Worst air pollution St. Johns - Portland, today and tomorrow
Today (9 August): Air quality in St. Johns is fair. AQI and O3 are fair; PM2.5, PM10, NO2, SO2, CO, HCHO, and PM1 are good. Pollution peaks around 6:00 AM (O3: 37.5/100).
Tomorrow (10 August 2026): Air quality in St. Johns is fair. All pollutants stay as today. Pollution peaks around 8:00 AM (O3: 35.9/100). 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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Portland's St. Johns air quality reflects the North Portland neighbourhood adjacent to the St. Johns Bridge and the Columbia River industrial corridor, with vehicle traffic on N Lombard Street and the surrounding industrial legacy and residential character contributing local sources. The Columbia River provides limited ventilation, while the surrounding industrial corridor's background emissions and the neighbourhood's working-class character maintain moderate to above-average North Portland readings throughout most of the year.
Today - 9 August | Pollution peaks at 06:00
AQI:
Fair
37.5/100
PM2.5 (fine particles):
Good
6.6/100
PM10 (coarse particles):
Good
4.3/100
NO2 (nitrogen dioxide):
Good
5.9/100
O3 (ozone):
Fair
37.5/100
SO2 (sulfur dioxide):
Good
0.4/100
CO (carbon monoxide):
Good
0.0/100
HCHO (formaldehyde):
Good
9.7/100
PM1 (ultrafine particles):
Good
4.6/100
Levels show the poorest local air quality during the day
Tomorrow - 10 August | Pollution peaks at 08:00
AQI:
Fair
35.9/100
PM2.5 (fine particles):
Good
8.6/100
PM10 (coarse particles):
Good
5.4/100
NO2 (nitrogen dioxide):
Good
7.4/100
O3 (ozone):
Fair
35.9/100
SO2 (sulfur dioxide):
Good
0.3/100
CO (carbon monoxide):
Good
0.0/100
HCHO (formaldehyde):
Good
6.8/100
PM1 (ultrafine particles):
Good
6.6/100
Other Landmarks in Portland
Frequently Asked Questions
Is air quality bad in St. Johns right now?
On 9 August 2026, overall air quality in St. Johns is fair. AQI is the main air quality indicator at 37.5/100. Pollution peaks around 6:00 AM (O3: 37.5/100).
Will air quality be worse tomorrow in St. Johns?
On 10 August 2026, air quality conditions in St. Johns will be similar to today, with AQI forecast at fair at 35.9/100. Pollution peaks around 8:00 AM (O3: 35.9/100).
When is air pollution at its worst in St. Johns?
This neighborhood in Portland sees air quality shift through the year: spring is often the freshest stretch, sandwiched between winter rain and summer fire season, but by late summer, wildfire smoke can override the region's usual clean-air advantage for days at a time. Coastal areas see relatively little of the smoke that can settle into inland valleys during fire season.
Are air quality levels in St. Johns 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.
Why doesn’t the forecast always reflect wildfire impacts?
Airmine’s forecast uses CAMS (Copernicus Atmosphere Monitoring Service) as its background atmospheric model. While CAMS includes wildfire emissions, these are derived from satellite observations and are not available in real time. During rapidly evolving wildfire events, there may therefore be a delay before increased emissions are incorporated into the model. As a result, the forecast may temporarily underestimate PM₂.₅ and other pollutants associated with wildfire smoke.
During rapidly evolving wildfire events, CAMS may lag by approximately 1–2 days before increased wildfire emissions are fully represented, which can lead to temporary underestimation of PM₂.₅ concentrations in Airmine’s forecast.
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Data provided by Airmine — Last update: 10 August 2026 at 02:34 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.
Disclaimer: Forecasts are provided for informational purposes only and should not be relied upon as medical advice. Actual pollen and air quality conditions may vary from the forecast. If you have allergies, asthma, or another medical condition, consult a healthcare professional. Please see our Terms of Service for important information about limitations of liability.
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