Worst air pollution Diamond Bar, today and tomorrow
Today (15 July): Air quality in Diamond Bar is fair. AQI, PM10, and O3 are fair; PM2.5, NO2, SO2, CO, HCHO, and PM1 are good. Pollution peaks around 8:00 AM (O3: 31.2/100).
Tomorrow (16 July 2026): Air quality in Diamond Bar is fair. All pollutants stay as today. Pollution peaks around 9:00 AM (O3: 29.9/100). Airmine updates local air quality forecasts four times daily.
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Developed with support from the European Space Agency (ESA)’s Business Applications and Space Solutions (BASS) team
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Diamond Bar's air quality reflects the Pomona Valley's enclosed position in the eastern Los Angeles basin, with vehicle emissions from SR-57 and SR-60 the primary local sources. The basin inversion affects all of the eastern Los Angeles-San Gabriel Valley corridor, while Diamond Bar's hillside position provides marginally better topographic variation than the flat valley floor, though the persistent basin inversion continues to concentrate ozone and PM2.5 and the valley position tracks at consistently elevated suburban readings throughout the year.
Today - 15 July | Pollution peaks at 08:00
AQI:
Fair
31.2/100
PM2.5 (fine particles):
Good
16.2/100
PM10 (coarse particles):
Fair
24.7/100
NO2 (nitrogen dioxide):
Good
0.5/100
O3 (ozone):
Fair
31.2/100
SO2 (sulfur dioxide):
Good
0.8/100
CO (carbon monoxide):
Good
0.0/100
HCHO (formaldehyde):
Good
0.9/100
PM1 (ultrafine particles):
Good
2.8/100
Levels show the poorest local air quality during the day
Tomorrow - 16 July | Pollution peaks at 09:00
AQI:
Fair
29.9/100
PM2.5 (fine particles):
Good
15.0/100
PM10 (coarse particles):
Fair
25.4/100
NO2 (nitrogen dioxide):
Good
0.9/100
O3 (ozone):
Fair
29.9/100
SO2 (sulfur dioxide):
Good
1.5/100
CO (carbon monoxide):
Good
0.0/100
HCHO (formaldehyde):
Good
1.0/100
PM1 (ultrafine particles):
Good
3.0/100
Pollen forecast in Diamond Bar
View pollen forecastFrequently Asked Questions
Is air quality bad in Diamond Bar right now?
On 15 July 2026, overall air quality in Diamond Bar is fair. AQI is the main air quality indicator at 31.2/100. Pollution peaks around 8:00 AM (O3: 31.2/100).
Will air quality be worse tomorrow in Diamond Bar?
On 16 July 2026, air quality conditions in Diamond Bar will be similar to today, with AQI forecast at fair at 29.9/100. Pollution peaks around 9:00 AM (O3: 29.9/100).
When is air pollution at its worst in Diamond Bar?
Diamond Bar experiences a distinct seasonal swing in air quality — winter typically brings the cleanest stretch, once occasional rain clears the basin, whereas summer sunshine and heat drive some of the worst ozone readings in the country. Coastal breezes offer some relief compared to inland valley locations that see heavier smog buildup.
Are air quality levels in Diamond Bar based on measurements or forecasts?
It is forecasts derived by downscaling forecasts provided by EU’s Copernicus Atmosphere Monitoring Service (CAMS) by taking into account local conditions such as traffic patterns. CAMS bases its forecast on satellite measurements of particles and chemical compounds in the atmosphere. Airmine’s services were developed with support from the European Space Agency (ESA)’s Business Applications and Space Solutions (BASS) team.
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Data provided by Airmine — Last update: 16 July 2026 at 10:33 CEST (Data is updated four times daily.)
This forecast is produced independently using Airmine's own atmospheric data and models.
Unless explicitly made clear, the content on this site has not been paid for by external organisations and is Airmine's sole responsibility.
For long term forecasts and maps, see the Airmine app