³Redmond, 13 August: 25.9 µg/m³Redmond, 14 August: 25.0 µg/m³North CreekNorth Creek, 1 August: 0.5 µg/m³North Creek, 2 August: 0.9 µg/m³North Creek, 3 August: 6.1 µg/m³North Creek, 4 August: 39.6 µg/m³, 7.9× its usual 4.7North Creek, 5 August: 68.4 µg/m³, 14× its usual 4.7North Creek, 6 August: 53.8 µg/m³, 11× its usual 4.2North Creek, 7 August: 34.8 µg/m³, 7.0× its usual 3.8North Creek, 8 August: 3.3 µg/m³North Creek, 9 August: 1.3 µg/m³North Creek, 10 August: 2.4 µg/m³North Creek, 11 August: no readingNorth Creek, 12 August: 4.4 µg/m³North Creek, 13 August: 15.1 µg/m³North Creek, 14 August: 14.8 µg/m³CorvallisCorvallis, 1 August: 1.8 µg/m³Corvallis, 2 August: 2.4 µg/m³Corvallis, 3 August: 16.9 µg/m³Corvallis, 4 August: 64.9 µg/m³, 13× its usual 3.1Corvallis, 5 August: 66.7 µg/m³, 13× its usual 3.1Corvallis, 6 August: 33.1 µg/m³, 6.6× its usual 3.1Corvallis, 7 August: 9.1 µg/m³Corvallis, 8 August: 5.4 µg/m³Corvallis, 9 August: 2.1 µg/m³Corvallis, 10 August: 2.2 µg/m³Corvallis, 11 August: 2.0 µg/m³Corvallis, 12 August: no readingCorvallis, 13 August: 3.7 µg/m³Corvallis, 14 August: 3.2 µg/m³HermistonHermiston, 1 August: 5.8 µg/m³Hermiston, 2 August: 5.3 µg/m³Hermiston, 3 August: 22.8 µg/m³Hermiston, 4 August: 60.4 µg/m³, 8.3× its usual 7.3Hermiston, 5 August: 64.9 µg/m³, 8.5× its usual 7.6Hermiston, 6 August: 66.1 µg/m³, 8.6× its usual 7.7Hermiston, 7 August: 34.4 µg/m³, 4.5× its usual 7.7Hermiston, 8 August: 14.1 µg/m³Hermiston, 9 August: 5.8 µg/m³Hermiston, 10 August: 7.1 µg/m³Hermiston, 11 August: 5.0 µg/m³Hermiston, 12 August: 5.7 µg/m³Hermiston, 13 August: 21.5 µg/m³Hermiston, 14 August: 19.1 µg/m³SalemSalem, 1 August: 1.9 µg/m³Salem, 2 August: 3.0 µg/m³Salem, 3 August: 21.1 µg/m³Salem, 4 August: 61.2 µg/m³, 12× its usual 3.7Salem, 5 August: 64.4 µg/m³, 13× its usual 3.7Salem, 6 August: 33.4 µg/m³, 6.7× its usual 3.7Salem, 7 August: 11.2 µg/m³Salem, 8 August: 7.2 µg/m³Salem, 9 August: 2.9 µg/m³Salem, 10 August: 2.9 µg/m³Salem, 11 August: 2.9 µg/m³Salem, 12 August: 2.1 µg/m³Salem, 13 August: 6.7 µg/m³Salem, 14 August: 6.4 µg/m³BendBend, 1 August: 3.2 µg/m³Bend, 2 August: 3.1 µg/m³Bend, 3 August: 18.8 µg/m³Bend, 4 August: 64.1 µg/m³, 6.7× its usual 9.6Bend, 5 August: 50.1 µg/m³, 5.2× its usual 9.6Bend, 6 August: 24.9 µg/m³Bend, 7 August: 18.0 µg/m³Bend, 8 August: 12.3 µg/m³Bend, 9 August: 4.7 µg/m³Bend, 10 August: 23.7 µg/m³Bend, 11 August: 23.3 µg/m³Bend, 12 August: 6.5 µg/m³Bend, 13 August: 25.4 µg/m³Bend, 14 August: 18.3 µg/m³BeavertonBeaverton, 1 August: 2.0 µg/m³Beaverton, 2 August: 3.4 µg/m³Beaverton, 3 August: 21.0 µg/m³Beaverton, 4 August: 50.8 µg/m³, 10× its usual 3.7Beaverton, 5 August: 61.8 µg/m³, 12× its usual 3.7Beaverton, 6 August: 35.5 µg/m³, 7.1× its usual 3.7Beaverton, 7 August: 14.7 µg/m³Beaverton, 8 August: 6.6 µg/m³Beaverton, 9 August: 3.1 µg/m³Beaverton, 10 August: 3.1 µg/m³Beaverton, 11 August: 2.4 µg/m³Beaverton, 12 August: 2.2 µg/m³Beaverton, 13 August: 8.3 µg/m³Beaverton, 14 August: 8.3 µg/m³DallasDallas, 1 August: 1.1 µg/m³Dallas, 2 August: 2.0 µg/m³Dallas, 3 August: 19.6 µg/m³Dallas, 4 August: 60.3 µg/m³, 12× its usual 2.5Dallas, 5 August: 57.7 µg/m³, 12× its usual 2.6Dallas, 6 August: 42.4 µg/m³, 8.5× its usual 2.6Dallas, 7 August: 10.4 µg/m³Dallas, 8 August: 4.8 µg/m³Dallas, 9 August: 1.4 µg/m³Dallas, 10 August: 1.7 µg/m³Dallas, 11 August: 1.4 µg/m³Dallas, 12 August: 1.0 µg/m³Dallas, 13 August: 5.3 µg/m³Dallas, 14 August: 4.8 µg/m³TigardTigard, 1 August: 2.5 µg/m³Tigard, 2 August: 4.1 µg/m³Tigard, 3 August: 18.8 µg/m³Tigard, 4 August: 47.2 µg/m³, 9.1× its usual 5.2Tigard, 5 August: 59.5 µg/m³, 11× its usual 5.3Tigard, 6 August: 45.3 µg/m³, 8.7× its usual 5.2Tigard, 7 August: 19.5 µg/m³Tigard, 8 August: 8.2 µg/m³Tigard, 9 August: 4.0 µg/m³Tigard, 10 August: 4.0 µg/m³Tigard, 11 August: 3.1 µg/m³Tigard, 12 August: 3.1 µg/m³Tigard, 13 August: 10.9 µg/m³Tigard, 14 August: 11.0 µg/m³MeridianMeridian, 1 August: 36.4 µg/m³Meridian, 2 August: 40.4 µg/m³Meridian, 3 August: 59.2 µg/m³Meridian, 4 August: 58.6 µg/m³, 6.9× its usual 8.5Meridian, 5 August: 30.1 µg/m³, 3.5× its usual 8.5Meridian, 6 August: 28.8 µg/m³, 3.5× its usual 8.3Meridian, 7 August: 58.0 µg/m³, 7.0× its usual 8.3Meridian, 8 August: 59.0 µg/m³, 7.0× its usual 8.4Meridian, 9 August: 32.0 µg/m³, 3.8× its usual 8.5Meridian, 10 August: 31.8 µg/m³, 3.7× its usual 8.7Meridian, 11 August: 34.8 µg/m³, 4.0× its usual 8.6Meridian, 12 August: 24.9 µg/m³Meridian, 13 August: 22.9 µg/m³Meridian, 14 August: 12.2 µg/m³WoodburnWoodburn, 1 August: 1.8 µg/m³Woodburn, 2 August: 2.4 µg/m³Woodburn, 3 August: 16.7 µg/m³Woodburn, 4 August: 50.2 µg/m³, 10× its usual 2.9Woodburn, 5 August: 57.8 µg/m³, 12× its usual 2.9Woodburn, 6 August: 39.6 µg/m³, 7.9× its usual 2.9Woodburn, 7 August: 9.8 µg/m³Woodburn, 8 August: 5.3 µg/m³Woodburn, 9 August: 2.3 µg/m³Woodburn, 10 August: 2.2 µg/m³Woodburn, 11 August: 1.9 µg/m³Woodburn, 12 August: 1.8 µg/m³Woodburn, 13 August: 5.9 µg/m³Woodburn, 14 August: 4.9 µg/m³KirklandKirkland, 1 August: no readingKirkland, 2 August: no readingKirkland, 3 August: 8.9 µg/m³Kirkland, 4 August: 46.5 µg/m³, 9.3× its usual 3.9Kirkland, 5 August: 56.7 µg/m³, 11× its usual 3.9Kirkland, 6 August: 52.2 µg/m³, 10× its usual 4.7Kirkland, 7 August: 34.2 µg/m³, 6.8× its usual 4.7Kirkland, 8 August: 7.1 µg/m³Kirkland, 9 August: 0.9 µg/m³Kirkland, 10 August: 1.5 µg/m³Kirkland, 11 August: 0.0 µg/m³Kirkland, 12 August: 3.9 µg/m³Kirkland, 13 August: 12.5 µg/m³Kirkland, 14 August: 13.2 µg/m³Twin FallsTwin Falls, 1 August: 13.8 µg/m³Twin Falls, 2 August: 53.1 µg/m³Twin Falls, 3 August: 25.0 µg/m³Twin Falls, 4 August: 56.1 µg/m³, 8.5× its usual 6.6Twin Falls, 5 August: 30.0 µg/m³, 4.5× its usual 6.6Twin Falls, 6 August: 18.0 µg/m³Twin Falls, 7 August: 28.2 µg/m³, 4.3× its usual 6.6Twin Falls, 8 August: 48.1 µg/m³, 7.1× its usual 6.8Twin Falls, 9 August: 43.9 µg/m³, 6.4× its usual 6.9Twin Falls, 10 August: 27.0 µg/m³, 3.9× its usual 7.0Twin Falls, 11 August: 28.9 µg/m³, 4.1× its usual 7.1Twin Falls, 12 August: 31.2 µg/m³Twin Falls, 13 August: 15.2 µg/m³Twin Falls, 14 August: 11.3 µg/m³BoiseBoise, 1 August: 36.3 µg/m³Boise, 2 August: 54.8 µg/m³Boise, 3 August: 52.1 µg/m³Boise, 4 August: 54.0 µg/m³, 7.4× its usual 7.3Boise, 5 August: 26.9 µg/m³, 3.7× its usual 7.3Boise, 6 August: 26.9 µg/m³, 3.7× its usual 7.3Boise, 7 August: 54.7 µg/m³, 7.5× its usual 7.3Boise, 8 August: 54.8 µg/m³, 7.5× its usual 7.3Boise, 9 August: 34.1 µg/m³, 4.7× its usual 7.3Boise, 10 August: 34.7 µg/m³, 4.8× its usual 7.3Boise, 11 August: 41.1 µg/m³, 5.6× its usual 7.3Boise, 12 August: 30.6 µg/m³Boise, 13 August: 23.8 µg/m³Boise, 14 August: 12.0 µg/m³McMinnvilleMcMinnville, 1 August: 1.6 µg/m³McMinnville, 2 August: 1.7 µg/m³McMinnville, 3 August: 8.9 µg/m³McMinnville, 4 August: 35.7 µg/m³, 7.1× its usual 2.7McMinnville, 5 August: 54.1 µg/m³, 11× its usual 2.7McMinnville, 6 August: 28.9 µg/m³, 5.8× its usual 2.7McMinnville, 7 August: 9.1 µg/m³McMinnville, 8 August: 7.1 µg/m³McMinnville, 9 August: 2.7 µg/m³McMinnville, 10 August: 2.7 µg/m³McMinnville, 11 August: 2.4 µg/m³McMinnville, 12 August: 2.0 µg/m³McMinnville, 13 August: 7.4 µg/m³McMinnville, 14 August: 4.8 µg/m³PortlandPortland, 1 August: 2.0 µg/m³Portland, 2 August: 3.3 µg/m³Portland, 3 August: 17.1 µg/m³Portland, 4 August: 40.7 µg/m³, 8.1× its usual 3.7Portland, 5 August: 53.0 µg/m³, 11× its usual 3.8Portland, 6 August: 27.1 µg/m³, 5.4× its usual 3.8Portland, 7 August: 11.5 µg/m³Portland, 8 August: 4.6 µg/m³Portland, 9 August: 3.3 µg/m³Portland, 10 August: 3.4 µg/m³Portland, 11 August: 2.7 µg/m³Portland, 12 August: 2.6 µg/m³Portland, 13 August: 7.5 µg/m³Portland, 14 August: 7.8 µg/m³PullmanPullman, 1 August: 15.1 µg/m³Pullman, 2 August: 9.1 µg/m³Pullman, 3 August: 38.8 µg/m³Pullman, 4 August: 41.0 µg/m³, 5.3× its usual 7.8Pullman, 5 August: 29.5 µg/m³, 3.7× its usual 7.9Pullman, 6 August: 52.8 µg/m³, 6.5× its usual 8.1Pullman, 7 August: 52.6 µg/m³, 6.5× its usual 8.1Pullman, 8 August: 24.8 µg/m³Pullman, 9 August: 20.2 µg/m³Pullman, 10 August: 15.0 µg/m³Pullman, 11 August: 12.5 µg/m³Pullman, 12 August: 10.6 µg/m³Pullman, 13 August: 24.7 µg/m³Pullman, 14 August: 13.6 µg/m³LewistonLewiston, 1 August: 29.3 µg/m³Lewiston, 2 August: 6.5 µg/m³Lewiston, 3 August: 32.2 µg/m³Lewiston, 4 August: 43.4 µg/m³, 4.4× its usual 9.9Lewiston, 5 August: 32.1 µg/m³, 3.2× its usual 10.1Lewiston, 6 August: 46.6 µg/m³, 4.4× its usual 10.6Lewiston, 7 August: 51.9 µg/m³, 4.9× its usual 10.6Lewiston, 8 August: 27.0 µg/m³, 2.5× its usual 10.6Lewiston, 9 August: 22.8 µg/m³Lewiston, 10 August: 19.9 µg/m³Lewiston, 11 August: 22.2 µg/m³Lewiston, 12 August: 16.9 µg/m³Lewiston, 13 August: 29.3 µg/m³Lewiston, 14 August: 21.4 µg/m³BothellBothell, 1 August: no readingBothell, 2 August: 0.9 µg/m³Bothell, 3 August: 5.9 µg/m³Bothell, 4 August: 33.7 µg/m³, 6.7× its usual 4.8Bothell, 5 August: 51.5 µg/m³, 10× its usual 4.1Bothell, 6 August: 49.7 µg/m³, 9.9× its usual 4.1Bothell, 7 August: 33.6 µg/m³, 6.7× its usual 3.9Bothell, 8 August: 6.2 µg/m³Bothell, 9 August: 1.6 µg/m³Bothell, 10 August: 3.0 µg/m³Bothell, 11 August: 0.2 µg/m³Bothell, 12 August: 6.0 µg/m³Bothell, 13 August: 16.4 µg/m³Bothell, 14 August: 17.6 µg/m³HillsboroHillsboro, 1 August: 2.1 µg/m³Hillsboro, 2 August: 3.3 µg/m³Hillsboro, 3 August: 23.4 µg/m³Hillsboro, 4 August: 47.7 µg/m³, 9.5× its usual 3.9Hillsboro, 5 August: 50.8 µg/m³, 10× its usual 4.0Hillsboro, 6 August: 31.1 µg/m³, 6.2× its usual 3.9Hillsboro, 7 August: 12.2 µg/m³Hillsboro, 8 August: 5.5 µg/m³Hillsboro, 9 August: 2.8 µg/m³Hillsboro, 10 August: 2.9 µg/m³Hillsboro, 11 August: 2.1 µg/m³Hillsboro, 12 August: 2.0 µg/m³Hillsboro, 13 August: 8.9 µg/m³Hillsboro, 14 August: 6.7 µg/m³VancouverVancouver, 1 August: 2.6 µg/m³Vancouver, 2 August: 4.4 µg/m³Vancouver, 3 August: 16.8 µg/m³Vancouver, 4 August: 39.2 µg/m³, 7.8× its usual 3.2Vancouver, 5 August: 48.7 µg/m³, 9.7× its usual 3.3Vancouver, 6 August: 23.9 µg/m³Vancouver, 7 August: 10.4 µg/m³Vancouver, 8 August: 5.0 µg/m³Vancouver, 9 August: 4.0 µg/m³Vancouver, 10 August: 3.5 µg/m³Vancouver, 11 August: 2.6 µg/m³Vancouver, 12 August: 3.3 µg/m³Vancouver, 13 August: 7.1 µg/m³Vancouver, 14 August: 6.6 µg/m³MoscowMoscow, 1 August: 16.5 µg/m³Moscow, 2 August: 7.7 µg/m³Moscow, 3 August: 41.5 µg/m³Moscow, 4 August: 40.0 µg/m³, 4.1× its usual 9.7Moscow, 5 August: 27.4 µg/m³, 2.8× its usual 9.8Moscow, 6 August: 43.4 µg/m³, 4.4× its usual 9.8Moscow, 7 August: 46.5 µg/m³, 4.7× its usual 9.8Moscow, 8 August: 19.1 µg/m³Moscow, 9 August: 29.9 µg/m³, 3.1× its usual 9.7Moscow, 10 August: 15.6 µg/m³Moscow, 11 August: 12.3 µg/m³Moscow, 12 August: 15.9 µg/m³Moscow, 13 August: 24.3 µg/m³Moscow, 14 August: 13.8 µg/m³Salmon CreekSalmon Creek, 1 August: 2.3 µg/m³Salmon Creek, 2 August: 3.4 µg/m³Salmon Creek, 3 August: 16.5 µg/m³Salmon Creek, 4 August: 38.7 µg/m³, 7.7× its usual 4.3Salmon Creek, 5 August: 46.1 µg/m³, 9.2× its usual 4.3Salmon Creek, 6 August: 22.7 µg/m³Salmon Creek, 7 August: 12.5 µg/m³Salmon Creek, 8 August: 4.5 µg/m³Salmon Creek, 9 August: 3.6 µg/m³Salmon Creek, 10 August: 3.3 µg/m³Salmon Creek, 11 August: 2.6 µg/m³Salmon Creek, 12 August: 2.5 µg/m³Salmon Creek, 13 August: 6.3 µg/m³Salmon Creek, 14 August: 5.6 µg/m³AuburnAuburn, 1 August: 2.3 µg/m³Auburn, 2 August: 3.2 µg/m³Auburn, 3 August: 6.1 µg/m³Auburn, 4 August: 30.9 µg/m³, 5.6× its usual 5.5Auburn, 5 August: 44.5 µg/m³, 8.1× its usual 5.5Auburn, 6 August: 40.5 µg/m³, 7.4× its usual 5.5Auburn, 7 August: 25.2 µg/m³, 4.6× its usual 5.5Auburn, 8 August: 8.0 µg/m³Auburn, 9 August: 5.2 µg/m³Auburn, 10 August: 4.4 µg/m³Auburn, 11 August: 4.3 µg/m³Auburn, 12 August: 3.4 µg/m³Auburn, 13 August: 8.4 µg/m³Auburn, 14 August: 8.5 µg/m³CentraliaCentralia, 1 August: 2.9 µg/m³Centralia, 2 August: 3.9 µg/m³Centralia, 3 August: 13.6 µg/m³Centralia, 4 August: 32.3 µg/m³, 6.5× its usual 4.0Centralia, 5 August: 43.2 µg/m³, 8.6× its usual 4.0Centralia, 6 August: 20.9 µg/m³Centralia, 7 August: 11.3 µg/m³Centralia, 8 August: 4.9 µg/m³Centralia, 9 August: 4.0 µg/m³Centralia, 10 August: 3.4 µg/m³Centralia, 11 August: 2.9 µg/m³Centralia, 12 August: no readingCentralia, 13 August: 6.1 µg/m³Centralia, 14 August: 4.0 µg/m³ParklandParkland, 1 August: 1.3 µg/m³Parkland, 2 August: 3.4 µg/m³Parkland, 3 August: 5.5 µg/m³Parkland, 4 August: 26.8 µg/m³, 5.4× its usual 3.6Parkland, 5 August: 42.4 µg/m³, 8.5× its usual 3.7Parkland, 6 August: 38.9 µg/m³, 7.8× its usual 3.6Parkland, 7 August: 14.6 µg/m³Parkland, 8 August: 6.3 µg/m³Parkland, 9 August: 4.3 µg/m³Parkland, 10 August: 3.6 µg/m³Parkland, 11 August: 2.6 µg/m³Parkland, 12 August: 1.6 µg/m³Parkland, 13 August: 8.9 µg/m³Parkland, 14 August: 5.0 µg/m³MilwaukieMilwaukie, 1 August: 2.2 µg/m³Milwaukie, 2 August: 2.6 µg/m³Milwaukie, 3 August: 12.2 µg/m³Milwaukie, 4 August: 35.5 µg/m³, 7.1× its usual 3.6Milwaukie, 5 August: 41.2 µg/m³, 8.2× its usual 3.7Milwaukie, 6 August: 22.4 µg/m³Milwaukie, 7 August: 7.9 µg/m³Milwaukie, 8 August: 3.6 µg/m³Milwaukie, 9 August: 2.7 µg/m³Milwaukie, 10 August: 2.6 µg/m³Milwaukie, 11 August: 2.3 µg/m³Milwaukie, 12 August: 2.3 µg/m³Milwaukie, 13 August: 5.4 µg/m³Milwaukie, 14 August: 5.1 µg/m³KentKent, 1 August: 1.3 µg/m³Kent, 2 August: 3.4 µg/m³Kent, 3 August: 8.5 µg/m³Kent, 4 August: 29.2 µg/m³, 4.5× its usual 6.5Kent, 5 August: 41.1 µg/m³, 8.2× its usual 4.4Kent, 6 August: 39.6 µg/m³, 7.9× its usual 4.1Kent, 7 August: 20.6 µg/m³Kent, 8 August: 8.3 µg/m³Kent, 9 August: no readingKent, 10 August: no readingKent, 11 August: 4.0 µg/m³Kent, 12 August: no readingKent, 13 August: 8.4 µg/m³Kent, 14 August: 7.7 µg/m³VernonVernon, 1 August: 28.3 µg/m³Vernon, 2 August: 26.4 µg/m³Vernon, 3 August: 8.7 µg/m³Vernon, 4 August: 19.3 µg/m³Vernon, 5 August: 61.7 µg/m³, 6.7× its usual 9.2Vernon, 6 August: 122.0 µg/m³, 13× its usual 9.1Vernon, 7 August: 102.0 µg/m³, 11× its usual 9.2Vernon, 8 August: 71.8 µg/m³, 7.8× its usual 9.2Vernon, 9 August: 102.0 µg/m³, 11× its usual 9.2Vernon, 10 August: 142.0 µg/m³Vernon, 11 August: 118.0 µg/m³Vernon, 12 August: 7.5 µg/m³Vernon, 13 August: 9.3 µg/m³Vernon, 14 August: 8.7 µg/m³CranbrookCranbrook, 1 August: 14.5 µg/m³Cranbrook, 2 August: 39.8 µg/m³Cranbrook, 3 August: 22.2 µg/m³Cranbrook, 4 August: 15.7 µg/m³Cranbrook, 5 August: 26.0 µg/m³, 3.1× its usual 8.5Cranbrook, 6 August: 67.0 µg/m³, 7.7× its usual 8.7Cranbrook, 7 August: 84.2 µg/m³, 9.4× its usual 9.0Cranbrook, 8 August: 63.8 µg/m³, 6.8× its usual 9.4Cranbrook, 9 August: 93.4 µg/m³, 10× its usual 9.1Cranbrook, 10 August: 68.4 µg/m³Cranbrook, 11 August: 58.5 µg/m³Cranbrook, 12 August: 29.2 µg/m³Cranbrook, 13 August: 8.2 µg/m³Cranbrook, 14 August: 2.3 µg/m³KelownaKelowna, 1 August: 22.4 µg/m³Kelowna, 2 August: 3.1 µg/m³Kelowna, 3 August: 14.8 µg/m³Kelowna, 4 August: 18.4 µg/m³Kelowna, 5 August: 39.6 µg/m³, 4.9× its usual 8.1Kelowna, 6 August: 67.1 µg/m³, 8.3× its usual 8.1Kelowna, 7 August: 59.8 µg/m³, 7.4× its usual 8.1Kelowna, 8 August: 20.2 µg/m³Kelowna, 9 August: 40.8 µg/m³, 4.9× its usual 8.3Kelowna, 10 August: no readingKelowna, 11 August: 94.3 µg/m³Kelowna, 12 August: 15.3 µg/m³Kelowna, 13 August: 16.3 µg/m³Kelowna, 14 August: 8.4 µg/m³AbbotsfordAbbotsford, 1 August: 2.4 µg/m³Abbotsford, 2 August: 3.3 µg/m³Abbotsford, 3 August: 7.6 µg/m³Abbotsford, 4 August: 18.4 µg/m³Abbotsford, 5 August: 50.1 µg/m³, 9.8× its usual 5.1Abbotsford, 6 August: 37.9 µg/m³, 7.4× its usual 5.1Abbotsford, 7 August: 16.9 µg/m³Abbotsford, 8 August: 7.0 µg/m³Abbotsford, 9 August: 5.9 µg/m³Abbotsford, 10 August: 4.4 µg/m³Abbotsford, 11 August: 4.4 µg/m³Abbotsford, 12 August: 6.4 µg/m³Abbotsford, 13 August: 14.0 µg/m³Abbotsford, 14 August: 13.1 µg/m³Inglewood-Finn HillInglewood-Finn Hill, 1 August: no readingInglewood-Finn Hill, 2 August: no readingInglewood-Finn Hill, 3 August: no readingInglewood-Finn Hill, 4 August: no readingInglewood-Finn Hill, 5 August: 49.2 µg/m³, 9.8× its usual 4.2Inglewood-Finn Hill, 6 August: 49.0 µg/m³, 9.8× its usual 4.3Inglewood-Finn Hill, 7 August: 34.1 µg/m³, 6.8× its usual 4.2Inglewood-Finn Hill, 8 August: 9.7 µg/m³Inglewood-Finn Hill, 9 August: 3.0 µg/m³Inglewood-Finn Hill, 10 August: 4.7 µg/m³Inglewood-Finn Hill, 11 August: 1.4 µg/m³Inglewood-Finn Hill, 12 August: 4.6 µg/m³Inglewood-Finn Hill, 13 August: 14.4 µg/m³Inglewood-Finn Hill, 14 August: 14.9 µg/m³CoquitlamCoquitlam, 1 August: 2.5 µg/m³Coquitlam, 2 August: 3.1 µg/m³Coquitlam, 3 August: 3.2 µg/m³Coquitlam, 4 August: 9.7 µg/m³Coquitlam, 5 August: 46.9 µg/m³, 8.5× its usual 5.5Coquitlam, 6 August: 37.5 µg/m³, 6.9× its usual 5.4Coquitlam, 7 August: 14.8 µg/m³Coquitlam, 8 August: 8.2 µg/m³Coquitlam, 9 August: 5.5 µg/m³Coquitlam, 10 August: 4.5 µg/m³Coquitlam, 11 August: 4.0 µg/m³Coquitlam, 12 August: 5.6 µg/m³Coquitlam, 13 August: 9.7 µg/m³Coquitlam, 14 August: 15.8 µg/m³BozemanBozeman, 1 August: 10.9 µg/m³Bozeman, 2 August: 24.4 µg/m³Bozeman, 3 August: 28.5 µg/m³Bozeman, 4 August: 12.5 µg/m³Bozeman, 5 August: 15.4 µg/m³Bozeman, 6 August: 31.0 µg/m³, 4.1× its usual 7.6Bozeman, 7 August: 44.8 µg/m³, 5.7× its usual 7.9Bozeman, 8 August: 65.0 µg/m³, 8.2× its usual 7.9Bozeman, 9 August: 45.7 µg/m³, 5.8× its usual 7.9Bozeman, 10 August: 61.0 µg/m³Bozeman, 11 August: 42.8 µg/m³Bozeman, 12 August: 26.0 µg/m³Bozeman, 13 August: 13.1 µg/m³Bozeman, 14 August: 5.3 µg/m³ButteButte, 1 August: 20.6 µg/m³Butte, 2 August: 22.3 µg/m³Butte, 3 August: 30.6 µg/m³Butte, 4 August: 16.6 µg/m³Butte, 5 August: 22.9 µg/m³Butte, 6 August: 30.6 µg/m³, 4.3× its usual 7.2Butte, 7 August: 59.8 µg/m³, 8.3× its usual 7.2Butte, 8 August: 57.6 µg/m³, 7.7× its usual 7.5Butte, 9 August: 36.1 µg/m³, 4.7× its usual 7.7Butte, 10 August: 33.3 µg/m³Butte, 11 August: 32.3 µg/m³Butte, 12 August: 25.5 µg/m³Butte, 13 August: 12.1 µg/m³Butte, 14 August: 4.8 µg/m³MissoulaMissoula, 1 August: 25.4 µg/m³Missoula, 2 August: 18.9 µg/m³Missoula, 3 August: 49.4 µg/m³Missoula, 4 August: 23.1 µg/m³Missoula, 5 August: 22.0 µg/m³Missoula, 6 August: 39.5 µg/m³, 5.6× its usual 7.1Missoula, 7 August: 37.6 µg/m³, 5.3× its usual 7.1Missoula, 8 August: 26.9 µg/m³, 3.7× its usual 7.2Missoula, 9 August: 46.7 µg/m³, 6.4× its usual 7.3Missoula, 10 August: 55.1 µg/m³Missoula, 11 August: 47.1 µg/m³Missoula, 12 August: 30.5 µg/m³Missoula, 13 August: 7.8 µg/m³Missoula, 14 August: 8.9 µg/m³BillingsBillings, 1 August: 14.8 µg/m³Billings, 2 August: 22.9 µg/m³Billings, 3 August: 36.6 µg/m³Billings, 4 August: 12.9 µg/m³Billings, 5 August: 14.2 µg/m³Billings, 6 August: 24.9 µg/m³Billings, 7 August: 24.8 µg/m³Billings, 8 August: 41.4 µg/m³, 5.7× its usual 7.3Billings, 9 August: 40.6 µg/m³, 5.6× its usual 7.3Billings, 10 August: 32.3 µg/m³Billings, 11 August: 26.1 µg/m³Billings, 12 August: 20.6 µg/m³Billings, 13 August: 10.1 µg/m³Billings, 14 August: 3.6 µg/m³1 Aug35791113
The 60 cities with the highest readings of 99, 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
WenatcheeWashington, United States4 204.04 August5.041×
EugeneOregon, United States3 120.05 August4.424×
YakimaWashington, United States4 100.04 August5.817×
Oregon CityOregon, United States3 86.25 August3.517×
CanbyOregon, United States3 86.15 August4.117×
KamloopsBritish Columbia, Canada6 191.07 August11.217×
AlbanyOregon, United States3 83.35 August3.617×
The DallesOregon, United States3 83.86 August5.116×
GreshamOregon, United States3 79.95 August3.516×
EllensburgWashington, United States3 84.04 August5.515×
Walla WallaWashington, United States4 108.05 August7.215×
PascoWashington, United States4 71.34 August4.714×
Union Hill-Novelty HillWashington, United States3 75.65 August5.414×
North CreekWashington, United States4 68.45 August4.714×
ChilliwackBritish Columbia, Canada3 81.55 August6.014×
VernonBritish Columbia, Canada5 122.06 August9.113×
CorvallisOregon, United States3 66.75 August3.113×
SalemOregon, United States3 64.45 August3.713×
BeavertonOregon, United States3 61.85 August3.712×
DallasOregon, United States3 60.34 August2.512×
Moses LakeWashington, United States6 87.19 August7.512×
WoodburnOregon, United States3 57.85 August2.912×
Tri-CitiesWashington, United States4 70.64 August6.211×
KirklandWashington, United States4 56.75 August3.911×
TigardOregon, United States3 59.55 August5.311×
PendletonOregon, United States5 86.35 August8.011×
McMinnvilleOregon, United States3 54.15 August2.711×
PortlandOregon, United States3 53.05 August3.811×
CranbrookBritish Columbia, Canada5 93.49 August9.110×
BothellWashington, United States4 51.55 August4.110×
HillsboroOregon, United States3 50.85 August4.010×
SunnysideWashington, United States4 76.84 August7.710×
AbbotsfordBritish Columbia, Canada2 50.15 August5.19.8×
Inglewood-Finn HillWashington, United States3 49.25 August4.29.8×
VancouverWashington, United States2 48.75 August3.39.7×
Salmon CreekWashington, United States2 46.15 August4.39.2×
Spokane ValleyWashington, United States6 82.89 August9.19.1×
HermistonOregon, United States4 66.16 August7.78.6×
CentraliaWashington, United States2 43.25 August4.08.6×
Twin FallsIdaho, United States7 56.14 August6.68.5×
CoquitlamBritish Columbia, Canada2 46.95 August5.58.5×
ParklandWashington, United States3 42.45 August3.78.5×
KelownaBritish Columbia, Canada4 67.16 August8.18.3×
ButteMontana, United States4 59.87 August7.28.3×
SpokaneWashington, United States6 75.29 August9.28.2×
BozemanMontana, United States4 65.08 August7.98.2×
MilwaukieOregon, United States2 41.25 August3.78.2×
KentWashington, United States3 41.15 August4.48.2×
NampaIdaho, United States8 77.57 August9.68.1×
AuburnWashington, United States4 44.55 August5.58.1×
BellevueWashington, United States3 38.35 August4.37.7×
BoiseIdaho, United States8 54.88 August7.37.5×
Forest GroveOregon, United States2 37.55 August2.77.5×
Coeur d'AleneIdaho, United States5 73.99 August10.07.4×
RentonWashington, United States2 36.76 August5.07.3×
TacomaWashington, United States3 36.65 August4.97.3×
North VancouverBritish Columbia, Canada2 36.55 August4.57.3×
Port CoquitlamBritish Columbia, Canada2 36.25 August4.97.2×
BurienWashington, United States2 35.46 August3.77.1×
MeridianIdaho, United States8 59.08 August8.47.0×
LongviewWashington, United States2 34.25 August4.16.8×
LangleyBritish Columbia, Canada2 34.25 August4.66.8×
BendOregon, United States2 64.14 August9.66.7×
PullmanWashington, United States4 52.86 August8.16.5×
West VancouverBritish Columbia, Canada2 32.35 August4.96.5×
MissoulaMontana, United States4 46.79 August7.36.4×
Grants PassOregon, United States2 32.25 August4.86.4×
ShorelineWashington, United States2 32.26 August4.96.4×
LaceyWashington, United States1 31.25 August3.16.2×
RedmondOregon, United States3 69.84 August11.46.1×
BurnabyBritish Columbia, Canada1 31.15 August5.16.1×
Picnic Point-North LynnwoodWashington, United States1 34.05 August5.76.0×
BremertonWashington, United States1 29.56 August4.05.9×
RoseburgOregon, United States2 29.35 August3.45.9×
BillingsMontana, United States2 41.48 August7.35.7×
Strawberry HillBritish Columbia, Canada1 28.55 August4.75.7×
Columbia CityWashington, United States2 35.96 August6.75.4×
MarysvilleWashington, United States1 27.25 August3.25.4×
SheridanWyoming, United States3 36.88 August6.95.3×
SquamishBritish Columbia, Canada2 35.96 August6.85.3×
Port AlberniBritish Columbia, Canada1 26.56 August3.85.3×
SeattleWashington, United States2 27.56 August5.45.1×
LewistonIdaho, United States5 51.97 August10.64.9×
BellinghamWashington, United States1 26.76 August5.54.9×
PocatelloIdaho, United States1 27.89 August5.84.8×
MoscowIdaho, United States5 46.57 August9.84.7×
AltamontOregon, United States1 36.95 August7.84.7×
Idaho FallsIdaho, United States1 26.79 August5.94.5×
HelenaMontana, United States4 39.56 August8.94.4×
AshlandOregon, United States1 27.66 August6.94.0×
MedfordOregon, United States1 26.76 August6.93.9×
GilletteWyoming, United States2 26.58 August6.83.9×
Brigham CityUtah, United States1 26.75 August7.43.6×
TooeleUtah, United States1 25.15 August7.13.5×
West JordanUtah, United States1 26.35 August8.03.3×
Great FallsMontana, United States3 40.58 August13.33.0×
MillcreekUtah, United States1 25.45 August8.82.9×
AirdrieAlberta, Canada1 26.29 August10.82.4×
CalgaryAlberta, Canada1 27.69 August13.22.1×

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 11 of 141 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 141.

Use this page

SmogRank, North-western United States and Canada, 4 to 11 August 2026: 99 cities with PM2.5 at twice their usual or more, 4 to 11 August 2026, smogrank.com/episodes/2026-08-04-north-western-united-states-and-canada (accessed 4 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.