SmogRank / Episodes / Canada
North-western Canada and United States, August 2024
For 5 days, from 14 to 18 August 2024, 23 cities in Canada and the United States had PM2.5 at least twice their usual for the time of year. The worst reading was Fort Saskatchewan, Alberta, Canada: 172.0 µg/m³ on 14 August, about 17× its usual 10.1. Ended 18 August.
No cause named We have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached 23 in 2 countries
Days 5 14 to 18 August 2024
Worst day 15 August 19 cities counted
Furthest above usual 17× Fort Saskatchewan
Day by day
Play 15 August 19 cities at twice their usual or more
Columbia Falls Cranbrook Great Falls Creston Missoula Sandpoint Helena Valley West Central Helena Castlegar Coeur d'Alene Butte Spokane Valley Mead Spokane Airway Heights Bozeman Moscow Pullman Vernon Lewiston Kelowna Penticton Billings Lockwood Prince Albert Kamloops Walla Walla Moses Lake Ephrata Quincy Tri-Cities Pendleton Wenatchee Hermiston Prosser Hope Sunnyside Ellensburg Toppenish Yakima Agassiz Williams Lake Chilliwack Abbotsford Quesnel Mission Lynden Marysville Mount Vernon Bellingham Langley Picnic Point-North Lynnwood Bellevue Port Coquitlam Coquitlam Whistler Renton Shoreline Anacortes The Dalles Seattle Auburn Strawberry Hill Oak Harbor White Center Burnaby North Vancouver Hood River Squamish Port Townsend Delta Tacoma Vancouver West Vancouver Parkland Richmond Bremerton Gibsons Lacey Victoria Langford Port Angeles Shelton North Cowichan Duncan Centralia Chehalis Nanaimo Harewood Salmon Creek Ridgefield Longview Vancouver Flin Flon North Portland Aberdeen Edson Prince George Lewistown Lethbridge Glendive Calgary Miles City Grand Centre Regina Estevan Havre Sherwood Park Airdrie Red Deer Saskatoon Medicine Hat Grande Prairie Fort McMurray Drayton Valley St. Albert Edmonton Swift Current Fort Saskatchewan 11 Aug 12 13 14 15 16 17 18 19 20 21 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
Fort Saskatchewan Fort Saskatchewan, 11 August: 16.7 µg/m³ Fort Saskatchewan, 12 August: 11.4 µg/m³ Fort Saskatchewan, 13 August: 10.4 µg/m³ Fort Saskatchewan, 14 August: 172.0 µg/m³, 17× its usual 10.1 Fort Saskatchewan, 15 August: 81.0 µg/m³, 8.2× its usual 9.9 Fort Saskatchewan, 16 August: 30.1 µg/m³, 3.0× its usual 10.0 Fort Saskatchewan, 17 August: 40.2 µg/m³, 4.0× its usual 10.0 Fort Saskatchewan, 18 August: 32.8 µg/m³, 3.3× its usual 10.0 Fort Saskatchewan, 19 August: 24.1 µg/m³ Fort Saskatchewan, 20 August: 11.6 µg/m³ Fort Saskatchewan, 21 August: 12.5 µg/m³ Edmonton Edmonton, 11 August: 17.4 µg/m³ Edmonton, 12 August: 13.2 µg/m³ Edmonton, 13 August: 13.6 µg/m³ Edmonton, 14 August: 152.0 µg/m³, 13× its usual 12.1 Edmonton, 15 August: 104.4 µg/m³, 8.8× its usual 11.8 Edmonton, 16 August: 31.9 µg/m³, 2.7× its usual 11.9 Edmonton, 17 August: 41.8 µg/m³, 3.5× its usual 11.9 Edmonton, 18 August: 39.3 µg/m³, 3.2× its usual 12.1 Edmonton, 19 August: 24.7 µg/m³ Edmonton, 20 August: 12.8 µg/m³ Edmonton, 21 August: 15.5 µg/m³ St. Albert St. Albert, 11 August: 12.7 µg/m³ St. Albert, 12 August: 10.0 µg/m³ St. Albert, 13 August: 9.8 µg/m³ St. Albert, 14 August: 102.0 µg/m³, 12× its usual 8.2 St. Albert, 15 August: 68.0 µg/m³, 8.3× its usual 8.2 St. Albert, 16 August: 19.5 µg/m³ St. Albert, 17 August: 26.7 µg/m³, 3.3× its usual 8.2 St. Albert, 18 August: 20.7 µg/m³ St. Albert, 19 August: 18.2 µg/m³ St. Albert, 20 August: 8.6 µg/m³ St. Albert, 21 August: 13.0 µg/m³ Fort McMurray Fort McMurray, 11 August: 25.4 µg/m³ Fort McMurray, 12 August: 14.4 µg/m³ Fort McMurray, 13 August: 30.7 µg/m³ Fort McMurray, 14 August: 58.8 µg/m³, 4.8× its usual 12.3 Fort McMurray, 15 August: 42.3 µg/m³, 3.6× its usual 11.8 Fort McMurray, 16 August: 35.2 µg/m³, 3.0× its usual 11.8 Fort McMurray, 17 August: 107.0 µg/m³, 8.9× its usual 12.0 Fort McMurray, 18 August: 119.0 µg/m³, 9.6× its usual 12.4 Fort McMurray, 19 August: 46.4 µg/m³ Fort McMurray, 20 August: 24.2 µg/m³ Fort McMurray, 21 August: 55.9 µg/m³ Grand Centre Grand Centre, 11 August: 21.1 µg/m³ Grand Centre, 12 August: 15.2 µg/m³ Grand Centre, 13 August: 13.1 µg/m³ Grand Centre, 14 August: 54.9 µg/m³, 5.4× its usual 10.2 Grand Centre, 15 August: 38.0 µg/m³, 4.0× its usual 9.6 Grand Centre, 16 August: 31.3 µg/m³, 3.3× its usual 9.6 Grand Centre, 17 August: 41.4 µg/m³, 4.3× its usual 9.6 Grand Centre, 18 August: 33.6 µg/m³, 3.5× its usual 9.7 Grand Centre, 19 August: 24.5 µg/m³ Grand Centre, 20 August: 6.1 µg/m³ Grand Centre, 21 August: 16.2 µg/m³ Airdrie Airdrie, 11 August: no reading Airdrie, 12 August: no reading Airdrie, 13 August: 14.9 µg/m³ Airdrie, 14 August: 38.3 µg/m³, 4.0× its usual 9.5 Airdrie, 15 August: 65.1 µg/m³, 7.1× its usual 9.2 Airdrie, 16 August: no reading Airdrie, 17 August: 22.5 µg/m³ Airdrie, 18 August: 15.2 µg/m³ Airdrie, 19 August: 9.9 µg/m³ Airdrie, 20 August: 5.8 µg/m³ Airdrie, 21 August: 5.1 µg/m³ Calgary Calgary, 11 August: 14.1 µg/m³ Calgary, 12 August: 13.4 µg/m³ Calgary, 13 August: 16.1 µg/m³ Calgary, 14 August: 34.1 µg/m³, 2.7× its usual 12.5 Calgary, 15 August: 57.4 µg/m³, 4.6× its usual 12.5 Calgary, 16 August: 39.3 µg/m³, 3.1× its usual 12.5 Calgary, 17 August: 28.6 µg/m³, 2.3× its usual 12.5 Calgary, 18 August: 17.3 µg/m³ Calgary, 19 August: 11.9 µg/m³ Calgary, 20 August: 7.8 µg/m³ Calgary, 21 August: 7.7 µg/m³ Medicine Hat Medicine Hat, 11 August: 11.7 µg/m³ Medicine Hat, 12 August: 12.7 µg/m³ Medicine Hat, 13 August: 14.0 µg/m³ Medicine Hat, 14 August: 29.9 µg/m³, 3.4× its usual 8.8 Medicine Hat, 15 August: 78.3 µg/m³, 8.9× its usual 8.8 Medicine Hat, 16 August: 35.2 µg/m³, 4.0× its usual 8.7 Medicine Hat, 17 August: 11.5 µg/m³ Medicine Hat, 18 August: 10.1 µg/m³ Medicine Hat, 19 August: 8.7 µg/m³ Medicine Hat, 20 August: 6.1 µg/m³ Medicine Hat, 21 August: 8.0 µg/m³ Saskatoon Saskatoon, 11 August: no reading Saskatoon, 12 August: 14.0 µg/m³ Saskatoon, 13 August: 14.1 µg/m³ Saskatoon, 14 August: 29.0 µg/m³, 2.3× its usual 12.6 Saskatoon, 15 August: 99.0 µg/m³, 8.1× its usual 12.2 Saskatoon, 16 August: 40.8 µg/m³, 3.6× its usual 11.3 Saskatoon, 17 August: 41.3 µg/m³, 3.7× its usual 11.3 Saskatoon, 18 August: 32.4 µg/m³, 2.9× its usual 11.3 Saskatoon, 19 August: 24.3 µg/m³ Saskatoon, 20 August: 11.4 µg/m³ Saskatoon, 21 August: 11.4 µg/m³ Swift Current Swift Current, 11 August: 13.5 µg/m³ Swift Current, 12 August: 9.9 µg/m³ Swift Current, 13 August: 11.9 µg/m³ Swift Current, 14 August: 16.3 µg/m³ Swift Current, 15 August: 137.0 µg/m³, 15× its usual 9.3 Swift Current, 16 August: 64.9 µg/m³, 7.3× its usual 8.9 Swift Current, 17 August: 19.8 µg/m³ Swift Current, 18 August: 10.2 µg/m³ Swift Current, 19 August: 10.2 µg/m³ Swift Current, 20 August: 7.8 µg/m³ Swift Current, 21 August: 7.4 µg/m³ Drayton Valley Drayton Valley, 11 August: 11.4 µg/m³ Drayton Valley, 12 August: 14.2 µg/m³ Drayton Valley, 13 August: 16.4 µg/m³ Drayton Valley, 14 August: 21.8 µg/m³ Drayton Valley, 15 August: 97.0 µg/m³, 12× its usual 8.1 Drayton Valley, 16 August: no reading Drayton Valley, 17 August: 54.0 µg/m³, 6.7× its usual 8.1 Drayton Valley, 18 August: 45.4 µg/m³, 5.3× its usual 8.5 Drayton Valley, 19 August: 36.9 µg/m³ Drayton Valley, 20 August: 12.0 µg/m³ Drayton Valley, 21 August: 13.8 µg/m³ Red Deer Red Deer, 11 August: 11.9 µg/m³ Red Deer, 12 August: 13.9 µg/m³ Red Deer, 13 August: 15.1 µg/m³ Red Deer, 14 August: 22.3 µg/m³ Red Deer, 15 August: 77.6 µg/m³, 7.5× its usual 10.4 Red Deer, 16 August: 28.6 µg/m³, 2.8× its usual 10.4 Red Deer, 17 August: 25.8 µg/m³, 2.4× its usual 10.6 Red Deer, 18 August: 21.9 µg/m³ Red Deer, 19 August: 13.9 µg/m³ Red Deer, 20 August: 4.8 µg/m³ Red Deer, 21 August: 8.7 µg/m³ Grande Prairie Grande Prairie, 11 August: 21.1 µg/m³ Grande Prairie, 12 August: 36.2 µg/m³ Grande Prairie, 13 August: 91.4 µg/m³ Grande Prairie, 14 August: 117.0 µg/m³ Grande Prairie, 15 August: 69.3 µg/m³, 9.1× its usual 7.6 Grande Prairie, 16 August: 22.1 µg/m³ Grande Prairie, 17 August: 19.5 µg/m³ Grande Prairie, 18 August: 16.5 µg/m³ Grande Prairie, 19 August: 10.9 µg/m³ Grande Prairie, 20 August: 10.1 µg/m³ Grande Prairie, 21 August: 26.9 µg/m³ Regina Regina, 11 August: 13.8 µg/m³ Regina, 12 August: 16.2 µg/m³ Regina, 13 August: 9.9 µg/m³ Regina, 14 August: 12.7 µg/m³ Regina, 15 August: 61.0 µg/m³, 5.5× its usual 11.0 Regina, 16 August: 59.8 µg/m³, 5.5× its usual 10.9 Regina, 17 August: 52.2 µg/m³, 4.7× its usual 11.0 Regina, 18 August: 31.5 µg/m³, 2.9× its usual 11.0 Regina, 19 August: 12.5 µg/m³ Regina, 20 August: 10.7 µg/m³ Regina, 21 August: 11.4 µg/m³ Sherwood Park Sherwood Park, 11 August: 11.8 µg/m³ Sherwood Park, 12 August: 9.2 µg/m³ Sherwood Park, 13 August: no reading Sherwood Park, 14 August: no reading Sherwood Park, 15 August: 54.6 µg/m³, 6.7× its usual 8.1 Sherwood Park, 16 August: 18.6 µg/m³ Sherwood Park, 17 August: 26.6 µg/m³, 3.3× its usual 8.1 Sherwood Park, 18 August: 27.1 µg/m³, 3.3× its usual 8.3 Sherwood Park, 19 August: no reading Sherwood Park, 20 August: 9.6 µg/m³ Sherwood Park, 21 August: 11.5 µg/m³ Lethbridge Lethbridge, 11 August: 8.3 µg/m³ Lethbridge, 12 August: 10.8 µg/m³ Lethbridge, 13 August: 9.9 µg/m³ Lethbridge, 14 August: 14.8 µg/m³ Lethbridge, 15 August: 38.2 µg/m³, 4.0× its usual 9.5 Lethbridge, 16 August: 23.3 µg/m³ Lethbridge, 17 August: 5.3 µg/m³ Lethbridge, 18 August: 8.8 µg/m³ Lethbridge, 19 August: 6.5 µg/m³ Lethbridge, 20 August: 3.5 µg/m³ Lethbridge, 21 August: 3.4 µg/m³ Havre Havre, 11 August: 5.8 µg/m³ Havre, 12 August: 6.4 µg/m³ Havre, 13 August: 9.5 µg/m³ Havre, 14 August: 9.1 µg/m³ Havre, 15 August: 30.8 µg/m³, 4.7× its usual 6.6 Havre, 16 August: 36.8 µg/m³, 5.7× its usual 6.5 Havre, 17 August: 9.0 µg/m³ Havre, 18 August: 6.6 µg/m³ Havre, 19 August: 5.1 µg/m³ Havre, 20 August: 4.0 µg/m³ Havre, 21 August: 4.3 µg/m³ Prince George Prince George, 11 August: 47.3 µg/m³ Prince George, 12 August: 44.0 µg/m³ Prince George, 13 August: 18.7 µg/m³ Prince George, 14 August: 26.0 µg/m³ Prince George, 15 August: 30.6 µg/m³, 3.7× its usual 8.3 Prince George, 16 August: 18.5 µg/m³ Prince George, 17 August: 14.8 µg/m³ Prince George, 18 August: 15.8 µg/m³ Prince George, 19 August: 5.6 µg/m³ Prince George, 20 August: 8.2 µg/m³ Prince George, 21 August: 13.9 µg/m³ Edson Edson, 11 August: 12.0 µg/m³ Edson, 12 August: 12.4 µg/m³ Edson, 13 August: 18.7 µg/m³ Edson, 14 August: 15.7 µg/m³ Edson, 15 August: 25.6 µg/m³, 3.7× its usual 7.0 Edson, 16 August: 23.0 µg/m³ Edson, 17 August: 13.9 µg/m³ Edson, 18 August: 17.5 µg/m³ Edson, 19 August: 15.5 µg/m³ Edson, 20 August: 4.9 µg/m³ Edson, 21 August: 9.9 µg/m³ Estevan Estevan, 11 August: 16.5 µg/m³ Estevan, 12 August: 17.1 µg/m³ Estevan, 13 August: 8.5 µg/m³ Estevan, 14 August: no reading Estevan, 15 August: 20.2 µg/m³ Estevan, 16 August: 66.4 µg/m³, 5.5× its usual 12.0 Estevan, 17 August: 49.8 µg/m³, 4.1× its usual 12.0 Estevan, 18 August: 29.4 µg/m³, 2.4× its usual 12.1 Estevan, 19 August: 12.6 µg/m³ Estevan, 20 August: 15.3 µg/m³ Estevan, 21 August: 14.3 µg/m³ Miles City Miles City, 11 August: no reading Miles City, 12 August: no reading Miles City, 13 August: no reading Miles City, 14 August: 11.7 µg/m³ Miles City, 15 August: 24.0 µg/m³ Miles City, 16 August: 46.0 µg/m³, 5.3× its usual 8.6 Miles City, 17 August: 18.8 µg/m³ Miles City, 18 August: 17.1 µg/m³ Miles City, 19 August: 16.0 µg/m³ Miles City, 20 August: 9.1 µg/m³ Miles City, 21 August: 12.1 µg/m³ Glendive Glendive, 11 August: 6.0 µg/m³ Glendive, 12 August: 4.5 µg/m³ Glendive, 13 August: 6.2 µg/m³ Glendive, 14 August: 8.3 µg/m³ Glendive, 15 August: 27.1 µg/m³ Glendive, 16 August: 31.2 µg/m³, 4.5× its usual 7.0 Glendive, 17 August: 18.6 µg/m³ Glendive, 18 August: 13.7 µg/m³ Glendive, 19 August: 7.4 µg/m³ Glendive, 20 August: 6.0 µg/m³ Glendive, 21 August: 9.4 µg/m³ Lewistown Lewistown, 11 August: 8.0 µg/m³ Lewistown, 12 August: 9.9 µg/m³ Lewistown, 13 August: 10.4 µg/m³ Lewistown, 14 August: 11.4 µg/m³ Lewistown, 15 August: 15.8 µg/m³ Lewistown, 16 August: 31.1 µg/m³, 3.9× its usual 8.0 Lewistown, 17 August: 6.8 µg/m³ Lewistown, 18 August: 8.4 µg/m³ Lewistown, 19 August: 7.1 µg/m³ Lewistown, 20 August: 4.9 µg/m³ Lewistown, 21 August: 5.4 µg/m³ 11 Aug 13 15 17 19 21 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. Good 0–50
Moderate 51–100
Sensitive groups 101–150
Unhealthy 151–200
Very unhealthy 201–300
Hazardous 301+
Every city it reached
City Days Highest Usual Above usual
Fort Saskatchewan Alberta, Canada 5 14 August 10.1 17× Swift Current Saskatchewan, Canada 2 15 August 9.3 15× Edmonton Alberta, Canada 5 14 August 12.1 13× St. Albert Alberta, Canada 3 14 August 8.2 12× Drayton Valley Alberta, Canada 3 15 August 8.1 12× Fort McMurray Alberta, Canada 5 18 August 12.4 9.6× Grande Prairie Alberta, Canada 1 15 August 7.6 9.1× Medicine Hat Alberta, Canada 3 15 August 8.8 8.9× Saskatoon Saskatchewan, Canada 5 15 August 12.2 8.1× Red Deer Alberta, Canada 3 15 August 10.4 7.5× Airdrie Alberta, Canada 2 15 August 9.2 7.1× Sherwood Park Alberta, Canada 3 15 August 8.1 6.7× Havre Montana, United States 2 16 August 6.5 5.7× Estevan Saskatchewan, Canada 3 16 August 12.0 5.5× Regina Saskatchewan, Canada 4 15 August 11.0 5.5× Grand Centre Alberta, Canada 5 14 August 10.2 5.4× Miles City Montana, United States 1 16 August 8.6 5.3× Calgary Alberta, Canada 4 15 August 12.5 4.6× Glendive Montana, United States 1 16 August 7.0 4.5× Lethbridge Alberta, Canada 1 15 August 9.5 4.0× Lewistown Montana, United States 1 16 August 8.0 3.9× Prince George British Columbia, Canada 1 15 August 8.3 3.7× Edson Alberta, Canada 1 15 August 7.0 3.7×
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 Canada and the United States
Number 54 of 173 episodes in Canada and the United States since our records began, by cities reached.
Eastern United States and Canada, June and July 2023 343 Northern United States and Canada, July 2026 327 United States and Canada, July 2023 322 Eastern United States and Canada, May and June 2023 317 North-eastern United States and Canada, 29 July to 9 August 2025 292 Northern United States and Canada, May and June 2025 247 United States and Canada, June 2023 195 North-western United States and Canada, August 2023 176 North-western United States and Canada, 4 to 22 August 2026 151 Northern United States and Canada, July 2025 139 Northern United States and Canada, June 2025 134 North-western United States and Canada, July and August 2026 118 North-western Canada and United States, August 2024 23 Bars: cities reached; colour: the level of the episode's highest daily reading. All 173 .
Use this page SmogRank, North-western Canada and United States, August 2024: 23 cities with PM2.5 at twice their usual or more, 14 to 18 August 2024, smogrank.com/episodes/2024-08-north-western-canada-and-united-states (accessed 5 October 2026).
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You're welcome to reuse a single chart, image or figure with this citation and a link. Terms .
An episode is a run of days when many cities close to each other (four or more within 350 km on a day, 8 or more in all) each had a daily PM2.5 mean of at least 25 µg/m³ and at least 2 times their usual for that time of year. Found in our own measurements, not picked by hand. How we find episodes . Values are each city's daily mean of its own monitors; causes are the usual kinds for a pattern like this, not a confirmed source.
