SmogRank / Episodes / United States

Idaho and Utah, United States, August 2024

For 2 days, from 8 to 9 August 2024, 10 cities in the United States had PM2.5 at least twice their usual for the time of year. The worst reading was Boise, Idaho, United States: 99.9 µg/m³ on 8 August, about 14× its usual 7.3.

No cause namedWe have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached10in 1 country
Days28 to 9 August 2024
Worst day8 August9 cities counted
Furthest above usual14×Boise

Day by day

8 August 9 cities at twice their usual or more
MagnaIdaho FallsBountifulHerrimanWest JordanCondaHighlandRexburgOremSpanish ForkRock SpringsSpanish SpringsMillcreekWest Valley CitySalt Lake CityTooelePocatelloTwin FallsNorth OgdenNampaMeridianBoise
5 Aug6789101112
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

BoiseBoise, 5 August: 14.5 µg/m³, 2.0× usualBoise, 6 August: 23.0 µg/m³, 3.2× usualBoise, 7 August: 34.5 µg/m³, 4.7× usualBoise, 8 August: 99.9 µg/m³, 14× usualBoise, 9 August: 57.3 µg/m³, 7.8× usualBoise, 10 August: 23.5 µg/m³, 3.2× usualBoise, 11 August: 19.7 µg/m³, 2.7× usualBoise, 12 August: 19.5 µg/m³, 2.7× usualTwin FallsTwin Falls, 5 August: 13.3 µg/m³, 2.0× usualTwin Falls, 6 August: 14.0 µg/m³, 2.1× usualTwin Falls, 7 August: 31.4 µg/m³, 4.8× usualTwin Falls, 8 August: 30.3 µg/m³, 4.6× usualTwin Falls, 9 August: 21.5 µg/m³, 3.3× usualTwin Falls, 10 August: 20.3 µg/m³, 3.1× usualTwin Falls, 11 August: 14.0 µg/m³, 2.1× usualTwin Falls, 12 August: 7.8 µg/m³, 1.2× usualPocatelloPocatello, 5 August: 15.4 µg/m³, 2.7× usualPocatello, 6 August: 7.3 µg/m³, 1.3× usualPocatello, 7 August: 29.5 µg/m³, 5.1× usualPocatello, 8 August: 23.9 µg/m³, 4.1× usualPocatello, 9 August: 26.8 µg/m³, 4.6× usualPocatello, 10 August: 17.4 µg/m³, 3.0× usualPocatello, 11 August: 13.9 µg/m³, 2.4× usualPocatello, 12 August: 9.1 µg/m³, 1.6× usualMeridianMeridian, 5 August: 16.5 µg/m³, 2.0× usualMeridian, 6 August: 19.0 µg/m³, 2.3× usualMeridian, 7 August: 24.2 µg/m³, 2.9× usualMeridian, 8 August: 74.4 µg/m³, 9.0× usualMeridian, 9 August: 51.9 µg/m³, 6.3× usualMeridian, 10 August: 24.0 µg/m³, 2.9× usualMeridian, 11 August: 18.4 µg/m³, 2.2× usualMeridian, 12 August: 22.4 µg/m³, 2.7× usualNampaNampa, 5 August: 15.3 µg/m³, 1.6× usualNampa, 6 August: 17.3 µg/m³, 1.8× usualNampa, 7 August: 17.7 µg/m³, 1.8× usualNampa, 8 August: 63.5 µg/m³, 6.5× usualNampa, 9 August: 55.0 µg/m³, 5.7× usualNampa, 10 August: 22.0 µg/m³, 2.3× usualNampa, 11 August: 16.5 µg/m³, 1.7× usualNampa, 12 August: 21.0 µg/m³, 2.2× usualNorth OgdenNorth Ogden, 5 August: 11.0 µg/m³, 1.7× usualNorth Ogden, 6 August: 5.2 µg/m³, 0.8× usualNorth Ogden, 7 August: 17.4 µg/m³, 2.6× usualNorth Ogden, 8 August: 30.7 µg/m³, 4.7× usualNorth Ogden, 9 August: 16.8 µg/m³, 2.5× usualNorth Ogden, 10 August: 6.9 µg/m³, 1.0× usualNorth Ogden, 11 August: 14.0 µg/m³, 2.1× usualNorth Ogden, 12 August: 4.1 µg/m³, 0.6× usualMillcreekMillcreek, 5 August: 13.1 µg/m³, 1.4× usualMillcreek, 6 August: 10.2 µg/m³, 1.1× usualMillcreek, 7 August: 19.2 µg/m³, 2.1× usualMillcreek, 8 August: 29.0 µg/m³, 3.2× usualMillcreek, 9 August: 11.3 µg/m³, 1.2× usualMillcreek, 10 August: 8.9 µg/m³, 1.0× usualMillcreek, 11 August: 7.7 µg/m³, 0.8× usualMillcreek, 12 August: 9.5 µg/m³, 1.0× usualTooeleTooele, 5 August: 16.8 µg/m³, 2.4× usualTooele, 6 August: 11.0 µg/m³, 1.5× usualTooele, 7 August: 17.5 µg/m³, 2.5× usualTooele, 8 August: 28.3 µg/m³, 4.0× usualTooele, 9 August: 10.2 µg/m³, 1.4× usualTooele, 10 August: 7.5 µg/m³, 1.1× usualTooele, 11 August: 17.0 µg/m³, 2.4× usualTooele, 12 August: 5.3 µg/m³, 0.7× usualWest Valley CityWest Valley City, 5 August: 8.0 µg/m³, 1.1× usualWest Valley City, 6 August: 8.2 µg/m³, 1.1× usualWest Valley City, 7 August: 15.3 µg/m³, 2.0× usualWest Valley City, 8 August: 27.8 µg/m³, 3.7× usualWest Valley City, 9 August: 9.2 µg/m³, 1.2× usualWest Valley City, 10 August: 7.3 µg/m³, 1.0× usualWest Valley City, 11 August: 9.6 µg/m³, 1.3× usualWest Valley City, 12 August: 4.4 µg/m³, 0.6× usualSalt Lake CitySalt Lake City, 5 August: 9.0 µg/m³, 1.2× usualSalt Lake City, 6 August: 7.5 µg/m³, 1.0× usualSalt Lake City, 7 August: 14.3 µg/m³, 1.9× usualSalt Lake City, 8 August: 27.3 µg/m³, 3.7× usualSalt Lake City, 9 August: 9.1 µg/m³, 1.2× usualSalt Lake City, 10 August: 6.3 µg/m³, 0.9× usualSalt Lake City, 11 August: 8.4 µg/m³, 1.1× usualSalt Lake City, 12 August: 4.5 µg/m³, 0.6× usual5 Aug6789101112
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
BoiseIdaho, United States2 99.98 August7.314×
MeridianIdaho, United States2 74.48 August8.39.0×
NampaIdaho, United States2 63.58 August9.76.5×
PocatelloIdaho, United States1 29.57 August5.85.1×
Twin FallsIdaho, United States1 31.47 August6.64.8×
North OgdenUtah, United States1 30.78 August6.64.7×
TooeleUtah, United States1 28.38 August7.14.0×
West Valley CityUtah, United States1 27.88 August7.53.7×
Salt Lake CityUtah, United States1 27.38 August7.43.7×
MillcreekUtah, United States1 29.08 August9.13.2×

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 95 of 131 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 131.

Use this page

SmogRank, Idaho and Utah, United States, August 2024: 10 cities with PM2.5 at twice their usual or more, 8 to 9 August 2024, smogrank.com/episodes/2024-08-idaho-and-utah-united-states (accessed 3 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.