SmogRank / Episodes / Canada
Alberta, British Columbia and Saskatchewan, Canada, July 2023
For 5 days, from 9 to 13 July 2023, 17 cities in Canada had PM2.5 at least twice their usual for the time of year. The worst reading was Quesnel, British Columbia, Canada: 177.0 µg/m³ on 12 July, about 22× its usual 7.9. Readings stopped after 13 July, so this episode may have run longer.
No cause named We have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached 17 in 1 country
Days 5 9 to 13 July 2023
Worst day 13 July 12 cities counted
Furthest above usual 26× Prince George
Day by day
Play 13 July 12 cities at twice their usual or more
Sherwood Park Lethbridge Grand Centre Fort McMurray Vernon Kelowna Kamloops Prince Albert Whistler Squamish Regina Saskatoon Swift Current Medicine Hat St. Albert Drayton Valley Calgary Edmonton Red Deer Fort Saskatchewan Airdrie Williams Lake Edson Grande Prairie Quesnel Fort St. John Prince George 6 Jul 7 8 9 10 11 12 13 14 15 16 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 St. John Fort St. John, 6 July: 58.8 µg/m³ Fort St. John, 7 July: 59.4 µg/m³ Fort St. John, 8 July: 29.8 µg/m³ Fort St. John, 9 July: 84.9 µg/m³, 15× its usual 5.7 Fort St. John, 10 July: 146.0 µg/m³, 26× its usual 5.7 Fort St. John, 11 July: 68.6 µg/m³, 11× its usual 6.1 Fort St. John, 12 July: 45.2 µg/m³, 7.4× its usual 6.1 Fort St. John, 13 July: 33.6 µg/m³ Fort St. John, 14 July: no reading Fort St. John, 15 July: 82.2 µg/m³ Fort St. John, 16 July: 90.8 µg/m³ Quesnel Quesnel, 6 July: 23.9 µg/m³ Quesnel, 7 July: 25.0 µg/m³ Quesnel, 8 July: 15.6 µg/m³ Quesnel, 9 July: 37.2 µg/m³, 4.7× its usual 7.9 Quesnel, 10 July: 63.8 µg/m³, 8.1× its usual 7.9 Quesnel, 11 July: 68.8 µg/m³, 8.7× its usual 7.9 Quesnel, 12 July: 177.0 µg/m³, 22× its usual 7.9 Quesnel, 13 July: no reading Quesnel, 14 July: no reading Quesnel, 15 July: no reading Quesnel, 16 July: no reading Prince George Prince George, 6 July: 23.0 µg/m³ Prince George, 7 July: 26.1 µg/m³ Prince George, 8 July: 23.1 µg/m³ Prince George, 9 July: 36.9 µg/m³, 5.3× its usual 6.9 Prince George, 10 July: 40.3 µg/m³, 6.1× its usual 6.6 Prince George, 11 July: 82.6 µg/m³, 13× its usual 6.6 Prince George, 12 July: 170.0 µg/m³, 26× its usual 6.6 Prince George, 13 July: no reading Prince George, 14 July: no reading Prince George, 15 July: no reading Prince George, 16 July: no reading Grande Prairie Grande Prairie, 6 July: 32.7 µg/m³ Grande Prairie, 7 July: 19.2 µg/m³ Grande Prairie, 8 July: 26.8 µg/m³ Grande Prairie, 9 July: 29.5 µg/m³, 4.5× its usual 6.5 Grande Prairie, 10 July: 72.2 µg/m³, 11× its usual 6.6 Grande Prairie, 11 July: 66.2 µg/m³, 10× its usual 6.6 Grande Prairie, 12 July: 123.0 µg/m³, 19× its usual 6.6 Grande Prairie, 13 July: no reading Grande Prairie, 14 July: no reading Grande Prairie, 15 July: 94.9 µg/m³ Grande Prairie, 16 July: 154.0 µg/m³ Williams Lake Williams Lake, 6 July: 9.3 µg/m³ Williams Lake, 7 July: 9.2 µg/m³ Williams Lake, 8 July: 7.4 µg/m³ Williams Lake, 9 July: 7.7 µg/m³ Williams Lake, 10 July: 23.0 µg/m³ Williams Lake, 11 July: 12.2 µg/m³ Williams Lake, 12 July: 45.2 µg/m³, 9.0× its usual 4.5 Williams Lake, 13 July: 17.6 µg/m³ Williams Lake, 14 July: no reading Williams Lake, 15 July: 112.0 µg/m³ Williams Lake, 16 July: 18.0 µg/m³ Edson Edson, 6 July: 25.2 µg/m³ Edson, 7 July: 21.7 µg/m³ Edson, 8 July: 27.3 µg/m³ Edson, 9 July: 23.1 µg/m³ Edson, 10 July: 15.7 µg/m³ Edson, 11 July: 18.0 µg/m³ Edson, 12 July: 42.0 µg/m³, 5.8× its usual 7.3 Edson, 13 July: 72.3 µg/m³, 10× its usual 7.2 Edson, 14 July: no reading Edson, 15 July: no reading Edson, 16 July: no reading Drayton Valley Drayton Valley, 6 July: 21.9 µg/m³ Drayton Valley, 7 July: 21.5 µg/m³ Drayton Valley, 8 July: 31.8 µg/m³ Drayton Valley, 9 July: 21.7 µg/m³ Drayton Valley, 10 July: 16.4 µg/m³ Drayton Valley, 11 July: 9.4 µg/m³ Drayton Valley, 12 July: 36.9 µg/m³, 4.7× its usual 7.8 Drayton Valley, 13 July: 37.5 µg/m³, 4.7× its usual 7.9 Drayton Valley, 14 July: no reading Drayton Valley, 15 July: 60.8 µg/m³ Drayton Valley, 16 July: 45.2 µg/m³ Edmonton Edmonton, 6 July: 27.8 µg/m³ Edmonton, 7 July: 34.2 µg/m³ Edmonton, 8 July: 41.4 µg/m³ Edmonton, 9 July: 47.4 µg/m³ Edmonton, 10 July: 30.0 µg/m³ Edmonton, 11 July: 10.4 µg/m³ Edmonton, 12 July: 35.1 µg/m³, 2.9× its usual 11.9 Edmonton, 13 July: 75.9 µg/m³, 6.3× its usual 12.0 Edmonton, 14 July: no reading Edmonton, 15 July: 202.0 µg/m³ Edmonton, 16 July: 111.0 µg/m³ Red Deer Red Deer, 6 July: 22.5 µg/m³ Red Deer, 7 July: 22.1 µg/m³ Red Deer, 8 July: 21.3 µg/m³ Red Deer, 9 July: 26.6 µg/m³ Red Deer, 10 July: 22.7 µg/m³ Red Deer, 11 July: 7.6 µg/m³ Red Deer, 12 July: 32.2 µg/m³, 3.6× its usual 8.9 Red Deer, 13 July: 60.5 µg/m³, 6.6× its usual 9.1 Red Deer, 14 July: no reading Red Deer, 15 July: 91.9 µg/m³ Red Deer, 16 July: 57.7 µg/m³ Fort Saskatchewan Fort Saskatchewan, 6 July: 19.0 µg/m³ Fort Saskatchewan, 7 July: 27.3 µg/m³ Fort Saskatchewan, 8 July: 32.5 µg/m³ Fort Saskatchewan, 9 July: 40.1 µg/m³ Fort Saskatchewan, 10 July: 32.9 µg/m³ Fort Saskatchewan, 11 July: 6.7 µg/m³ Fort Saskatchewan, 12 July: 23.7 µg/m³ Fort Saskatchewan, 13 July: 72.3 µg/m³, 7.3× its usual 9.9 Fort Saskatchewan, 14 July: no reading Fort Saskatchewan, 15 July: 180.0 µg/m³ Fort Saskatchewan, 16 July: 102.0 µg/m³ Airdrie Airdrie, 6 July: no reading Airdrie, 7 July: 6.8 µg/m³ Airdrie, 8 July: 10.1 µg/m³ Airdrie, 9 July: 10.4 µg/m³ Airdrie, 10 July: 12.3 µg/m³ Airdrie, 11 July: 4.5 µg/m³ Airdrie, 12 July: 16.0 µg/m³ Airdrie, 13 July: 57.4 µg/m³, 7.9× its usual 7.3 Airdrie, 14 July: no reading Airdrie, 15 July: 40.8 µg/m³ Airdrie, 16 July: 41.1 µg/m³ Calgary Calgary, 6 July: no reading Calgary, 7 July: 13.3 µg/m³ Calgary, 8 July: 13.5 µg/m³ Calgary, 9 July: 18.6 µg/m³ Calgary, 10 July: 32.8 µg/m³ Calgary, 11 July: 8.9 µg/m³ Calgary, 12 July: 16.4 µg/m³ Calgary, 13 July: 55.3 µg/m³, 5.7× its usual 9.7 Calgary, 14 July: no reading Calgary, 15 July: 49.9 µg/m³ Calgary, 16 July: 47.1 µg/m³ Saskatoon Saskatoon, 6 July: no reading Saskatoon, 7 July: no reading Saskatoon, 8 July: no reading Saskatoon, 9 July: no reading Saskatoon, 10 July: no reading Saskatoon, 11 July: 6.1 µg/m³ Saskatoon, 12 July: 9.3 µg/m³ Saskatoon, 13 July: 39.1 µg/m³, 3.2× its usual 12.2 Saskatoon, 14 July: no reading Saskatoon, 15 July: 46.3 µg/m³ Saskatoon, 16 July: 19.5 µg/m³ St. Albert St. Albert, 6 July: 14.3 µg/m³ St. Albert, 7 July: 17.0 µg/m³ St. Albert, 8 July: 25.8 µg/m³ St. Albert, 9 July: 26.9 µg/m³ St. Albert, 10 July: 15.2 µg/m³ St. Albert, 11 July: 4.8 µg/m³ St. Albert, 12 July: 21.9 µg/m³ St. Albert, 13 July: 38.4 µg/m³, 4.5× its usual 8.5 St. Albert, 14 July: no reading St. Albert, 15 July: 112.0 µg/m³ St. Albert, 16 July: 50.3 µg/m³ Swift Current Swift Current, 6 July: no reading Swift Current, 7 July: no reading Swift Current, 8 July: no reading Swift Current, 9 July: no reading Swift Current, 10 July: no reading Swift Current, 11 July: 5.5 µg/m³ Swift Current, 12 July: 6.4 µg/m³ Swift Current, 13 July: 29.6 µg/m³, 3.6× its usual 8.2 Swift Current, 14 July: no reading Swift Current, 15 July: 159.0 µg/m³ Swift Current, 16 July: 65.2 µg/m³ Medicine Hat Medicine Hat, 6 July: 10.3 µg/m³ Medicine Hat, 7 July: 13.4 µg/m³ Medicine Hat, 8 July: 9.5 µg/m³ Medicine Hat, 9 July: 12.7 µg/m³ Medicine Hat, 10 July: 22.8 µg/m³ Medicine Hat, 11 July: 5.8 µg/m³ Medicine Hat, 12 July: 9.0 µg/m³ Medicine Hat, 13 July: 29.1 µg/m³, 4.3× its usual 6.7 Medicine Hat, 14 July: no reading Medicine Hat, 15 July: 70.7 µg/m³ Medicine Hat, 16 July: 92.0 µg/m³ Regina Regina, 6 July: no reading Regina, 7 July: no reading Regina, 8 July: no reading Regina, 9 July: no reading Regina, 10 July: no reading Regina, 11 July: 4.8 µg/m³ Regina, 12 July: 6.4 µg/m³ Regina, 13 July: 25.3 µg/m³, 2.2× its usual 11.6 Regina, 14 July: no reading Regina, 15 July: 32.9 µg/m³ Regina, 16 July: 10.9 µg/m³ 6 Jul 8 10 12 14 16 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
Prince George British Columbia, Canada 4 12 July 6.6 26× Fort St. John British Columbia, Canada 4 10 July 5.7 26× Quesnel British Columbia, Canada 4 12 July 7.9 22× Grande Prairie Alberta, Canada 4 12 July 6.6 19× Edson Alberta, Canada 2 13 July 7.2 10× Williams Lake British Columbia, Canada 1 12 July 4.5 9.0× Airdrie Alberta, Canada 1 13 July 7.3 7.9× Fort Saskatchewan Alberta, Canada 1 13 July 9.9 7.3× Red Deer Alberta, Canada 2 13 July 9.1 6.6× Edmonton Alberta, Canada 2 13 July 12.0 6.3× Calgary Alberta, Canada 1 13 July 9.7 5.7× Drayton Valley Alberta, Canada 2 13 July 7.9 4.7× St. Albert Alberta, Canada 1 13 July 8.5 4.5× Medicine Hat Alberta, Canada 1 13 July 6.7 4.3× Swift Current Saskatchewan, Canada 1 13 July 8.2 3.6× Saskatoon Saskatchewan, Canada 1 13 July 12.2 3.2× Regina Saskatchewan, Canada 1 13 July 11.6 2.2×
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
Number 21 of 43 episodes in Canada since our records began, by cities reached.
North-western United States and Canada, August 2023 176 Northern United States and Canada, July 2025 139 North-western United States and Canada, July and August 2026 118 North-western United States and Canada, August and September 2025 94 North-western United States and Canada, July 2024 92 Northern United States and Canada, May 2023 83 Northern United States and Canada, August and September 2023 82 North-western United States and Canada, May 2023 63 North-western Canada and United States, September 2025 57 North-eastern United States and Canada, March 2026 40 North-western Canada and United States, June 2025 28 South-eastern Canada and United States, December 2024 27 Alberta, British Columbia and Saskatchewan, Canada, July 2023 17 Bars: cities reached; colour: the level of the episode's highest daily reading. All 43 .
Use this page SmogRank, Alberta, British Columbia and Saskatchewan, Canada, July 2023: 17 cities with PM2.5 at twice their usual or more, 9 to 13 July 2023, smogrank.com/episodes/2023-07-alberta-british-columbia-and-saskatchewan-canada (accessed 5 October 2026).
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You're welcome to reuse a single chart, image or figure with this citation and a link. Terms .
An episode is a run of days when many cities close to each other (four or more within 350 km on a day, 8 or more in all) each had a daily PM2.5 mean of at least 25 µg/m³ and at least 2 times their usual for that time of year. Found in our own measurements, not picked by hand. How we find episodes . Values are each city's daily mean of its own monitors; causes are the usual kinds for a pattern like this, not a confirmed source.
