Worst air pollution Willis Tower (Skydeck) - Chicago, today and tomorrow
Today (20 September): Air quality in Willis Tower (Skydeck) is fair. AQI, PM2.5, and NO2 are fair; PM10, O3, SO2, CO, HCHO, and PM1 are good. Pollution peaks around 4:00 PM (NO2: 34.6/100).
Tomorrow (21 September 2026): Air quality in Willis Tower (Skydeck) is fair. O3 increases to fair; all other pollutants stay as today. Pollution peaks around 4:00 PM (NO2: 23.8/100). 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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Chicago's Willis Tower Skydeck air quality reflects the Loop's dense commercial canyon position, with vehicle traffic on Wacker Drive and the surrounding extraordinary concentration of urban vehicle emissions generating sustained NO₂. The enclosed Loop canyon geometry concentrates emissions at street level, while the Skydeck's extraordinary 412-metre elevation places visitors well above the urban boundary layer in generally excellent upper-atmosphere conditions throughout most of the year.
Today - 20 September | Pollution peaks at 16:00
AQI:
Fair
34.6/100
PM2.5 (fine particles):
Fair
20.3/100
PM10 (coarse particles):
Good
9.7/100
NO2 (nitrogen dioxide):
Fair
34.6/100
O3 (ozone):
Good
19.3/100
SO2 (sulfur dioxide):
Good
0.8/100
CO (carbon monoxide):
Good
0.6/100
HCHO (formaldehyde):
Good
3.5/100
PM1 (ultrafine particles):
Good
3.4/100
Levels show the poorest local air quality during the day
Tomorrow - 21 September | Pollution peaks at 16:00
AQI:
Fair
23.8/100
PM2.5 (fine particles):
Fair
20.8/100
PM10 (coarse particles):
Good
9.9/100
NO2 (nitrogen dioxide):
Fair
23.8/100
O3 (ozone):
Fair
20.0/100
SO2 (sulfur dioxide):
Good
0.9/100
CO (carbon monoxide):
Good
0.6/100
HCHO (formaldehyde):
Good
6.6/100
PM1 (ultrafine particles):
Good
3.4/100
Other Landmarks in Chicago
Sports venues in Chicago
Frequently Asked Questions
Is air quality bad in Willis Tower (Skydeck) right now?
On 20 September 2026, overall air quality in Willis Tower (Skydeck) is fair. AQI is the main air quality indicator at 34.6/100. Pollution peaks around 4:00 PM (NO2: 34.6/100).
Will air quality be worse tomorrow in Willis Tower (Skydeck)?
On 21 September 2026, air quality conditions in Willis Tower (Skydeck) will be similar to today, with AQI forecast at fair at 23.8/100. Pollution peaks around 4:00 PM (NO2: 23.8/100).
When is air pollution at its worst in Willis Tower (Skydeck)?
Air quality around Willis Tower (Skydeck) changes with the seasons. Typically, the mildest, cleanest weather usually falls in spring and autumn, while prolonged summer heat waves are when air quality most often dips into unhealthy territory. Calm, cold winter spells can occasionally allow local pollution to build up before the next weather system clears it.
Are air quality levels in Willis Tower (Skydeck) 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: 20 September 2026 at 20:27 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.
Some text on this page may be generated or summarised using artificial intelligence (AI). Wherever possible, AI-generated content is enriched with Airmine's proprietary data to improve its accuracy and relevance. However, AI-generated content may still contain errors, omissions, or inaccuracies.
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