SmogRank / Episodes / United States

Oregon, United States, September 2023

For 2 days, from 23 to 24 September 2023, 8 cities in the United States had PM2.5 at least twice their usual for the time of year. The worst reading was Ashland, Oregon, United States: 73.4 µg/m³ on 23 September, about 15× its usual 4.2.

No cause namedWe have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached8in 1 country
Days223 to 24 September 2023
Worst day23 September7 cities counted
Furthest above usual15×Ashland

Day by day

23 September 7 cities at twice their usual or more
AlbanyCorvallisSalemCoos BayDallasWoodburnCanbyMcMinnvilleMilwaukieTigardGreshamBeavertonPortlandHillsboroVancouverForest GroveOrchardsThe DallesPendletonEugeneRedmondBendAltamontGrants PassRoseburgMedfordAshland
20 Sep21222324252627
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

Grants PassGrants Pass, 20 September: 2.6 µg/m³, 0.5× usualGrants Pass, 21 September: 4.3 µg/m³, 0.9× usualGrants Pass, 22 September: 34.2 µg/m³, 6.8× usualGrants Pass, 23 September: 42.8 µg/m³, 8.6× usualGrants Pass, 24 September: 23.8 µg/m³, 4.8× usualGrants Pass, 25 September: 6.7 µg/m³, 1.3× usualGrants Pass, 26 September: 3.6 µg/m³, 0.7× usualGrants Pass, 27 September: 2.5 µg/m³, 0.5× usualAshlandAshland, 20 September: 3.3 µg/m³, 0.7× usualAshland, 21 September: 4.0 µg/m³, 0.8× usualAshland, 22 September: 16.9 µg/m³, 3.4× usualAshland, 23 September: 73.4 µg/m³, 15× usualAshland, 24 September: 37.0 µg/m³, 7.4× usualAshland, 25 September: 8.9 µg/m³, 1.8× usualAshland, 26 September: 4.1 µg/m³, 0.8× usualAshland, 27 September: 3.4 µg/m³, 0.7× usualMedfordMedford, 20 September: 3.8 µg/m³, 0.8× usualMedford, 21 September: 4.2 µg/m³, 0.8× usualMedford, 22 September: 21.9 µg/m³, 4.4× usualMedford, 23 September: 67.2 µg/m³, 13× usualMedford, 24 September: 45.4 µg/m³, 9.1× usualMedford, 25 September: 16.1 µg/m³, 3.2× usualMedford, 26 September: 6.6 µg/m³, 1.3× usualMedford, 27 September: 3.6 µg/m³, 0.7× usualRoseburgRoseburg, 20 September: 2.8 µg/m³, 0.6× usualRoseburg, 21 September: 4.5 µg/m³, 0.9× usualRoseburg, 22 September: 21.0 µg/m³, 4.2× usualRoseburg, 23 September: 43.5 µg/m³, 8.7× usualRoseburg, 24 September: 47.6 µg/m³, 9.5× usualRoseburg, 25 September: 6.8 µg/m³, 1.4× usualRoseburg, 26 September: 3.2 µg/m³, 0.6× usualRoseburg, 27 September: 2.9 µg/m³, 0.6× usualAltamontAltamont, 20 September: 5.0 µg/m³, 1.0× usualAltamont, 21 September: 5.4 µg/m³, 1.1× usualAltamont, 22 September: 13.8 µg/m³, 2.8× usualAltamont, 23 September: 34.8 µg/m³, 7.0× usualAltamont, 24 September: 29.5 µg/m³, 5.9× usualAltamont, 25 September: 5.6 µg/m³, 1.1× usualAltamont, 26 September: 2.8 µg/m³, 0.6× usualAltamont, 27 September: 3.5 µg/m³, 0.7× usualBendBend, 20 September: 7.9 µg/m³, 1.6× usualBend, 21 September: 5.8 µg/m³, 1.2× usualBend, 22 September: 4.8 µg/m³, 1.0× usualBend, 23 September: 34.1 µg/m³, 6.8× usualBend, 24 September: 33.6 µg/m³, 6.7× usualBend, 25 September: 6.3 µg/m³, 1.3× usualBend, 26 September: 2.1 µg/m³, 0.4× usualBend, 27 September: 2.5 µg/m³, 0.5× usualRedmondRedmond, 20 September: 9.6 µg/m³, 1.9× usualRedmond, 21 September: 8.4 µg/m³, 1.7× usualRedmond, 22 September: 7.9 µg/m³, 1.6× usualRedmond, 23 September: 29.3 µg/m³, 5.9× usualRedmond, 24 September: 31.4 µg/m³, 6.3× usualRedmond, 25 September: 9.8 µg/m³, 2.0× usualRedmond, 26 September: 2.7 µg/m³, 0.5× usualRedmond, 27 September: 3.4 µg/m³, 0.7× usualEugeneEugene, 20 September: 4.1 µg/m³, 0.8× usualEugene, 21 September: 8.8 µg/m³, 1.7× usualEugene, 22 September: 12.0 µg/m³, 2.3× usualEugene, 23 September: 9.2 µg/m³, 1.7× usualEugene, 24 September: 28.6 µg/m³, 5.4× usualEugene, 25 September: 13.7 µg/m³, 2.6× usualEugene, 26 September: 3.8 µg/m³, 0.7× usualEugene, 27 September: 3.3 µg/m³, 0.6× usual20 Sep21222324252627
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
AshlandOregon, United States2 73.423 September4.215×
MedfordOregon, United States2 67.223 September4.913×
RoseburgOregon, United States2 47.624 September3.99.5×
Grants PassOregon, United States1 42.823 September4.08.6×
AltamontOregon, United States2 34.823 September4.47.0×
BendOregon, United States2 34.123 September4.66.8×
RedmondOregon, United States2 31.424 September4.46.3×
EugeneOregon, United States1 28.624 September5.35.4×

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

Number 38 of 41 episodes in the United States since our records began, by cities reached.

Bars: cities reached; colour: the level of the episode's highest daily reading. All 41.

Use this page

SmogRank, Oregon, United States, September 2023: 8 cities with PM2.5 at twice their usual or more, 23 to 24 September 2023, smogrank.com/episodes/2023-09-oregon-united-states (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.