SmogRank / Episodes / United States

Nevada, United States, September 2024

For 1 day, on 11 September 2024, 8 cities in the United States had PM2.5 at least twice their usual for the time of year. The worst reading was Boulder City, Nevada, United States: 85.1 µg/m³ on 11 September, about 17× its usual 3.2.

No cause namedWe have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached8in 1 country
Days111 September 2024
Worst day11 September8 cities counted
Furthest above usual17×Boulder City

Day by day

11 September 8 cities at twice their usual or more
Cedar CityRidgecrestVictorvilleLancasterGlendoraLa Crescenta-MontroseBurbankPortervilleSanta ClaritaBakersfieldVisaliaSimi ValleyAgouraFillmoreThousand OaksOxnardHurricaneSummerlin SouthSpring ValleyLas VegasEnterpriseMesquiteHendersonBoulder City
8 Sep91011121314
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

Boulder CityBoulder City, 8 September: 5.4 µg/m³, 1.1× usualBoulder City, 9 September: 4.8 µg/m³, 1.0× usualBoulder City, 10 September: 13.4 µg/m³, 2.7× usualBoulder City, 11 September: 85.1 µg/m³, 17× usualBoulder City, 12 September: 18.7 µg/m³, 3.7× usualBoulder City, 13 September: 9.7 µg/m³, 1.9× usualBoulder City, 14 September: 3.8 µg/m³, 0.8× usualHendersonHenderson, 8 September: 6.5 µg/m³, 1.3× usualHenderson, 9 September: 7.1 µg/m³, 1.4× usualHenderson, 10 September: 15.1 µg/m³, 3.0× usualHenderson, 11 September: 71.4 µg/m³, 14× usualHenderson, 12 September: 23.7 µg/m³, 4.7× usualHenderson, 13 September: 10.2 µg/m³, 2.0× usualHenderson, 14 September: 4.7 µg/m³, 0.9× usualMesquiteMesquite, 8 September: 6.9 µg/m³, 1.4× usualMesquite, 9 September: 6.3 µg/m³, 1.3× usualMesquite, 10 September: 9.1 µg/m³, 1.8× usualMesquite, 11 September: 68.8 µg/m³, 14× usualMesquite, 12 September: 14.7 µg/m³, 2.9× usualMesquite, 13 September: 10.1 µg/m³, 2.0× usualMesquite, 14 September: 8.0 µg/m³, 1.6× usualEnterpriseEnterprise, 8 September: 5.9 µg/m³, 1.2× usualEnterprise, 9 September: 6.7 µg/m³, 1.3× usualEnterprise, 10 September: 12.5 µg/m³, 2.5× usualEnterprise, 11 September: 52.0 µg/m³, 10× usualEnterprise, 12 September: 20.2 µg/m³, 4.0× usualEnterprise, 13 September: 9.9 µg/m³, 2.0× usualEnterprise, 14 September: 4.1 µg/m³, 0.8× usualLas VegasLas Vegas, 8 September: 6.8 µg/m³, 1.3× usualLas Vegas, 9 September: 8.5 µg/m³, 1.6× usualLas Vegas, 10 September: 15.6 µg/m³, 3.0× usualLas Vegas, 11 September: 51.4 µg/m³, 9.9× usualLas Vegas, 12 September: 24.2 µg/m³, 4.7× usualLas Vegas, 13 September: 10.4 µg/m³, 2.0× usualLas Vegas, 14 September: 7.6 µg/m³, 1.5× usualSpring ValleySpring Valley, 8 September: 6.5 µg/m³, 1.3× usualSpring Valley, 9 September: 7.6 µg/m³, 1.5× usualSpring Valley, 10 September: 13.9 µg/m³, 2.8× usualSpring Valley, 11 September: 43.5 µg/m³, 8.7× usualSpring Valley, 12 September: 21.4 µg/m³, 4.3× usualSpring Valley, 13 September: 11.7 µg/m³, 2.3× usualSpring Valley, 14 September: 5.7 µg/m³, 1.1× usualSummerlin SouthSummerlin South, 8 September: 9.8 µg/m³, 2.0× usualSummerlin South, 9 September: 10.0 µg/m³, 2.0× usualSummerlin South, 10 September: 16.8 µg/m³, 3.4× usualSummerlin South, 11 September: 34.3 µg/m³, 6.9× usualSummerlin South, 12 September: 25.3 µg/m³, 5.1× usualSummerlin South, 13 September: 14.0 µg/m³, 2.8× usualSummerlin South, 14 September: 7.0 µg/m³, 1.4× usualHurricaneHurricane, 8 September: 4.9 µg/m³, 1.0× usualHurricane, 9 September: 4.8 µg/m³, 1.0× usualHurricane, 10 September: 2.8 µg/m³, 0.6× usualHurricane, 11 September: 31.6 µg/m³, 6.3× usualHurricane, 12 September: 6.9 µg/m³, 1.4× usualHurricane, 13 September: 10.5 µg/m³, 2.1× usualHurricane, 14 September: 8.4 µg/m³, 1.7× usual8 Sep91011121314
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
Boulder CityNevada, United States1 85.111 September3.217×
HendersonNevada, United States1 71.411 September4.014×
MesquiteNevada, United States1 68.811 September3.314×
EnterpriseNevada, United States1 52.011 September4.010×
Las VegasNevada, United States1 51.411 September5.29.9×
Spring ValleyNevada, United States1 43.511 September4.18.7×
Summerlin SouthNevada, United States1 34.311 September4.16.9×
HurricaneUtah, United States1 31.611 September3.96.3×

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 123 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, Nevada, United States, September 2024: 8 cities with PM2.5 at twice their usual or more, 11 September 2024, smogrank.com/episodes/2024-09-nevada-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.