Air Quality in Chicago
Air quality in Chicago is good right now, at AQI 33, and today's forecast keeps it there — the highest hourly value is AQI 33. Today's main contributor is ozone, at 67 µg/m³.
By pollutant
- O₃ ozone · sets the index nowAQI 33
- PM₂.₅ fine particlesAQI 11
- PM₁₀ coarse particlesAQI 3
- NO₂ nitrogen dioxideAQI 3
- CO carbon monoxideAQI 2
- SO₂ sulfur dioxideAQI 1
Modeled forecast data. AQI values come from atmospheric models (CAMS via Open-Meteo), not local monitoring stations. Readings can differ from ground-level conditions — for exact street-level values, consult an official air quality station near you. The forecast is calculated for a grid square, roughly 11 km across Europe and 45 km elsewhere, and air quality can vary within one square.
The next 48 hours
Hourly air quality index for Chicago · Local time (CDT)
Good ≤ 50
Show hourly data table
| Time | AQI | PM₂.₅µg/m³ | PM₁₀µg/m³ | O₃µg/m³ | NO₂µg/m³ | SO₂µg/m³ | COmg/m³ | °C |
|---|---|---|---|---|---|---|---|---|
| Today | ||||||||
| 00:00 | 31 | 4.1 | 4.4 | 71 | 2.9 | 0.7 | 0.16 | 8° |
| 01:00 | 31 | 2.9 | 3.2 | 73 | 2.4 | 0.7 | 0.16 | 7° |
| 02:00 | 31 | 2.1 | 2.3 | 74 | 2.0 | 0.7 | 0.16 | 6° |
| 03:00 | 32 | 1.6 | 1.7 | 74 | 1.9 | 0.7 | 0.16 | 5° |
| 04:00 | 32 | 1.2 | 1.3 | 73 | 2.4 | 0.7 | 0.16 | 4° |
| 05:00 | 33 | 1.0 | 1.1 | 71 | 4.0 | 0.8 | 0.16 | 4° |
| 06:00 | 33 | 1.1 | 1.2 | 67 | 6.4 | 1.0 | 0.16 | 3° |
| 07:00 | 33 | 1.7 | 1.8 | 64 | 8.4 | 1.2 | 0.17 | 4° |
| 08:00 | 33 | 2.8 | 3.0 | 61 | 9.9 | 1.4 | 0.17 | 4° |
| 09:00 | 32 | 3.6 | 3.8 | 57 | 11 | 1.7 | 0.18 | 6° |
| 10:00 | 31 | 4.0 | 4.3 | 56 | 12 | 2.0 | 0.18 | 8° |
| 11:00 | 30 | 4.5 | 4.7 | 58 | 12 | 2.3 | 0.18 | 9° |
| 12:00 | 29 | 4.9 | 5.2 | 62 | 11 | 2.5 | 0.18 | 10° |
| 13:00 | 29 | 5.0 | 5.3 | 65 | 11 | 2.8 | 0.18 | 11° |
| 14:00 | 28 | 5.4 | 5.7 | 67 | 10 | 3.1 | 0.18 | 12° |
| 15:00 | 28 | 5.7 | 6.0 | 69 | 10 | 3.3 | 0.18 | 12° |
| 16:00 | 29 | 5.8 | 6.1 | 68 | 12 | 3.5 | 0.18 | 12° |
| 17:00 | 29 | 5.7 | 6.0 | 61 | 17 | 3.5 | 0.18 | 11° |
| 18:00 | 29 | 6.6 | 6.9 | 51 | 24 | 3.5 | 0.19 | 9° |
| 19:00 | 29 | 7.3 | 7.5 | 43 | 30 | 3.3 | 0.20 | 8° |
| 20:00 | 28 | 7.1 | 7.3 | 40 | 32 | 3.0 | 0.20 | 7° |
| 21:00 | 27 | 6.8 | 6.9 | 39 | 33 | 2.6 | 0.20 | 7° |
| 22:00 | 25 | 6.4 | 6.6 | 39 | 32 | 2.3 | 0.19 | 6° |
| 23:00 | 24 | 6.2 | 6.3 | 40 | 30 | 2.1 | 0.19 | 6° |
| Tomorrow | ||||||||
| 00:00 | 22 | 6.1 | 6.2 | 42 | 26 | 2.0 | 0.19 | 5° |
| 01:00 | 21 | 6.1 | 6.3 | 43 | 23 | 1.9 | 0.20 | 5° |
| 02:00 | 20 | 6.4 | 6.5 | 42 | 21 | 1.8 | 0.20 | 5° |
| 03:00 | 20 | 6.0 | 6.1 | 41 | 21 | 1.7 | 0.20 | 4° |
| 04:00 | 20 | 5.8 | 5.9 | 39 | 21 | 1.7 | 0.20 | 4° |
| 05:00 | 21 | 5.8 | 5.9 | 36 | 22 | 1.7 | 0.20 | 4° |
| 06:00 | 22 | 5.9 | 6.0 | 34 | 24 | 1.7 | 0.20 | 4° |
| 07:00 | 23 | 6.8 | 6.9 | 33 | 24 | 1.8 | 0.20 | 4° |
| 08:00 | 24 | 7.9 | 8.0 | 36 | 22 | 1.9 | 0.20 | 5° |
| 09:00 | 25 | 8.0 | 8.1 | 41 | 19 | 2.1 | 0.20 | 7° |
| 10:00 | 25 | 7.6 | 7.7 | 47 | 16 | 2.3 | 0.20 | 10° |
| 11:00 | 26 | 6.4 | 6.5 | 54 | 13 | 2.5 | 0.20 | 12° |
| 12:00 | 26 | 5.9 | 6.0 | 61 | 10 | 2.7 | 0.19 | 13° |
| 13:00 | 27 | 5.6 | 5.8 | 67 | 8.1 | 2.9 | 0.18 | 14° |
| 14:00 | 27 | 5.5 | 5.6 | 72 | 6.9 | 2.9 | 0.17 | 15° |
| 15:00 | 27 | 5.4 | 5.5 | 77 | 6.6 | 2.9 | 0.17 | 16° |
| 16:00 | 27 | 5.2 | 5.4 | 77 | 8.4 | 2.8 | 0.17 | 17° |
| 17:00 | 29 | 5.9 | 6.1 | 71 | 14 | 2.8 | 0.17 | 16° |
| 18:00 | 30 | 6.6 | 6.9 | 60 | 21 | 2.7 | 0.18 | 13° |
| 19:00 | 31 | 7.4 | 7.7 | 51 | 27 | 2.7 | 0.19 | 11° |
| 20:00 | 31 | 7.9 | 8.3 | 44 | 32 | 2.8 | 0.20 | 9° |
| 21:00 | 30 | 7.9 | 8.5 | 38 | 35 | 2.9 | 0.20 | 8° |
| 22:00 | 28 | 7.9 | 8.5 | 35 | 36 | 2.9 | 0.20 | 8° |
| 23:00 | 27 | 7.7 | 8.3 | 36 | 33 | 2.8 | 0.20 | 9° |
Today at a glance
The week, hour by hour
Tomorrow looks just as good, peaking at AQI 31 (good). Over the 5-day forecast the daily peaks run Saturday (good), Sunday (good), Monday (moderate), Tuesday (moderate), and Wednesday (moderate), with Tuesday the worst of the stretch.
Each cell is one forecast hour, coloured by air quality band. A ring marks the day's worst hour. The blue ring marks the current hour.
12° / 3°
17° / 4°
20° / 10°18° / 13°21° / 12°Pollutants right now
Every pollutant on the same AQI scale as the big number above. The index only ever equals the worst score — pollutants don't add up.
The colors cover a wide area, not a street. The forecast works in squares of roughly 11 km across Europe and 45 km elsewhere, so the air where you actually are can differ from the shade under the city.
Check air quality in: Milwaukee · Grand Rapids · Aurora · Madison · Joliet
About Chicago
Air quality in Chicago — common questions
What is the air quality in Chicago right now?
When is air quality expected to be worst in Chicago today?
What will the air quality be in Chicago tomorrow?
Which pollutants drive the AQI in Chicago today?
| Pollutant | Sub-index | Level | WHO 2021 | Vs guideline |
|---|---|---|---|---|
| O₃ | 33 | 67 µg/m³ | 100 µg/m³ (8h) | 0.7× |
| PM₂.₅ | 11 | 1.1 µg/m³ | 15 µg/m³ (24h) | 0.1× |
| PM₁₀ | 3 | 1.2 µg/m³ | 45 µg/m³ (24h) | 0.03× |
| NO₂ | 3 | 6.4 µg/m³ | 25 µg/m³ (24h) | 0.3× |
| CO | 2 | 0.16 mg/m³ | 4 mg/m³ (24h) | 0.04× |
| SO₂ | 1 | 1.0 µg/m³ | 40 µg/m³ (24h) | 0.03× |
Is air quality improving in Chicago this week?
How is air quality forecast for Chicago, Illinois, United States?
About the Air Quality Index
What is the Air Quality Index (AQI)?
The Air Quality Index (AQI) is a tool developed by the U.S. Environmental Protection Agency (EPA) to communicate how clean or polluted the air is and what health effects may be of concern. The AQI runs from 0 to 500 and is divided into six color-coded categories: Good, Moderate, Unhealthy for Sensitive Groups, Unhealthy, Very Unhealthy, and Hazardous.
How do I read the AQI values?
Lower AQI values mean cleaner air. An AQI of 0–50 (green) is Good, 51–100 (yellow) is Moderate, 101–150 (orange) is Unhealthy for Sensitive Groups, 151–200 (red) is Unhealthy, 201–300 (purple) is Very Unhealthy, and 301–500 (maroon) is Hazardous. When the AQI exceeds 100, air quality is considered unhealthy — at first for sensitive groups, then for everyone as the AQI rises.
Who are the sensitive groups?
Sensitive groups include people with heart or lung disease, older adults, children and teenagers, people who are pregnant, and people who are active outdoors. These groups are more likely to be affected when air quality is poor. If you are in a sensitive group, you can reduce your exposure by taking fewer and shorter outdoor walks when the AQI is elevated.
Which pollutants are measured?
The AQI covers five major pollutants regulated under the Clean Air Act: ground-level ozone (O₃), particle pollution (PM₂.₅ and PM₁₀), carbon monoxide (CO), sulfur dioxide (SO₂), and nitrogen dioxide (NO₂). An AQI value is calculated for each pollutant, and the highest value determines the overall AQI.
Where does the air quality data come from?
The hourly air quality data comes from the Copernicus Atmosphere Monitoring Service (CAMS), which provides global atmospheric composition forecasts. The data is accessed via Open-Meteo, which provides free, open-source weather and air quality APIs. The AQI categories and health guidance follow the EPA AirNow technical standard (EPA-454/B-24-002).
What are the health effects of poor air quality?
Poor air quality can cause respiratory issues, aggravate asthma and allergies, and increase the risk of cardiovascular problems. Fine particles (PM₂.₅) can penetrate deep into the lungs and bloodstream. The World Health Organization estimates that air pollution causes millions of premature deaths worldwide each year.
How often is the air quality forecast updated?
The CAMS air quality forecast is updated regularly using atmospheric models. Weather data such as temperature and cloud cover comes from Open-Meteo. The forecast provides up to 5 days of hourly air quality predictions.
AQI Levels (US EPA Standard)
AQI categories and health guidance: EPA AirNow (EPA-454/B-24-002, May 2024). Air quality data: CAMS/Copernicus via Open-Meteo.
