SmogRank / Episodes / United States
North-western United States and Canada, August 2024
For 3 days, from 1 to 3 August 2024, 16 cities in the United States and Canada had PM2.5 at least twice their usual for the time of year. The worst reading was Chico, California, United States: 81.2 µg/m³ on 2 August, about 11× its usual 7.1. Ended 3 August.
No cause named We have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached 16 in 2 countries
Days 3 1 to 3 August 2024
Worst day 1 August 7 cities counted
Furthest above usual 11× Chico
Day by day
Play 1 August 7 cities at twice their usual or more
Pendleton Hermiston Prineville Baker City Tri-Cities Madras Redmond Walla Walla The Dalles Hood River Weiser Moses Lake Ontario Ellensburg Quincy Ephrata Wenatchee Lewiston Nampa Pullman Gresham Meridian Moscow Garden City Sweet Home Milwaukie Canby Stayton Portland Silverton Vancouver Salmon Creek North Portland Tigard Woodburn Beaverton Airway Heights Ridgefield Spokane Salem Hillsboro Albany Eugene Mead Forest Grove McMinnville Longview Corvallis Auburn Dallas Parkland Renton Tacoma Coeur d'Alene Bellevue Chehalis Centralia White Center Roseburg Seattle Lacey Green Shoreline Yreka Picnic Point-North Lynnwood Bremerton Marysville Grants Pass Shelton Sandpoint Mount Vernon Port Townsend Penticton Oak Harbor Coos Bay Spanish Springs Aberdeen Redding Anacortes Reno Bellingham Hope Agassiz Chilliwack Red Bluff Kelowna Abbotsford Lynden Port Angeles Creston Twin Falls Mission Carson City Victoria Brookings Langley Langford Vernon Strawberry Hill South Lake Tahoe Gridley Port Coquitlam Coquitlam Delta Willows Burnaby Missoula Richmond Yuba City North Auburn Vancouver North Vancouver Duncan Colusa Burley North Cowichan West Vancouver Gibsons Squamish Harewood Nanaimo Columbia Falls Whistler Ukiah Port Alberni Courtenay Spokane Valley La Grande Bend Sunnyside Cranbrook Paradise Castlegar Ashland Medford Talent Cottage Grove Prosser Toppenish Yakima Altamont Chico 29 Jul 30 31 1 Aug 2 3 4 5 6 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
Altamont Altamont, 29 July: 11.1 µg/m³ Altamont, 30 July: 2.5 µg/m³ Altamont, 31 July: 17.8 µg/m³ Altamont, 1 August: 58.8 µg/m³, 8.3× its usual 7.1 Altamont, 2 August: 28.2 µg/m³, 4.0× its usual 7.1 Altamont, 3 August: 20.6 µg/m³ Altamont, 4 August: 10.9 µg/m³ Altamont, 5 August: 13.4 µg/m³ Altamont, 6 August: 22.9 µg/m³ Medford Medford, 29 July: 8.3 µg/m³ Medford, 30 July: 2.3 µg/m³ Medford, 31 July: 12.9 µg/m³ Medford, 1 August: 32.7 µg/m³, 5.5× its usual 6.0 Medford, 2 August: 15.1 µg/m³ Medford, 3 August: 21.5 µg/m³ Medford, 4 August: 19.8 µg/m³ Medford, 5 August: 17.0 µg/m³ Medford, 6 August: 13.6 µg/m³ Chico Chico, 29 July: 11.9 µg/m³ Chico, 30 July: 17.5 µg/m³ Chico, 31 July: 16.1 µg/m³ Chico, 1 August: 31.8 µg/m³, 4.4× its usual 7.3 Chico, 2 August: 81.2 µg/m³, 11× its usual 7.1 Chico, 3 August: 22.8 µg/m³ Chico, 4 August: 16.2 µg/m³ Chico, 5 August: 11.2 µg/m³ Chico, 6 August: 12.5 µg/m³ Cottage Grove Cottage Grove, 29 July: 2.9 µg/m³ Cottage Grove, 30 July: 1.2 µg/m³ Cottage Grove, 31 July: 8.3 µg/m³ Cottage Grove, 1 August: 31.6 µg/m³, 6.3× its usual 3.7 Cottage Grove, 2 August: 6.9 µg/m³ Cottage Grove, 3 August: 4.7 µg/m³ Cottage Grove, 4 August: 22.1 µg/m³ Cottage Grove, 5 August: 5.1 µg/m³ Cottage Grove, 6 August: 5.2 µg/m³ Talent Talent, 29 July: 7.5 µg/m³ Talent, 30 July: no reading Talent, 31 July: 7.9 µg/m³ Talent, 1 August: 30.8 µg/m³, 5.6× its usual 5.5 Talent, 2 August: 13.8 µg/m³ Talent, 3 August: 18.9 µg/m³ Talent, 4 August: 16.6 µg/m³ Talent, 5 August: 16.3 µg/m³ Talent, 6 August: 10.5 µg/m³ Ashland Ashland, 29 July: 8.3 µg/m³ Ashland, 30 July: 2.3 µg/m³ Ashland, 31 July: 8.4 µg/m³ Ashland, 1 August: 29.3 µg/m³, 4.7× its usual 6.2 Ashland, 2 August: 13.8 µg/m³ Ashland, 3 August: 20.6 µg/m³ Ashland, 4 August: 16.4 µg/m³ Ashland, 5 August: 18.5 µg/m³ Ashland, 6 August: 11.8 µg/m³ Paradise Paradise, 29 July: 14.6 µg/m³ Paradise, 30 July: 9.5 µg/m³ Paradise, 31 July: 132.0 µg/m³ Paradise, 1 August: 25.0 µg/m³, 4.0× its usual 6.2 Paradise, 2 August: 14.7 µg/m³ Paradise, 3 August: 12.7 µg/m³ Paradise, 4 August: 8.5 µg/m³ Paradise, 5 August: 6.9 µg/m³ Paradise, 6 August: 6.5 µg/m³ Toppenish Toppenish, 29 July: 33.9 µg/m³ Toppenish, 30 July: 2.3 µg/m³ Toppenish, 31 July: 12.4 µg/m³ Toppenish, 1 August: 16.3 µg/m³ Toppenish, 2 August: 38.4 µg/m³, 5.5× its usual 7.0 Toppenish, 3 August: 50.9 µg/m³, 7.2× its usual 7.1 Toppenish, 4 August: 27.9 µg/m³ Toppenish, 5 August: 23.7 µg/m³ Toppenish, 6 August: 18.4 µg/m³ Yakima Yakima, 29 July: 40.1 µg/m³ Yakima, 30 July: 5.4 µg/m³ Yakima, 31 July: 8.6 µg/m³ Yakima, 1 August: 13.2 µg/m³ Yakima, 2 August: 38.0 µg/m³, 7.3× its usual 5.2 Yakima, 3 August: 19.9 µg/m³ Yakima, 4 August: 11.9 µg/m³ Yakima, 5 August: 14.2 µg/m³ Yakima, 6 August: 6.8 µg/m³ La Grande La Grande, 29 July: 23.9 µg/m³ La Grande, 30 July: 11.7 µg/m³ La Grande, 31 July: 8.0 µg/m³ La Grande, 1 August: 20.0 µg/m³ La Grande, 2 August: 28.0 µg/m³, 3.3× its usual 8.4 La Grande, 3 August: 14.6 µg/m³ La Grande, 4 August: 10.3 µg/m³ La Grande, 5 August: 13.2 µg/m³ La Grande, 6 August: 12.0 µg/m³ Bend Bend, 29 July: 68.9 µg/m³ Bend, 30 July: 19.2 µg/m³ Bend, 31 July: 26.9 µg/m³ Bend, 1 August: 13.7 µg/m³ Bend, 2 August: 27.4 µg/m³, 3.4× its usual 8.1 Bend, 3 August: 16.5 µg/m³ Bend, 4 August: 10.0 µg/m³ Bend, 5 August: 27.2 µg/m³ Bend, 6 August: 31.3 µg/m³ Sunnyside Sunnyside, 29 July: 22.2 µg/m³ Sunnyside, 30 July: 7.5 µg/m³ Sunnyside, 31 July: 6.7 µg/m³ Sunnyside, 1 August: 12.6 µg/m³ Sunnyside, 2 August: 25.9 µg/m³, 3.6× its usual 7.2 Sunnyside, 3 August: 27.1 µg/m³, 3.7× its usual 7.4 Sunnyside, 4 August: 18.5 µg/m³ Sunnyside, 5 August: 14.7 µg/m³ Sunnyside, 6 August: 9.1 µg/m³ Prosser Prosser, 29 July: 12.8 µg/m³ Prosser, 30 July: 2.8 µg/m³ Prosser, 31 July: 6.3 µg/m³ Prosser, 1 August: 11.1 µg/m³ Prosser, 2 August: 22.7 µg/m³ Prosser, 3 August: 47.1 µg/m³, 7.0× its usual 6.7 Prosser, 4 August: 18.0 µg/m³ Prosser, 5 August: 12.8 µg/m³ Prosser, 6 August: 14.8 µg/m³ Castlegar Castlegar, 29 July: 38.6 µg/m³ Castlegar, 30 July: 11.5 µg/m³ Castlegar, 31 July: 9.7 µg/m³ Castlegar, 1 August: 6.9 µg/m³ Castlegar, 2 August: 23.1 µg/m³ Castlegar, 3 August: 40.3 µg/m³, 4.6× its usual 8.8 Castlegar, 4 August: 20.7 µg/m³ Castlegar, 5 August: 16.9 µg/m³ Castlegar, 6 August: 22.2 µg/m³ Cranbrook Cranbrook, 29 July: 16.9 µg/m³ Cranbrook, 30 July: 5.9 µg/m³ Cranbrook, 31 July: 4.2 µg/m³ Cranbrook, 1 August: 10.0 µg/m³ Cranbrook, 2 August: 17.9 µg/m³ Cranbrook, 3 August: 32.3 µg/m³, 3.7× its usual 8.7 Cranbrook, 4 August: 27.5 µg/m³ Cranbrook, 5 August: 14.0 µg/m³ Cranbrook, 6 August: 12.3 µg/m³ Spokane Valley Spokane Valley, 29 July: 15.1 µg/m³ Spokane Valley, 30 July: 4.0 µg/m³ Spokane Valley, 31 July: 3.3 µg/m³ Spokane Valley, 1 August: 7.0 µg/m³ Spokane Valley, 2 August: 9.0 µg/m³ Spokane Valley, 3 August: 25.0 µg/m³, 3.0× its usual 8.4 Spokane Valley, 4 August: 19.6 µg/m³ Spokane Valley, 5 August: 10.4 µg/m³ Spokane Valley, 6 August: 10.2 µg/m³ 29 Jul 30 31 1 Aug 2 3 4 5 6 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
Chico California, United States 2 2 August 7.1 11× Altamont Oregon, United States 2 1 August 7.1 8.3× Yakima Washington, United States 1 2 August 5.2 7.3× Toppenish Washington, United States 2 3 August 7.1 7.2× Prosser Washington, United States 1 3 August 6.7 7.0× Cottage Grove Oregon, United States 1 1 August 3.7 6.3× Talent Oregon, United States 1 1 August 5.5 5.6× Medford Oregon, United States 1 1 August 6.0 5.5× Ashland Oregon, United States 1 1 August 6.2 4.7× Castlegar British Columbia, Canada 1 3 August 8.8 4.6× Paradise California, United States 1 1 August 6.2 4.0× Cranbrook British Columbia, Canada 1 3 August 8.7 3.7× Sunnyside Washington, United States 2 3 August 7.4 3.7× Bend Oregon, United States 1 2 August 8.1 3.4× La Grande Oregon, United States 1 2 August 8.4 3.3× Spokane Valley Washington, United States 1 3 August 8.4 3.0×
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 90 of 173 episodes in the United States and Canada 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 United States and Canada, August 2024 16 Bars: cities reached; colour: the level of the episode's highest daily reading. All 173 .
Use this page SmogRank, North-western United States and Canada, August 2024: 16 cities with PM2.5 at twice their usual or more, 1 to 3 August 2024, smogrank.com/episodes/2024-08-north-western-united-states-and-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.
